Adding Amines to Steam for Humidification

FEATURE Adding amines to steam for humidification

Humidity control is required in all health care facilities. Direct injection of steam from a central boiler plant is the most economical humidification system. The steam carries neutralizing amines—corrosion-inhibiting chemicals—that are added to boiler feedwater to prevent pipe corrosion. When the steam condenses, the amines neutralize the resulting carbonic acid and raise the pH of the condensate, which helps reduce, slow down, or prevent corrosion to the condensate system. This technical review compares the use of ‘clean steam’ to ‘utility’ steam and discusses the health effects, regulation, and control of three of the most commonly used amines in ‘utility’ steam: morpholine, cyclohexylamine (CHA), and diethylaminoethanol (DEAE) to make the point that proper application, control, monitoring and oversight of amines in a ‘utility’ steam system of a health care facility is safe, feasible and economical.

By Farhad Memarzadeh The use of direct steam-injection or inappropriate for the facility, or humidification has advantages and dis- some other technical or human error advantages. Briefly, some of the advan- occurred to cause elevated levels of the INTRODUCTION tages include a relatively low purchase chemical in the surroundings. Further- and installation cost; the ability to pro- more, the measured levels of the che- In this technical review, we examine duce excellent vapor/steam quality i.e., micals, despite the fact that they were the use of ‘utility’ steam containing the impurities in the steam have been reported to have caused symptoms neutralizing amine additives under removed; a large amount of steam can including respiratory irritation, nau- controlled conditions in support of be introduced from a relatively small sea, vomiting, or contact dermatitis, the use of ‘utility’ steam in healthcare system; the system is responsive to were all below the allowable levels as facilities. Humidity control is required control because a direct steam humi- regulated by the Food and Drug in all health care facilities and many difier has a variety of control valves Administration (FDA), Occupational other facilities where people spend sized for the system; it typically has Safety & Health Administration large segments of their day. reliable performance and a long life- (OSHA), National Institute for Occu- Direct injection of steam from a cen- span; and a direct-injection steam pational Safety and Health (NIOSH), tral boiler plant is the most economical humidifier is perhaps the most reliable the American Conference of Govern- humidification system for many com- and low maintenance type of commer- mental Industrial Hygienists (ACGIH) mercial and industrial facilities. Direct cial humidifier.2 The high tempera- and other regulatory entities. steam-injection systems are subject to tures of the steam used in direct corrosion. The U.S. Federal Highway steam-injection kills fungal and bacter- Administration (FHWA) released a ial organisms that can otherwise cause TYPES OF HUMIDIFIER SYSTEMS study in 2002 on the direct costs asso- occupant illness or discomfort and is ciated with metallic corrosion in 26 U.S. thus the system of choice in many Although direct injection of steam industry sectors. The study determined facilities. from a central boiler plant is com- that the annual cost of corrosion in the The disadvantages, though off-put- monly used for the humidification sys- United States at that time was estimated ting to some users, are very manage- tem in many commercial and to be greater than $300 billion. In able. They primarily revolve around industrial facilities, there are alternate the pharmaceutical industry, the total the toxicity of the corrosion prevention means of humidification. Among the annual direct cost of corrosion was esti- chemicals injected into a closed loop alternatives are steam-to-steam heat mated at $1.7 billion per year (8 percent system. These chemicals typically have exchangers and stand-alone humidi- of total capital expenditures). Although an offensive odor that is detectable fiers. Design engineers should clarify the costs of corrosion related to the well below the regulated exposure lim- the quality of the steam and confirm if health care industry or specifically to its. The evidence suggests that in the there is any direct impact to the pro- direct injection of steam used in humi- reported case studies where people duct or risks to the users and others dification systems were not listed, the were affected by the presence of the who might be exposed directly or indir- study provided data to support the need chemicals in the indoor air or depos- ectly to the steam, before undertaking for a combination of safe, effective and ited on surfaces, the chemical injection the design. This clarification will mini- less expensive corrosion prevention or dilution process was faulty, the mize the risk of product contamination measures and improved application steam delivery system was defective, or potentially hazardous human expo- 1 and monitoring systems. the indoor ventilation was inadequate sures and may also save money by

1871-5532/$36.00 Division of Chemical Health and Safety of the American Chemical Society 5 http://dx.doi.org/10.1016/j.jchas.2014.01.002 Published by Elsevier Inc. using a lower-cost type of steam. The Steam-to-steam converters maintenance costs, sensitive humidity design engineer must take into account Perhaps the best option for those who control, and cleanliness are high prio the potential level of impurities, already have a steam boiler providing rities. The technology has a cost and including boiler additives (amines humidification is the steam-to-steam large energy saving advantage over and hydrazines) and other impurities converter. The chemical-laden steam other humidification technologies that may be present in the steam sys provided by the boiler is put through a when simultaneous cooling and humi tem that could find their way into the tube-type heat exchanger that is dification is required. Ultrasonic humi final end product when humidifying a immersed in a tank of city water. The difiers were judged to have notable process airstream. The design engineer boiler steam heats the city water potential and to be life-cycle cost- should look specifically for areas through the exchanger and returns it effective in the proper applications. where open processing takes place, to the boiler. The city water, which has and where the steam could possibly not come in contact with chemical Direct-injection type humidifiers contribute significantly to the contam additives, becomes the source of steam Direct-injection humidifiers offer the ination of the end product. In these for humidification. In this way, steam lowest initial and operating costs, cases, a purer grade of steam (clean is used, and there is no increase in and the most efficient and best level steam) should be selected and applied. energy consumption as with electric of controls with precise control of out units. The chemical additives amines put. These types of humidifiers may be Self-contained electric humidifiers never reach the air stream. used to disperse the steam from the Potable water is used to generate steam central boiler plant. In a ‘‘clean’’ steam without any chemical additives. At Ultrasonic humidifiers system with direct injection type humi least two major designs are available. Ultrasonic humidifiers are more effi difiers, clean steam is generated in a City water is sent to a sealed plastic cient and require less maintenance dedicated gas-fired boiler, steam-to tank and heated with an electrode-type than competing humidifier technolo steam converter, or electric steam gen heating element. Electric current pas gies such as indirect steam-to-steam. erator. The disadvantages of the clean- sing through the water, causing it to The greatest energy and cost savings steam system include the need for boil, generates steam. The steam is from ultrasonic humidifiers occur in stainless steel steam and condensate delivered to the duct through a variety applications requiring simultaneous system components, and the make of dispersion systems. The disadvan cooling and humidifying. The types up water must be treated in the reverse tage of this design is that dissolved of facilities where this technology is osmosis or de-ionization equipment. minerals in the city water build up in best used are computer rooms for data the tank, reducing output and even processing centers, communication tually requiring replacement. No type centers with large amounts of electro ‘CLEAN STEAM’ VS. ‘UTILITY’ STEAM of pretreatment can be used; deionized nic switching equipment, clean rooms or demineralized water is not conduc for electronic and pharmaceutical Steam is available and produced in tive enough for the heating element to manufacturing, and hospital operating different grades depending on its appli work, and softened water is often too rooms. They do not require anti-corro cation. ‘Clean’ steam is used in the conductive, which may lead to arcing sive additives that affect the IAQ of pharmaceutical and health care indus inside the unit. If a stainless steel eva buildings using direct-steam humidi tries where moist-heat sterilization is porating chamber with a submerged fiers. There are two potential disadvan critical and in processes where the heating element is used instead, city tages of ultrasonic humidifiers. They steam may come in contact with inges water can still be used but it can be must use mineral-free, deionized water tible or parenteral products or their pretreated to soften, demineralize, or or water treated with reverse osmosis. packaging. According to the California deionize the water. With these higher Treated water reduces maintenance Mechanical Code3, humidification is quality waters, the units last much costs because it eliminates calcium required in operating rooms, cysto longer. All electric units require large deposits, but increases other operating scopy, cardiac catheter labs, delivery amounts of power and add consider costs. Also, the cool mist from ultra rooms, recovery rooms, newborn nur ably to a facility’s electric bill, a factor sonic humidifiers absorbs energy from sery, intensive care newborn nursery, that should be considered when an the supply air as it evaporates and and in intensive care rooms. ‘Clean’ adequately sized boiler is already avail provides a secondary cooling effect. steam is also used in humidification able. Electric humidification system This cooling is beneficial in applica of clean rooms in pharmaceutical must be on emergency power so addi tions where simultaneous humidifica manufacturing plants in the manufac tional costs of emergency power gen tion and air conditioning are required, ture of sterile compounds for injection erators and related switchgear present but detrimental when heating and or wound application and for ingesti a disadvantage. As a result, electric- humidifying. Ultrasonic humidifiers ble medications. In these environ type humidifiers are used mostly in are also well suited to applications ments, entrained contaminates may the existing facilities where only a requiring tight controls on humidity affect downstream products and pro few units are needed and where the 1%) due to their instantaneous cesses exposed to the humidification emergency power system has sufficient response. Ultrasonic humidifiers have system such as open aseptic proces capacity. the highest benefit when energy, sing. Some forms of ‘clean’ steam

6 Journal of Chemical Health & Safety, July/August 2014 may be used in the food production Purified water must meet specific cri Typically, humidification is achieved industry. Historically, these industries teria for conductivity, total organic in two stages: primary and secondary. have used filtered steam for steriliza carbon and microbial colony forming The primary humidifier, installed in tion. However, in demanding ever- unit (CFU) limits. Conductivity, the the air-handling unit, adds moisture higher levels of purity assurance these tendency of water that contains ions to maintain relative humidity in non sectors have migrated to the adoption to conduct electricity, is used to mea critical patient areas of the facility at of ‘clean’ steam. ‘Clean’ steam is now sure feed water and lower qualities of approximately 35 percent relative used as standard in a range of quality- treated water. The more ions present in humidity. The secondary humidifiers critical processes at risk from plant the water, the higher the conductivity. are located downstream of the final steam contaminants. It is measured as the Siemen(S), micro filters and downstream of the terminal To create ‘clean’ steam, a secondary siemens/centimeter (mS/cm) or micro unit with the reheat coil serving each generator with controlled feed water is mho/cm.6 Total Organic Carbon space where individual temperature used. The design of the steam distribu (TOC) is a the concentration of all and humidity controls are required. tion network, material selection, and organic carbon atoms covalently This steam is referred to as ‘utility’’ installation practices are all critical for bonded in the organic molecules of a steam. Typically, the water supplying minimizing steam degradation thus given sample of water. TOC is typically the boiler is pre-treated to remove or ensuring acceptable purity and quality measured in parts per million (ppm or adjust contaminants such as salts and at the point of use. By using ‘clean’ mg/L). Microbial colony forming units dissolved gasses, but pre-treatment steam, manufacturers know there will (CFU) are a measure of microbial con doesn’t necessarily remove all con be no boiler additives, volatiles, and tent in water samples that are plated on taminants and may not be economic particulates that could taint, blight, a growth media, incubated and ally feasible. or contaminate final products. In addi counted microscopically. Although ‘Utility’ steam from a conventional tion, ‘clean’ steam is often used not most microbial species are destroyed boiler contains anti-corrosion chemi only to remove contaminants, but also under the intense heat and pressure of cals that help prevent equipment fail to ensure the quality control of critical a steam process, the endotoxin by-pro ure, lower maintenance costs, and attributes such as dryness, superheat, ducts they produce are stabile under improve maintainability, efficiency, and production of non-condensable these same conditions and are the con reliability, treatment, system life and gases, all of which could adversely taminating factor of concern in the safety of the boiler and cooling sys affect the process and equipment. pharmaceutical industry. tems. A steam/condensate system is It is costly to use ‘clean’ steam. The Water for injection (WFI) has more subject to corrosion due to the carbon cost is increased primarily by two fac stringent CFU limits, as well as endo dioxide (CO2) present in the steam. tors: (1) it is expensive to purify water toxin limits and production specifica Carbon dioxide is produced when car to the necessary specifications prior to tions than PW. Water for injection is bonate and bicarbonate alkalinities in its being introduced into the boiler produced by reverse osmosis and dis boiler feed water thermally decompose system and (2) the non-corrosive con tillation to remove organics, bacteria in the boiler. Carbon dioxide is driven duit components that should be used and pyrogens.7 off as a gas and is carried with the in a ‘clean’ steam system are of very Pharmaceutical quality ‘clean’ steam steam. It then dissolves in the conden high quality and expensive to purchase does not contain corrosion inhibiting sate to form carbonic acid, which and maintain. additives and because of it’s low con causes corrosion in condensate piping, Although the use of ‘clean’ steam is ductivity water or condensate, it is receivers, and traps, commonly com determined by Good Manufacturing corrosive to materials commonly used posed of carbon steel, gunmetal, and 8 Practice (GMP) as detailed in the Code in ‘utility’ steam systems. The metal bronze. Some of the CO2 dissolves in of Federal Regulations (CFR 21, Part components for ‘clean’ steam systems the condensate and reacts with water 211),4 specific recommendations for must be of extremely high quality and to form carbonic acid having a pH of steam composition or its condensate are usually AISI 316L stainless steel, about 4.5–5.5, which can severely are lacking. The water used to produce titanium9 or nonmetallic materials damage the entire condensate system the steam in the pharmaceutical indus such as ethylene propylene diene and corrosion by-products are carried try, so as to generate a ‘clean’ product monomer (EPDM) rubber10 and poly back to cause fouling and deposition in at the point of use, is regulated by the tetrafluoroethylene (PTFE).11 the feed water tank and boiler. The US Pharmacopoeia (USP).5 The USP Even in a ‘clean’ steam system a form presence of oxygen from make-up does not define criteria for ‘clean’ of corrosion called ‘rouging’ can occur. water and leakage into the system steam. Steam purity is determined by When ‘rouging’ occurs, the system can cause the formation of iron oxide individual pharmaceutical manufac must be shut down to perform a che to varying degrees that result in pitting. turers so as to meet the GMP require mical cleaning process to remove pos In the presence of acidity caused by ment to avoid product contamination. sible contaminants to the final CO2, corrosion products are dissolved The USP defines Purified Water product.12 causing further damage to the system. (PW) and Water for Injection (WFI) The most economical humidifica Corrosion may manifest as a thinning – the two grades of water primarily tion system is direct injection of the or grooving of the condensate pipe or used for pharmaceutical manufacture. steam from the central boiler plant. degradation of pipe threads.

Journal of Chemical Health & Safety, July/August 2014 7 Neutralizing amines, volatile alka CHARACTERISTICS OF the cost, consumption rate, length of line compounds that are carried with NEUTRALIZING AMINES the condensate lines, amount of car the steam, are added to boiler feed bon dioxide generated in the boiler and water to prevent such corrosion. When In order to maintain a safe indoor air thermal stability must be considered as the steam condenses, the amines neu quality (IAQ), design engineers and well. Because of the complexity of tralize the resulting carbonic acid, rais owners should be knowledgeable combined amine additive interactions ing the pH of the condensate and about the chemical additive properties and the systems for which they are preventing corrosion to the conden with respect to their purpose, use and selected, sophisticated computerized sate system. Neutralizing amines are toxicity as each has different proper modeling techniques may be used to fed into a boiler system to maintain a ties, toxicities, advantages and disad predict the amine distribution and pH moderately alkaline pH range from 8.2 vantages. profile across the system. to 9.2. The amines found in steam used Neutralizing amines are organic The most commonly used neutraliz for humidification are carried via compounds that behave as weak bases ing amines in boiler systems are, humidifiers into room air, where they and have a strong, characteristic, fishy cyclohexylamine (CHA), diethylami are inhaled and/or inadvertently or ammonia-like odor. They are clas noethanol (DEAE), morpholine, ingested via hand to mouth contact sified by their (1) neutralizing capacity ammonia methoxypropylamine of surface deposits. These amines, have – a measure of how much amine it (MPA), monoethanolamine (ETA) been implicated, mostly based on takes to neutralize a given amount of because, used individually or in com anecdotal evidence, as the causative acid, expressed as the parts per million bination, they are capable of prevent agents for adverse health effects such (ppm) of carbonic acid neutralized per ing corrosion in systems of various as eye, upper respiratory, and skin irri ppm of neutralizing amine; (2) alkali lengths, and it is fairly easy to control tations in humans and animals. The nity or pH and (3) vapor/liquid distri their indoor air concentrations well chemicals are carried via humidifiers bution ratio (V/L) defined as the below accepted exposure limits into room air, where they are inhaled tendency of the chemical compound through the use of standard operating and/or ingested. When amine-treated to condense with the steam conden procedures and practices. Of these, steam is used for direct humidification sate. For neutralizing amines, the V/L CHA, DEAE and morpholine are the of human occupied space, some represents the amines interaction most commonly used neutralizing amount of the volatile amines may be between the liquid and steam phases amines in steam boiler humidification present in the humidified air supply. and the pressure, temperature and pH systems in health care facilities. This is The adverse health events attributed of the steam/condensate environment. primarily because they have been to neutralizing amine exposure from The higher the ratio the more likely the approved by the FDA for use in food additives in ‘utility’ steam systems have amine will stay with the steam in a processing applications or in other oftenbeeninadequatelyresearched and distribution system, while an amine words, for ingestion. The USDA per interpreted, leading to the false assump with a lower ratio will condense earlier mits the use of the amines in meat and tion that it is necessary to use ‘clean’ depending on its chemical properties poultry plants. As described in the sec steam in the health care environment. and the variables of pressure, tempera tion ‘Regulation of Neutralizing The California Code Application Notice ture and pH. A higher ratio product Amines’,FDA,OSHA,andACGIH (CAN) #4-408.1.513 in part, reads: ‘‘If therefore is a better choice for a larger/ exposure limits are significantly higher steam from a central boiler plant will be longer system while a lower ratio pro than any levels that have been found in injected directly into air stream, it is duct is best for a smaller system. the classic exposure case studies recommended, but not required that The neutralizing amines are corro reported in the literature. Since no the design professional verify that the sive in and of themselves before they Federal government regulations exist boiler water will not be treated with chemically react with an acid to neu governing the use of amines in direct chemicals or contain minerals which tralize that acid and they must be steam humidification systems (other are known to be hazardous to health handled judiciously. Although there than in the food industry in which all or which might contribute to an indoor are alternatives to using neutralizing the existing standards and guidelines air quality problem.’’13 amines in certain situations, the use are based on ingestion) the water treat The Environmental Protection of neutralizing amines remains the ment industry tends to follow FDA Agency (EPA) has issued warnings method of choice in many facilities limits for amine levels in steam used regarding boiler chemicals: ‘‘Heating because of its reasonable cost and gen for direct steam humidification sys system steam should not be used in eral ease of use and monitoring.16–19 tems. However, lacking better or more the HVAC humidification system, as Neutralizing amines each have dif current scientifically based criteria, it may contain potentially harmful che ferent chemical properties so that a this is all the guidance currently avail micals such as corrosion inhibitors.’’14 combination of appropriate amines able to manufacturers and regulators. ‘‘Steam humidifiers should utilize may be necessary to address the corro clean steam rather than steam created sion effects on different segments of Cyclohexylamine from chemically treated boiler water, the system. In addition to selecting a Cyclohexylamine (CHA), a colorless so occupants will not be exposed to neutralizing amine or combination of to yellow liquid with a strong fishy chemicals.’’15 amines based on these characteristics odor, is used primarily for boiler water

8 Journal of Chemical Health & Safety, July/August 2014 treatment in low pressure systems (50 found in nature. Ammonia is sometimes mucosal irritants at high exposure down to 5 psi) and also for systems used in steam lines where the steam levels. Ingestion of CHA and DEAE with long condensate systems where contains a large amount of carbon diox may result in abdominal pain and diar it is used in combination with other ide or where there is significant steam rhea. Dermal contact with DEAE neutralizing amines. It has a high loss from the condensate system. may lead to redness, pain, burns, and vapor–liquid distribution ratio of Although ammonia is relatively inex blisters.22 4.7:1 (i.e., cyclohexylamine will place pensive, it cannot be used in systems The evidence of adverse events 4.7 times the material in the vapor containing copper, nickel or zinc. caused by exposure to neutralizing phase as in the water phase). CHA is Ammonia is also more difficult to adjust amines in the indoor environment is unique among the neutralizing amines correctly between pH 5.5 and 6.5 but it mostly anecdotal with an occasional approved for steam boiler systems in can neutralize carbon dioxide to pH scientific study that provides evidence that it will stay with the steam as pres 8.5–9.0 when the steam condenses. to support the accepted regulatory lim sure is reduced. Cyclohexylamine is a However, it is very volatile and neutra its for exposure rather than human mutagen and a corrosive chemical that lizes only at the end of the condensation exposure to concentrations well below can be an acute and chronic irritant to rather than as required during the these limits. Well-designed scientific the lungs, skin, and eyes. Inhalation whole condensation. studies related to the neutralizing exposure can cause dizziness, light Other neutralizing amines some amines are scarce. The classic work headedness, anxiety, nausea and times used for corrosion inhibition place examples used as evidence of vomiting. It is also a flammable liquid include: methoxypropylamine exposure and adverse effects to neu and a fire hazard. (MOPA) used primarily in the oil tralizing amines reflect inadequate industry in anticorrosion of petroleum ventilation, inadequate research and Morpholine lines; dimethylpropylamine (DMPA) improper ventilation. Morpholine is the amine of choice for used mainly in the foundry industry, The effects of amine exposure have direct sterilization systems and short as a tertiary amine catalyst for the been found to depend on the exposure run systems. It must be blended with production of sand cores (cold box concentration. The greatest (dose- either DEAE or CHA for use in longer process); monoethanolamine (MEA), dependent and statistically significant) systems since it drops out of the steam similar to morpholine, is used for cor increase in mean systolic and diastolic early. It has a low boiling point and low rosion control in steam cycles of power blood pressure was observed 1 h after distribution ration (0.4 parts morpho plants, including nuclear power plants administering cyclohexylamine in sin line in the steam; 1.0 part morpholine with pressurized water reactors. It is gle doses of 5 or 10 mg/kg body weight in the condensate). There are no data sometimes selected because it does not to healthy male volunteers. A slight available on levels of morpholine in accumulate in steam generators (boi drop in heart rate accompanied the ambient and residential indoor air lers) and crevices due to its volatility, vasopressin effect. The plasma cyclo and in drinking water. but rather distributes relatively uni hexylamine levels correlated to the formly throughout the entire steam increase in mean arterial blood pres Diethylaminoethanol (DEAE) cycle. sure. The authors estimated that a Diethylaminoethanol (DEAE), a color cyclohexylamine level of 0.7–0.8 mg/ less liquid with a nauseating, ammonia- ml plasma was still able to produce a 23 like odor, has a vapor–liquid distribu EVIDENCE OF HEALTH RISKS significant hypertensive effect. tion ratio of 1.7, which is between cyclo ASSOCIATED WITH EXPOSURE TO The human olfactory threshold for CORROSION-INHIBITING AMINES hexylamine and morpholine. It is a diethylamine is 0.14 ppm. In a study on good choice in a medium length system perceived acute sensory effects, Acute exposure 24 where either morpholine or cyclohex Lundqvist et al. determined that ylamine used separately would not pro High concentrations of neutralizing there was an increase of nose and vide complete protection. DEAE is not amines in ambient air are suspected eye irritation, and odor perception, effective in low pressure systems to have adverse health effects on with gradually increasing DEAE con because of its high boiling point. DEAE humans and animals. Brief exposure centrations of 12 ppm over 60 min can be compared to morpholine as a has caused nausea, dilated pupils, [time-weighted average concentration primary irritant.20 slurred speech, anxiety, vomiting, and of 10 ppm]. In order to minimize such narcosis. Occupational exposure to irritation symptoms, a 15-min short CHA has been reported to cause head term exposure limit (STEL) of OTHER NEUTRALIZING AMINES ache, nausea, dizziness, vomiting, and 10 ppm is recommended. The Eur rapid and irregular heartbeat. Acute opean Commission, in its recommen Ammonium hydroxide exposure of animals resulted in dation on occupational exposure limits Ammonium hydroxide is a colorless extreme mucous membrane irritation, for diethylamine note that the outcome liquid with a pungent suffocating odor gasping, tremors, clonic muscular of the Lundqvist study suggests that and an acrid taste. Unlike the previously spasms, lung hemorrhage, opaque cor some symptoms of eye and nose irrita mentioned volatile amines, which are neas, vascular lesions, and hemolysis.21 tion might start to occur with DEAE manufactured, the ammonium ion is DEAE and CHA are both acute exposures of about 10 ppm.25

Journal of Chemical Health & Safety, July/August 2014 9 There are no known methods of pre-existing medical condition, and/or DEAE and CHA concentrations are directly measuring concentration of a hypersensitivity (allergy). There are a 2.4 and 0.8 ppb, respectively. During amines in the air; hence, measurement variety of factors that are not the final hour when the humidifier was is derived from the concentration of accounted for in these criteria includ- shut off, the concentrations of both amines in the condensate and related ing that several substances may act in compounds decay to 50% of their amount of supply air. Possibly as a combination with other workplace steady-state values at 61% RH. Of 14 result of this, many of the available exposures, and may be absorbed by samples, DEAE was detected in only case studies, particularly the earliest direct contact that may increase the two, at concentrations of 8 and 10 ppb reported cases, lack good data. Adding overall exposure. with a detection limit of 8 ppb. The to the difficulty in associating expo- In March 1981, NIOSH investiga- amine concentrations measured in this sures to symptoms is the shortage of tors determined that dermatitis and study are significantly lower, by about reported and recorded information for other employee reported symptoms a factor of 10, than those reported in many incidents such as the three occu- in the office area of a pharmaceutical the NIOSH study. The author postu- pational exposures to CHA reported production building were the result of lates that the museum in the NIOSH 26 by Watrous and Schulz in 1950. exposure to a condensation or reaction study had a very limited supply of fresh One brief exposure of about 1 h product of DEAE that had been added air and relied primarily on recirculated involved a worker who noticed a to the air-handling system. The specific air. This study suggests that the con- strong fishy smell. He reported symp- agent could not be identified despite centrations of these amines in indoor toms of nausea, light-headedness and environmental air and surface sam- steam-humidified air remain low anxiety as well as loss of appetite, pling. However, results of sampling enough that they do not present any throat irritation and rapid heartbeat. suggested the presence of a conjugated hazard to health. The primary fate of Air samples were not taken immedi- amine that possesses acidic properties. the amines that are input into the room ately nor were details such as location Environmental and medical evalua- air from steam humidification is prob- of the incident or other worker expo- tions indicated the source of the ably removal to surfaces. sures noted. Air samples taken at an reported symptoms to be the air-hand- In 1988, NIOSH investigated Cin- 27 unspecified time showed 4–10 parts ling system. cinnati Electronics Corporation after per million (ppm) of CHA. Another Similarly, in 1982, there was an 64% of the employees reported an exposure was the result of a worker investigation at a Cornell University ammonia like odor and filed com- splattered with an unknown concen- museum in Ithaca, New York. Forty plaints of rashes, headaches and eye, tration of liquid CHA dissolved in an employees reported eye irritation and nose, and throat irritations while unidentified caustic solution. The indi- dermatitis. DEAE had been added to a working where amine-treated steam 30,17 vidual developed a rash described as humidification system. Air sampling was used in direct humidification. coagulative necrosis on the face and detected minimal DEAE concentra- Investigators determined that four experienced nausea and vomiting 1– tions in only two of 14 samples col- times the recommended amount of 3 h after the exposure. Other symp- lected. The detected DEAE combined CHA and DEAE had been toms included slurred speech and concentrations were three orders of added to the humidification system. widely dilated pupils. The individual magnitude less than the OSHA permis- Air samples were not taken until four appeared to recover completely within sible exposure limits (PEL) of 10 ppm. days after the incident was reported. 24 h of exposure. The third exposure in It was concluded that dermal contact During the time between the outbreak the Watrous and Schulz26 report was with released DEAE that had subse- and sampling, the boilers had been of a supervisor in a CHA plant who quently condensed on surfaces was the flushed with an estimated 25,000– was exposed to CHA vapors and exposure pathway rather than inhala- 75,000 l of makeup water containing experienced classic nausea and vomit- tion because symptoms did not begin normal amounts of corrosion inhibi- ing symptoms. Again, there were no to develop until about two years after tors. Inability to recover CHA or details reported for the incident. the introduction of DEAE into the DEAE suggests that the levels fell The National Institute for Occupa- museum humidification system. below the NIOSH method’s detection tional Safety and Health (NIOSH) has NIOSH recommended that DEAE be limit; however, an accurate measure of 28 investigated several cases related to wiped from surfaces. the amine concentration at the time of 30,17 exposure to boiler steam containing A confirming follow up study con- the incident was never obtained. corrosion-inhibiting chemicals. ducted by Battelle, Columbus, Ohio In 1988, NIOSH also investigated a NIOSH uses environmental evalua- and reported by Edgerton et al.,29 took complaint involving hospital staff at a tion criteria that are intended to sug- consecutive measurement of amines in neonatal intensive care unit and nur- gest levels of exposure to which most an indoor office/laboratory that is sery. According to a CDC report, workers may be exposed up to 10 h per steam-humidified by a system in which nurses experienced upper respiratory day, 40 h per week for a working life- amines were added for corrosion con- distress and burning eyes after the cor- time without experiencing adverse trol. The average room concentrations rosion inhibitors CHA and morpho- health effects, even though there may of DEAE and CHA at 42% relative line were added to boiler water used be exceptions to these time frames humidity (RH) are 0.6 and 0.7 ppb, to humidify the wards (NIOSH, because of individual susceptibility, a respectively. At 61% RH, the average unpublished data). Associated follow

10 Journal of Chemical Health & Safety, July/August 2014 up reports for this particular incident One of the more scientifically sound ammonia, inorganic acids, and volatile were not found in this literature search studies on how amine concentration organic compounds (VOCs) present in so chemical concentrations and any may affect IAQ was reported by Lao.16 the system at the time of sampling. One other circumstances cannot be identi The study assessed exposure to CHA of the alternative additives contained fied. from a steam humidification system at morpholine which can react under cer A laboratory worker removing ani the East Carolina University School of tain conditions with NOx to form N mals from an inhalation chamber was Medicine Greenville, North Carolina. nitrosomorpholine (NMOR). The inadvertently exposed for less than 30 s Use of a gas chromatograph fitted with sampling results indicated that NO2 to DEAE at an estimated concentration a flame ionization detector allowed for concentrations did not exceed the 8 of 100 ppm (480 mg/m3). The indivi a lower detection limit of 0.08 mg CHA h time weighted average (TWA) eva dual developed nausea and vomiting per air sample. The results were com luation criteria. However, employees within 5 min. Other persons in the same pared to a material balance calculation might sporadically be exposed to room also complained of a nauseating designed to model the CHA concen NO2 concentrations which exceed odor but showed no ill effects.31 tration in room air to predict situations both the NIOSH recommended ceiling In September 1993, NIOSH con that could lead to a toxic event and limit and the OSHA and ACGIH short ducted a Health Hazard Evaluation make recommendations based on find term exposure limit (STEL). The envir (HHE) at the Veterans Administration ings. The methodology and scientific onmental sampling also indicated that Medical and Research Center, White approach provide a model that shows the potential for NMOR formation River Junction, Vermont. There had that air concentrations derived by existed during this process. All the been employee complaints of fatigue, gross material balance can be used to air concentrations determined for allergy symptoms, and eye, nose and predict measured values. Lao notes NO, nitric acid, and ammonia were throat irritation and it was known that that in this study a manual or malfunc below their relevant exposure limits. morpholine and CHA had been used in tioning dosing system could result in a The results of this investigation suggest the boiler system. Air, surface wipe and CHA concentration that significantly that elimination of DEAE and CHA steam samples were obtained from exceeds the 10 ppm OSHA standard from boiler cures alleviates symptoms. research laboratories for the two and might result in a toxic event to NIOSH was asked to investigate anti-corrosion chemicals. A small those exposed.16 employee complaints of building- sheet of plastic, which had been hang In 1996, the International Chemical related employee illnesses at Riverside ing in a research laboratory for several Workers Union (ICWU) requested County Regional Medical Center, Riv months, was also analyzed for the pre that NIOSH conduct a Health Hazard erside, California. It was believed that sence of these compounds. Several Evaluation (HHE) at Agrium U.S., the illnesses were caused by DEAE months later additional samples were Incorporated, Homestead Nitrogen present in boiler steam used to humi taken to include testing for morpho Operations (formerly Cominco Fertili dify air in patient care units in the line, CHA and formaldehyde. Morpho zers,Inc.),located in Beatrice, hospital. Symptoms included skin irri line and CHA were not detected in Nebraska.33 Employees reported tation, eye irritation, runny or stuffy either the air or wipe samples at con adverse health affects that included nose, headaches, and increased aller centrations which exceeded minimum rashes, headaches, upper respiratory gies. The tests did not detect any DEAE detectable concentrations of 0.002 irritation, skin irritation, vomiting, in the air. However, several interesting parts per million (ppm), and and disorientation. The symptoms facts support the premise that impro 0.005 ppm respectively but they were were attributed to exposure to a com per practices and/or design of the detected on the plastic sheet and in bination of diethylhydroxylamine, N humidification system can result if steam condensate samples. Very low isopropylhydroxylamine, cyclohexyla the system is not working properly or levels (<0.01 ppm) of formaldehyde mine (CHA), and diethylaminoethanol if proper standard operating proce were also detected in the area air sam (DEAE) used in the boiler feed water dures are not followed. The boiler ples from the research laboratories. prior to Agrium management attempt mechanics wore gloves made of neo Formaldehyde concentrations were ing to alleviate the problem by using prene and latex rubber while handling at or below what is generally consid alternative chemical additives. Symp DEAE. These materials will not keep ered ‘background’. The report does not toms abated after initiating the use of hands from being exposed to DEAE. indicate whether or not formaldehyde alternative chemical additives but The building had diesel-powered gen was used in any form in the sampled since no analysis was done until after erators and it is possible that diesel laboratory. The environmental sam the change was made to the alternative exhaust re-entered the building’s ven pling results indicate that employees chemical additives, the initial cause of tilation system and affected the hospi are not exposed to airborne morpho the symptoms could not be deter tal’s air quality. Despite the fact that line or CHA at concentrations above mined. The alternative additives con there was insufficient data to positively the minimum detectable concentra tained oxides of nitrogen (NOx) and link DEAE exposure with reported tions for these compounds. NIOSH other compounds of which there were symptoms, the employee’s symptoms recommendations included disconti also health concerns. So NIOSH pro were consistent with DEAE exposure. nuing direct injection of boiler conden ceeded to evaluate potential employee NIOSH investigators recommended sate for humidification.32 exposures to NOx, nitrosamines, that humidification with boiler steam

Journal of Chemical Health & Safety, July/August 2014 11 containing DEAE be discontinued.18 neutralizing amines in the humidified sion of the eyes, skin, and mucous The NIOSH reports notwithstanding, air stream is usually less than one- membranes, exposure to appreciable no Federal government regulations tenth of the regulated concentration concentrations of morpholine vapors exist governing the use of DEAE or in the steam. An independent risk can result in irritation to the eyes, nose, other amines in direct steam humidifi assessment study conducted for the and throat, and may produce tempor cation systems. Alkyl Amines Council of the American ary and reversible hazy or blurred Most of the time, exposures to volatile Chemical Society determined that vision. These symptoms disappear amines become apparent from NIOSH when DEAE was properly applied to when exposure to morpholine is termi Health Hazard Evaluation (HHE) a boiler system, the concentrations nated. Adequate ventilation should be reports. In light of how many building were consistently below 10 ppb in provided where a large quantity of steam systems use anti-corrosion room air humidified with DEAE-trea product is exposed, or where mists or amines, exposure incidents are rare ted steam and 100 ppb of DEAE was vapors are generated. occurrences and to date it appears that an acceptable air concentration.34 Conaway39 conducted a study to they have been due to either human evaluate the subchronic toxicity of error or a defective ventilation system. morpholine in Sprague-Dawley rats There are very few scientific studies to HEALTH RISKS OF CHRONIC to help further define potential long prove the correlate that proper proce EXPOSURE TO CORROSION term effects of lower concentrations, dures result in a safe environment. The INHIBITING AMINES and to determine a maximum tolerated literature clearly indicates that the dose (MTD). The inhalation toxicity of actual concentration of amines in the Animal studies have been conducted 25, 100 and 250 ppm morpholine was indoor air is measured in parts per bil to observe chronic exposure to neutra investigated by 6 hr/day, 5 day/week lion (ppb) versus parts per million lizing amines. No significant increase exposures for 13 weeks. A maximum (ppm). Grattan19 described a study that in the incidence of tumors was seen in tolerated dose for a rat 2-year chronic was conducted by a chemical product two strains of mice, one strain of rats, morpholine study was established at manufacturer to determine amine levels and one strain of hamsters that were 150 ppm on the basis of the data. in room air humidified with morpho tested for carcinogenicity by oral A similar study of morpholine was line, CHA and DEAE. The results were administration of morpholine. Mor conducted using Sprague-Dawley rats published in a peer reviewed journal. pholine inhalation exposure in rats at exposure concentrations of 0, 10, 50, Temperature and relative humidity did not increase the incidence of and 150 ppm for 6 h per day, 5 days per were maintained at about 50% RH tumors over that in controls and no week, over a period of 104 weeks. and 22–23 8C (71.6–73.4 8F). In gen data were available from studies in Gross pathology, and histopathology eral, increasing the concentration of humans on the carcinogenicity of mor were normal in the exposed groups amine in the steam resulted in higher pholine. The World Health Organiza and comparable to the control ani airborne amine concentrations. The tion (WHO) identifies morpholine as mals. There were no exposure-related maximum air concentration never ‘‘not classifiable as to its carcinogeni adverse changes any internal organ or exceeded 0.66 ppm amine which is sub city to humans.’’35 NIOSH established tissue. The incidences of neoplasia stantially below OSHA/ACGIH expo an immediately dangerous to life or were comparable among all groups sure limits. From this study, Grattan19 health (IDLH) concentration for mor (including controls), and were typical notes that proper feed, dosage, and con pholine of 1400 ppm.36 for the strain and age of rat used in this trol of amine condensate corrosion Under certain conditions, it is theo study. The results of this chronic expo inhibitors are critical to assure compli retically possible that DEAE (or sure study demonstrated that morpho ance with FDA, OSHA, and ACGIH related compounds) in boiler water line is neither carcinogenic nor guidelines regarding the levels of amine may be converted to nitrosamines, systemically toxic although these expo permissible in steam-humidified room which are suspected human carcino sures did result in local (ocular, nasal, air. Control is required to minimize gens. No experimental evidence exists and dermal) irritation, consistent with corrosion in steam and condensate sys to indicate whether this occurs.37 In a the known irritation properties of mor tems; to prevent unscheduled outages; 14-week study in which rats were pholine. At the reported levels of the and to optimize boiler efficiency by exposed to 0, 11, 25, or 76 ppm DEAE, present occupational and environmen reducing the corrosion byproducts temporary signs of mild to moderate tal exposures, morpholine does not returned to the boiler via the conden respiratory irritation were found to be seem to create any significant risk of sate return system. Unfortunately, there dose dependent and the no-observed systemic toxic effects. Local effects is no standard that can protect anyone effect-level was found to be 10 ppm. (irritation) of the eyes and respiratory from a situation where standard oper There were no signs of any systemic tract may occur in non-controlled ating procedures are not followed or toxicity.38 DEAE has a NIOSH IDLH occupational and incidental exposures from gross error in system operations. of 100 ppm.36 to high concentrations of airborne Primary injection steam constitutes On the basis of animal toxicity stu morpholine, and skin irritation may a very small fraction of the mass dies, the principal health hazard from result from contact with liquid (even flow of the humidified air stream. accidental exposures to morpholine is diluted) morpholine.40 Consequently, the concentration of a moderate to severe irritation/corro

12 Journal of Chemical Health & Safety, July/August 2014 Cyclohexylamine is suspected to study was taken to be that of Lynch day and 40 h week. The ACGIH have chronic toxicity as an animal or et al.44 Using the 1983 summary report Threshold Limit Values (TLV) are human mutagen although the ACGIH by NIOSH of the pathology seen in this the same as the PELs for these com 1 Threshold Limit Value (TLVs ) study, 25 ppm was a Lowest Observed pounds. Where steam is used for ster Appendix A4 states that it is ‘Not Clas Adverse Effect Level (LOAEL). In ilization of surgical instruments, the sifiable as a Human Carcinogen’. CHA order to minimize irritation symptoms, American Society for Hospital Central is not listed on National Toxicology a 15-min STEL of 10 ppm is recom Service Personnel (ASCHSP) has pub Program (NTP), International Agency mended.44 lished guidelines for allowable amine for Research on Cancer (IARC) or Short-term exposure limits (STEL) concentrations. The ASCHSP guide OSHA lists as a cancer-causing agent. supplement the TWA where there are lines also follow FDA limits for per The chemical is well known to be phar recognized toxic effects from higher missible amine levels in treated steam. macologically active, having sym exposures over the short-term. A STEL Many jurisdictions encourage manage pathomimetic activity.41,42 However, is defined as a 15-min TWA exposure ment to follow whichever are the more no data are available on human health which should not be exceeded at any protective criteria for their operation risks associated with long-term, low- time.45 (Table 1). level airborne exposure to these The FDA has approved morpholine, The Occupational Safety and Health amines and data to support that cyclohexylamine, and diethylami Administration (OSHA Hazard Com CHA is a suspected teratogen, muta noethanol for use in steam boilers munications Standard 29 CFR gen, and carcinogen are inconclusive. whose steam comes in contact with 1910.1200)50 states that employees food except for milk and milk pro have both a need and a right to know REGULATION OF NEUTRALIZING ducts. The Code of Federal Regulations the hazards and identities of the chemi AMINES 21 CFR 184.113946 allows maximum cals they are exposed to in the work levels of 10 ppm for morpholine and place. Under HCS, if a ‘‘Subpart-Z’’ The criteria for regulation of neutraliz cyclohexylamine, 15 ppm for DEAE, chemical exists in the workplace, the ing amines in steam boiler systems falls and 3 ppm for octadecylamine. No employee must be warned of the expo within environmental evaluation cri Federal government regulations exist sure, regardless of the level of the con teria for the workplace. The federal governing the use of DEAE or other centration and the degree of agencies responsible for these regula amines in direct steam humidification compliance with ‘‘safe’’ exposure limits. tions are (1) NIOSH for recommended systems. All existing standards are HCS 29 CFR, Subpart Z lists PELs for exposure limits (RELs), (2) ACGIH for based on ingestion not inhalation. It only two out of four common corro 1 Threshold Limit Values (TLVs ), and has been a convention in the water sion-inhibitor chemicals, DEAE (3) OSHA for permissible exposure treatment industry to follow FDA lim (10 ppm) and morpholine (20 ppm). limits (PELs). its for amine levels in steam used for Both are subject to the HCS rules and The OSHA regulates the maximum other purposes. The FDA allows regulations. Clarification letters to HCS PEL’s in humidified air for two of the 20 ppm total amine when any or all indicate that HCS does not apply to the three chemicals: diethylaminoethanol are used in combination, provided that general public and employees who may and morpholine promulgated for the individual limits are not exceeded. be incidentally exposed to the chemi protection of industrial workers. They The FDA allows only the use of cals in trace amounts from the humidi are not intended to protect members of ammonium hydroxide in processing fication system. the general public, which may include plants in which treated steam contacts The National Research Council children, the elderly, those in ill health, dairy products. Ammonium hydroxide (NRC) has established acute exposure and others who may be particularly is also included in the U.S. Department guideline levels (AEGLs) 1–3 for sensitive to the effects of these sub of Agriculture’s (USDA) list of ‘safe cyclohexylamine over a period of 8 h stances. NIOSH RELs relate to the and suitable ingredients’. Ammonium of 1.8 ppm, 2.7 ppm, and 9.5 ppm; the prevention of occupational disease.37 hydroxide is a substance affirmed as selection of these levels was based on a The ACGIH has published threshold ‘generally recognized as safe’ (GRAS) comprehensive study of Sprague-Daw limit values (TLV’s) for all three neu at 21 CFR 184.1139.46 FDA permits its ley rats.21 AEGL-1 is the airborne con tralizing amines. The limits are slightly use as a leavening agent, a pH control centration of a substance above which different; the PELs for these chemicals agent, a surface-finishing agent, and as it is predicted that the general popula are based on an 8-h day and 40-h a boiler water additive. The OSHA has tion, including susceptible individuals, week.36,43,44 set a 15-min exposure limit for gaseous could experience notable discomfort, A time-weighted average (TWA) ammonia of 35 ppm by volume in the irritation, or certain asymptomatic, exposure is the average airborne con environmental air and an 8-h exposure non-sensory effects that are reversible centration of a substance during a nor limit of 25 ppm by volume.47 and not disabling. AEGL-2 is the air mal 8–10 h workday. In relation to the However, OSHA, ACGIH, and the borne concentration of a substance establishment of an 8 h time weighted FDA have established the allowable above which it is predicted that average (TWA) limit value (average concentrations in air as 20 ppm for the general population, including exposure on the basis of a 8 h/day, morpholine; 10 ppm for CHA and susceptible individuals, could experi 40 h/week work schedule) the key 10 ppm for DEAE based on an 8 h ence irreversible or other serious,

Journal of Chemical Health & Safety, July/August 2014 13

Table 1. Comparison of chemical additive regulations for steam versus milk or milk products.

long-lasting adverse health effects or condensate holding tank. If corrosion amines in room air are in parts per an impaired ability to escape. AEGL-3 inhibitors are needed, the condensate billion, far below the acceptable levels. is the airborne concentration of a sub tank is infused with a small amount of CHA concentration is positively stance above which it is predicted that makeup water mixed with the neutra associated with the amount of humi the general population, including sus lizing amines. High-performance dification and the CHA concentration ceptible individuals, could experience liquid chromatography (HPLC) or in the steam, and negatively associated life threatening health effects or death. gas chromatography can be used to with the raw air temperature and No AEGL levels have been established directly measure amine concentrations humidity decreases of the room air 21 for morpholine or DEAE. in steam samples upstream from the after heating and humidifying. Fluctua The USDA no longer issues separate point of steam release into ambient air; tions in humidification are small, but regulations for meat, poultry, egg and however, they are complex and time- the design of some steam systems can fish processing plants under its jurisdic consuming procedures. CHA concen greatly affect CHA concentration in tion. These limitations were previously tration can be approximated using a steam. Material balance can be used listed under older USDA guidelines, as material balance calculation under the for real-time modeling if the necessary ‘‘G6’’ and ‘‘G7’’ compounds.51 These assumption that there is no significant variables are constantly monitored and older USDA limitations have all been internal source of humidity, no inter the effect of internal removal is known. replaced by the limits found in Title 21, nal CHA source, and no significant Sections 173.31048 and 184.113946 of internal removal of CHA. This the Code of Federal Regulations. 21 approach does not take into account CAREFUL MAINTENANCE, CFR 173.31048 lists the various boiler the internal removal of CHA through CONTROLS AND MONITORING water additives, approved by the FDA, sorption and other unknown means. for use in the preparation of steam, A simple mass balance calculation The feed rates of neutralizing amines when the steam will contact food or (such as that used by Edgerton29) for are controlled in the field by in-plant food packaging. This regulation also DEAE, CHA and morpholine shows testing for condensate pH. When spells out the conditions where these for example, that if the room condition maintained in a slightly alkaline range approvals are applicable. is maintained at 75 8F and humidity at (7.5–9.0 pH), condensate will be rela 50% the steam concentration would tively non-corrosive to system metals. MEASUREMENT AND MONITORING need to be over 1000 ppm for CHA, However, maintaining pH in this range OF CORROSION-INHIBITING AMINES 1600 ppm for DEAE, and 2000 ppm is no guarantee that amine levels in the for morpholine in order to reach steam are within acceptable limits for a Measurement of CHA concentration OSHA PELs. Studies conducted by regulated application. When it is The water used to generate steam Lao16 and Edgerton29 indicate that necessary or desirable to determine if for humidification originates in the the concentration values of these amine levels are in compliance with

14 Journal of Chemical Health & Safety, July/August 2014 government regulations or published control point most likely to influence corrosion in systems of various lengths. guidelines, laboratory analysis of the the occurrence of a toxic event arising It is fairly easy to control their indoor air steam is required. To assure accurate from humidification with steam con concentrations well below accepted results from a laboratory amine analy taining volatizing amine corrosion exposure limits through the use of sis, care must be taken to follow very inhibitors. Lao notes that the auto standard operating procedures and specific procedures for collection and matic feed device should be carefully practices. shipment of steam samples. maintained and manual dosing of the The Environmental Protection When corrosion-inhibiting amines boiler should not be allowed in the Agency (EPA) has issued strong warn are added to boiler water using proper event that the automatic dosing equip ings regarding boiler chemicals.14,15 techniques and at concentrations ment is inoperable. This conclusion is Steam used for humidification is not required to prevent condensate system also supported by Malaiyandi et al.52 ingested but inhaled. Since no Federal corrosion, studies have shown that the His research shows that where inter government regulations exist govern amine level in the steam-humidified air mittent manual dosing is used rather ing the use of amines in direct steam falls well below the PEL for the amine. than constant mechanical dosing, the humidification systems (other than in Grattan et al.19 describes steam level of corrosion inhibiting amines in the food industry in which all the exist humidification tests conducted by condensate can to rise over ing standards and guidelines are based Nalco for commonly applied amines 10,000 ppm for periods of more than on ingestion) the water treatment under controlled conditions. It has 10 h. industry tends to follow FDA limits determined that concentrations in In order to assure compliance with for amine levels in steam used for room air normally are well below pre FDA, OSHA, and ACGIH guidelines direct steam humidification systems scribed federal limits if sound applica regarding the levels of amine permis for other purposes. tion techniques are followed. Even sible in steam-humidified room air, The literature is full of examples when the concentration of morpholine minimize corrosion in steam and con where the concentration of amines in in the steam was increased to densate systems, and prevent unsched the indoor air is measured in parts per 64.8 ppm, the airborne concentration uled outages and optimize boiler billion (ppb) versus parts per million in the humidified air remained as low efficiency by reducing the corrosion (ppm), the measurement used by U.S. as 0.018 ppm, a level far in excess of byproducts returned to the boiler via regulatory agencies for allowable con that required for condensate system the condensate return system, it is cri centrations in air. The evidence corrosion inhibition; this is again far tical to monitor the proper feed, strongly suggests that the concentra below the amine PEL.19 dosage, and control of amine conden tion of amines in indoor air where The recommendations from the sate corrosion inhibitors. Feed rate humidification is controlled using Nalco study19 discussed by Grattan controls include tank level sensors, steam created with ‘treated water’ is included continuously monitoring for pump controllers and flow sensors. negligible, far below the acceptable corrosion problems and process leaks pH and conductivity of the steam PEL levels currently adhered to for in steam/condensate systems. The can be measured using on-line analy IAQ and not a health risk to building entire system should be sampled at zers. Coupons or sample ports placed occupants when the chemical addi multiple locations to determine system strategically, allow for frequent check tives are injected automatically; in conditions. Samples should be cooled ing for corrosion products. The point industry accepted concentrations; to below 90 8F to prevent flashing off of chemical injection should be located and monitored regularly per standard the dissolved gases and amines. Con in an accessible area. Coupons, how operating procedures. densate samples should be tested for ever, allow water to be lost from the The way in which corrosion inhibi pH, conductivity, corrosion products, system, and oxygen is added, every tors are added to boiler systems dissolved oxygen, and carbon dioxide. time the coupon rack is opened. Other appears to affect the risk of toxic expo The presence of other contaminants control techniques include continuous sure. It is recommended that volatizing should also be evaluated. These might feeding of chemicals via metered feed amines be used in systems with well- include water hardness, silica, and pumps; not permitting slug feeding; maintained automatic dosing devices. organics, and iron and copper levels. daily checking and adjustment of the Manual dosing should not be allowed The methods used to add corrosion feed rates. when automatic dosing equipment is inhibitors to boiler systems appear to inoperable because of the possibility of affect the risk of toxic exposure. human error. Investigators should Although average amine concentra CONCLUSION consider applying the material balance tions in humidified air can be kept calculations in the design of hospital low, it is extremely important that The most common neutralizing amines steam humidification systems to avoid volatizing amines only be used with used in steam boiler humidification loss of the amine additive through well-maintained automatic dosing systems in health care facilities are volatilization. The material balance devices to prevent toxicity. The study cyclohexylamine (CHA), diethylami may be used for real time modeling if reported by Lao16 supports the use of a noethanol (DEAE), and morpholine. the appropriate variables are con material balance approach to identify Used individually or in combination, stantly monitored and the effect of the additive feed mechanism as the they are capable of preventing internal removal is known.

Journal of Chemical Health & Safety, July/August 2014 15 Low ambient air amine concentration 4. Food and Drug Administration (FDA). 14. Environmental Protection Agency (EPA) levels can be effectively managed with careful Code of Federal Regulations CFR 21, Part and National Institute of Occu- pational maintenance and monitoring, including 211. Current Good Manufacturing Practice Safety and Health (NIOSH). Building Air metered introduction of the treatment for Finished Pharmaceuticals. 2013, At: Quality: A Guide for Building Owners and chemicals into the steam system. Practical http://www.accessdata.fda. Facility Man- agers. EPA/400/1-91/033; considerations to achieve low ambient air amine gov/scripts/cdrh/cfdocs/cfcfr/CFRS Environ- mental Protection concentration levels include: earch.cfm?CFR Part=211 (accessed Agency; Washington, DC, 199128. • Continuous feeding of chemicals via 02.11.13). 15. Environmental Protection Agency (EPA). metered feed pumps 5. US Pharmacopeia 2013 Edition. Appendix B: HVAC Systems and Indoor At: http://www.gobookee.org/us- Air Quality. EPA SN-005- 000-00390; • Not permitting slug feeding pharmacopeia-2013-edition/ (ac- EPA; Washington, DC, 1992. • Daily checking and adjustment of the cessed 02.11.13). 16. Lao, Y. J. An assessment of exposure to feed rates 6. Division of Technical Resources. La- cyclohexylamine arising from steam Measure pH and conductivity using • boratory Water Its Importance and humidification of indoor air. J. Envir- on. on-line analyzers Application; Office of Research Facil- Health, 1993, 56(December (5)), • Providing coupons and/or sample ities, National Institutes of Health, March 1–7. ports to enable frequent checking 2013 At: http://orf.od.nih.gov/ 17. Centers for Disease Control and Pre-

PoliciesAndGuidelines/Documents/ vention. Workplace exposures to cor- Unfortunately, there is no standard that DTR%20White%20Papers/Laboratory rosion-inhibiting chemicals from a can protect anyone from a situation where standard operating procedures are not %20Water-Its%20Importance%20 steam humidification system. Morbid- ity followed or from gross error in system and%20Application-March-2013_508. pdf and Mortality Weekly Report, vol. 39, no. operations. When corrosion-inhibiting amines (accessed 02.11.13). 47 (pp. 863–865). 1990, p. 863– are added to boiler water using proper 7. Spence Engineering Company, Inc.. 865. techniques and at concentrations required to Spence Steam & Fluid Control De- 18. Cook, C. K.; Malkin, R. Health Hazard prevent condensate system corrosion, studies signer’s Guide. Clean Steam Design Evaluation Report 2000-0169-2854. have shown that the amine level in the steam- Guidelines; Spence Engineering Com- Riverside County Regional Medical humidified air falls well below the PEL for pany, Inc., 2013353 At: http://www. Center: Riverside, CA, 2001 September. the amine. With careful monitoring of water vaptec.ca/pdfs/cataloguespence.pdf 19. Grattan, D. A.; Koutek, M. E.; Russum, chemistry, along with direct testing for amine (accessed 02.11.13). S. A. Amine levels in steam-humidified air levels in the humidified air space, and 8. Butler, M. A.; Colucci, S. R. Steam engineered systems. Engineered Systems, careful risk assessment operators of steam humidification in pharmaceutical fa- September/October (pp. 70– 74). 1989, p. humidification systems can be assured that room cilities. Engineering Systems Magazine. 70–74. air amine levels will be well below that 2008, September. 20. American Conference of Governmental necessary to cause adverse effects in humans. 9. Roscioli, N.; Vargo, S. Materials, sur- Industrial Hygienists, Inc.. Documenta- tion faces, finishes and components for of the Threshold Limit Values and sanitary applications. Pharmaceutical Biological Exposure Indices; ACGIH; REFERENCES Manufacturers Association Water Cincinnati, OH, 1991462. 1. Koch, G. H. ; Brongers, M. P. H.; Seminar. Atlanta, GA, 1982, . 21. National Research Council. Appendix Thompson, N. G.; Virmani, Y. P.; Payer, 10. Food and Drug Administration 3 Cyclohexylamine Acute Exposure J. H. Cost of corrosion in the USA. (FDA). Code of Federal Regulations 21 Guideline Levels. Acute Exposure U.S. Federal Highway Ad- ministration CFR 177.2600 Chapter I, Part 177, Guideline Levels for Selected Airborne (FHWA), Report FHWA-01-156, Subpart B, Section 177.2600 ‘‘Rubber Chemicals: Volume 5; The National September. 2001, At: articles intended for repeated use’’, 21 Academies Press; Washington, DC, 2007. http://corrosionda.com/summary.htm CFR 177.1520, 21 CFR 175.105 22. Occupational Safety & Health Admin- (accessed 02.11.13). ‘‘Adhesives’’, and 21 CFR 177.1210 istration (OSHA). Chemical Sampling 2. Bingaman, J.; Turpin, J. Direct steam- ‘‘Closures with sealing gaskets for food Information; OSHA; Washington, DC, injection humidification: is it safe for containers’’. 2008, At: http://www.osha.gov/dts/ building occupants? Engineered Sys- tems. 11. Food and Drug Administration (FDA). chemicalsampling/data/CH_255600. html 2001, At: www.esmagazine.com/ Code of Federal Regulations CFR, Title (accessed 02.11.13). CDA/ArticleInformation/features/ 21, Chapter I, Part 177, Subpart B, 23. Eichelbaum, M.; Hengstman, J. H.; Rost, BNP__Features__Item/0,2503,23246, Section 177.2510 ‘‘Polyvinylidene fluoride H.; Brecht, T.; Dengler, H. J. 00.html (accessed 02.11.13). resins’’. Pharmacokinetics, cardiovascular and 3. 2010 California Mechanical Code. At: 12. Latham, T. ‘Clean Steam in the Phar- metabolic actions of cyclohexylamine in http://www.iapmo.org/Pages/2010Ca- maceutical Industry,’ PDH Course K109. man. Arch. Toxicol. 1974, 31, 243–263. liforniaMechanicalCode.aspx (ac- At: http://www.pdhcenter. 24. Lundqvist, G. R.; Yamagiwa, M.; Ped- cessed 02.11.13). com/courses/k109/k109content.pdf ersen, O. F.; Nielsen, G. D. Inhalation of (accessed 02.11.13). diethylamine – acute nasal effects and 13. The California Code Application No- tice subjective response. Am. Ind. Hyg. Assoc. (CAN) #4-408.1.5 Chapter 4 Ven- tilation J. 1992, 53, 181–185. air Supply; Section 408.1.5, Exception 25. European Commission. Recommenda- Effective: 6/19/2008 Re- vised: tion from the Scientific Committee on 6/29/2011. At: http://www. oshpd.ca.gov/fdd/Regulations/CANs/ 2010/4-408.1.5.pdf (accessed 02.11.13).

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