Safety Bulletin U.S. Chemical Safety and Hazard Investigation Board

No. 2003-03-B Reprinted SODIUM HYDROSULFIDE: PREVENTING H ARM November 2004

Introduction Sodium Hydrosulfide ince 1971, reported incidents involving liquid solutions of sodium Common synonyms: S hydrosulfide (NaHS) have resulted in 32 deaths and 176 injuries, most NaHS (NaSH) notably in the leather tanning and pulp and paper industries. The most Sodium bisulfide serious safety concern associated with NaHS is its capacity to produce Sodium sulfhydrate large amounts of deadly hydrogen sulfide gas (H2S) when it reacts with an Sodium hydrogen sulfide acid or is exposed to high heat. Sodium mercaptan

Despite its pungent rotten egg odor, H2S can deaden the nerves that detect CAS No.: 16721-80-5 odors, thereby preventing those exposed from being able to smell life- UN No. (solution): 2922 threatening airborne concentrations. This condition is referred to as (Figure 2) “olfactory fatigue” and must be considered when designing NaHS safety systems. DOT Hazard Class: 8 (Figure 2) This Safety Bulletin is published to increase awareness of the hazards EPA Hazardous Waste No.: associated with NaHS and to outline safety practices to minimize the D003 potential for harm to workers and the public.

with an acidic solution to Defining the Figure 1. Emergency produce H2S. responder in NaHS and H2S Problem Absent or inadequate protective gear. engineering controls, such as NaHS releases highly toxic H S if 2 ventilation or H2S detection mixed with an acid or if exposed to devices, coupled with excessive heat. Because it is inadequate PPE. corrosive, it is also potentially harmful to the skin and eyes.1 Inappropriate emergency response actions by workers and NaHS incidents typically involve emergency responders (Figure 1). the following three elements: This bulletin reviews selected An inadvertent spill, leak, or NaHS incidents that caused death mixing, whereby NaHS reacts and injury, for example:

Delivery drivers inadvertently transferring NaHS into acid storage tanks. (See Whitehall 1 Although this bulletin addresses the hazards associated with NaHS solutions, Leather, Horween Leather, and its precautions also apply to other Prime Tanning case studies on sulfide-containing substances (e.g., sodium sulfide), which are often used pages 13–15.) interchangeably with NaHS, and which

also generate H2S when mixed with acids. 2

CSB identified the following two Table 1 summarizes the general Figure 2. Shipping common management failures physical properties of NaHS placard with UN number during its review of catastrophic solutions. and DOT hazard class. NaHS-related incidents:2

Failure to identify and mitigate hazards during process system Table 1 design and engineering. Physical Properties of NaHS

Failure to manage hazards that Molecular weight: 56.1 were not controlled through Specific gravity:

good design and engineering. 1.152 (a)–1.376 (b) pH of solution: strongly alkaline (11–12) Physical Solution freezing point: -15ºC (a) – 40ºC (b) Characteristics Odor: rotten egg NaHS being allowed to mix with H S flammable limits acids in plant sewer systems. and Uses of NaHS 2 (% H S in air): (See Georgia-Pacific and 2 Lower: 4 Westvaco case studies on pages Typical NaHS solutions are pro- Upper: 44 13-14.) duced commercially by combining

H2S with caustic soda (NaOH), as (a) 22% solution. Mixing of NaHS and an acid shown in the following reaction: (b) 60% solution. inside a common spill containment. (See Powell H2S + NaOH NaHS + H2O Duffryn case study on page 13.) NaHS is used in a variety of industries (Figure 3): The resulting finished solution has a pH of approximately 11.5. In the pulp and paper industry, Depending on its solution strength to remove lignin from wood (22 to 60 percent NaHS), it is chips. heated to 71 to 82 ºC to prevent In mining, as a flotation agent to CSB Safety Bulletins offer advisory crystallization. NaHS is sold information on good practices for separate impurities. managing chemical process hazards. commercially in both solution and Case studies provide supporting flake forms, with solutions In manufacturing, as a raw information. CSB Investigation accounting for about 80 percent of material or purifying agent. Reports comprehensively review all total U.S. production.3 the causes of an incident. In the leather-tanning industry, to remove hair from hides.

U.S. Chemical Safety and Hazard 2 Investigation Board CSB compiled the incident data and Office of Investigations safety practices described throughout this Safety Bulletin during a compre- 2175 K Street NW, Suite 400 hensive review of NaHS incidents and Washington, DC 20037-1848 industry handling practices. 202-261-7600 3 Total U.S. production for all forms of http://www.csb.gov NaHS was approximately 269,000 tons in 2003. 3

Figure 3. NaHS use by industry sector.

Leather tanning Miscellaneous Pulp & paper 10% 5% 42%

Chemical & dye manufacturing 13%

Copper flotation 30% The Innovation Group

ACGIH: American Conference of Governmental MSDS: Material safety data sheet Industrial Hygienists Na: Sodium AIChE: American Institute of Chemical Engineers NaHS: Sodium hydrosulfide AIHA: American Industrial Hygiene Association NaOH: Sodium hydroxide ANSI: American National Standards Institute NAS: National Academy of Sciences ASSE: American Society of Safety Engineers NFPA: National Fire Protection Association ATSDR: Agency for Toxic Substances and Disease NIOSH: National Institute for Occupational Safety and Registry, DHHS Health, DHHS ºC: Degrees Celsius NLM: National Library of Medicine, National Institutes CAS: Chemical Abstracts Service of Health (NIH), DHHS CCPS: Center for Chemical Process Safety, AIChE NRC: National Response Center, USCG CDC: Centers for Disease Control and Prevention, NTSB: National Transportation Safety Board DHHS OSHA: Occupational Safety and Health Administration, CFR: Code of Federal Regulations U.S. Department of Labor

CO2: Carbon dioxide PEL: Permissible exposure limit, OSHA CSB: U.S. Chemical Safety and Hazard Investigation pH: Potential of hydrogen Board PPE: Personal protective equipment DHHS: U.S. Department of Health and Human ppm: Parts per million Services PSM: Process safety management, OSHA DOE: U.S. Department of Energy PTFE: Polytetrafluorethylene DOT: U.S. Department of Transportation REL: Recommended exposure limit, NIOSH EPA: U.S. Environmental Protection Agency SCBA: Self-contained breathing apparatus

ERPG: Emergency Response Planning Guidelines, AIHA SO2: Sulfur dioxide H: Hydrogen STEL: Short-term exposure limit

H2O: Water TWA: Time-weighted average

H2S: Hydrogen sulfide UN: United Nations HazCom: Hazard communication, OSHA USCG: U.S. Coast Guard IDLH: Immediately dangerous to life or health WEEL: Workplace emergency exposure limit, AIHA MIT: Massachusetts Institute of Technology 4

Eye Contact result in “gas eyes” or “sore eyes,” Health Hazard with symptoms of scratchiness, Summary Corrosivity hazard irritation, tearing, and burning. Because of the high pH of NaHS Symptoms are likely to disappear Because NaHS is corrosive, it solutions (approximately 11.5), when the exposure ends. Pro- presents a hazard to unprotected contact may severely irritate and longed exposure to concentrations 4 skin and eyes. However, its most burn the conjunctiva and cornea, of H2S above 50 ppm may cause serious hazard is its propensity to and may result in permanent tissue permanent damage or intense tearing, blurring of vision, and produce toxic H2S gas when mixed damage. with an acid or exposed to high heat pain when looking at bright light.

sources such as a fire. The acid Hazard from generated H2S reaction chemistry is shown as: Exposure to low concentrations of Skin Contact

+ + H2S over several hours or days may Skin contact with NaHS may NaHS + Acid (H ) Na + H2S produce pain, irritation, redness 4 Inhalation The conjunctiva and cornea are the thin, (erythema), or burns. Because the transparent tissues that cover the outer symptoms of exposure severity may surfaces of the eye. The gases released by NaHS are corrosive and may contain high

levels of H2S. Inhalation of H2S is Table 2 irritating to the nose and throat. Inhalation of H2S At higher concentrations, it can Concentration produce olfactory fatigue, a (ppm) Health Effects (a) buildup of fluid in the lungs (pulmonary edema), severe 0.05 Rotten egg odor detectable by most humans. shortness of breath, and death. 0.13–30 Obvious and unpleasant odor. Table 2 outlines the health effects of inhaling H S. 50–150 Olfactory fatigue (temporary loss of smell) and marked 2 dryness and irritation of nose and throat. Prolonged exposure may cause runny nose, cough, hoarseness, H S exposures may headache, nausea, shortness of breath, and severe lung 2 damage (pulmonary edema). cause olfactory fatigue 200–250 Worsening and more rapid onset of the above health Continuous exposure to low effects; possible death in 4 to 8 hours. concentrations (5 to 10 ppm) 300–500 Excitement, severe headache and dizziness, staggering, of H S or brief exposure to unconsciousness, and respiratory failure likely in 2 5 minutes to 1 hour; possible death in 30 minutes to higher concentrations (above 4 hours. 50 ppm) deadens the odor- detecting nerves in the nose and 500+ Rapid onset of severe toxicity, respiratory paralysis, and death. If not fatal, may cause long-term effects such as lessens the ability to smell memory loss, paralysis of facial muscles, or nerve tissue dangerous concentrations. The damage. higher the concentration of 800–1,000 May be immediately fatal after one or more breaths, H2S, the faster the onset of resulting in an instant unconsciousness or “knock-down” olfactory fatigue. effect.

(a) Data from NIOSH, NLM, and ATSDR. 5 be delayed, affected skin should be treated immediately. (See the first Figure 4. NaHS incidents* by industry sector. aid guidance on page 12.)

Ingestion Leather tanning Refining Unknown 1 Pulp & paper Ingesting a small amount of NaHS 5 1 14 in a single dose will likely produce Other only minor throat irritation or 6 burning of the esophagus. Ingesting a larger quantity, however—or small quantities over an extended period—may seriously damage the gastrointestinal tract. In addition, NaHS that mixes with Manufacturing stomach acids produces H2S and Transportation 6 may cause the health effects asso- 12 ciated with inhalation (Table 2). *An “incident” is a NaHS-related event involving a fatality, injury, medical evaluation, or evacuation. Incident Data Thirty-six of the incidents resulted Although the incidents reviewed From reported data for the United from H2S releases, and the remain- are not all-inclusive, their number States from 1971 through 2004, CSB der from skin or eye exposure to and severity clearly indicate that identified 45 NaHS-related NaHS solutions. NaHS presents a serious hazard in incidents in six industry sectors the workplace. (Figure 4).5 Collectively, these The following causal categories incidents resulted in: were identified during this review: Prevent Harm 32 fatalities. Improper mixing or transfer: 15 (33 percent). Good safety management includes 176 injuries. Spills: 12 (27 percent). identifying and evaluating hazards 351 medical evaluations. during initial process planning Mechanical failure: 7 and design, and continues At least 10 plant or community (16 percent). evacuations. throughout the life cycle of the Improper maintenance or repair: operation—both for new processes 6 (13 percent). and for modifications. This 5 approach allows managers and The earliest recorded NaHS incident Five of the 45 incidents (11 percent) identified during the CSB review employees to understand and were attributed to unknown occurred in 1971. Regulatory reporting address hazards prior to startup. requirements and industry usage causes. practices have changed significantly Hazard control measures such as since that time, which may account for Incident data were obtained from incident rate fluctuations among the work practice controls and PPE are OSHA, EPA, and ATSDR various industry sectors. For example, secondary layers of protection. nearly all of the leather-tanning databases, as well as industry incidents occurred between 1971 and They should be considered only questionnaires, interviews, and 1990, and no transportation incidents after attempting to eliminate were reported prior to 1990. The media sources. Only those hazards through design and incidents CSB reviewed include incidents that were reported and pulping-liquor incidents in which NaHS engineering, or when substituting was used as the sulfide source. accessible are represented. 6

for a less hazardous material or Investigation Report, Improving storage areas and offloading process is impractical. Reactive Hazard Management [2002; terminals). http://www.csb.gov].) A multidisciplinary team applying Design storage tank vents to minimize the potential for established process safety Design to Eliminate management principles should worker exposure. identify and evaluate hazards. Hazards Design transfer connections and These principles are outlined in the Process systems must be designed procedures to prevent inadver- OSHA Process Safety Management to prevent NaHS from inadver- tent mixing. Limit access to of Highly Hazardous Chemicals tently mixing with acidic solutions. these connections to trained and (PSM) Standard and in CCPS The potential for human error authorized personnel through publications listed at the end of during handling should be reliable and effective controls, this bulletin. identified and eliminated to the which should include The PSM Standard regulates maximum extent practicable. procedures and physical barriers (e.g., locking devices or unique processes containing threshold Interviews and literature reviews fitting configurations). quantities of highly hazardous with NaHS manufacturers, trade chemicals, explosives, and associations, and industry Construct process system flammable liquids in amounts representatives highlighted the components from materials 6 exceeding 10,000 pounds. NaHS following design practices: capable of withstanding the is not a PSM-covered chemical corrosivity and temperatures Always treat sewers as because—despite its reactive associated with NaHS solutions. extensions of the process. Do potential to produce large amounts NaHS manufacturers NOT add wastes without of H2S when mixed with acids or recommend the following analyzing for compatibility with when exposed to heat—it does not materials:8 meet the OSHA listing criteria. other sewer contents. Storage tanks and steam Separate acid- and NaHS- CSB has recommended that OSHA coils: 304 stainless steel. expand PSM to include chemicals containing waste streams, or with reactive characteristics similar design the system to handle Pumps: 304L or 316L to those exhibited by NaHS (i.e., mixing so as to prevent an stainless steel. uncontrolled or otherwise relatively stable chemicals that Packing: PTFE-impregnated hazardous release of H S. react dangerously with other 2 carbon fiber. 7 substances). (See the CSB Hazard Construct separate containments Piping: 304L stainless steel, for NaHS and acid storage insulated and heat-traced in containers and process locations where freezing may equipment. occur. If waste NaHS and acids are 6 Gaskets: Spiral-wound 316L See 29 CFR 1910.119 at mixed in a sewer, install waste- http://www.osha.gov/SLTC/ stainless steel or a PTFE ring. processsafetymanagement/. Highly stream/sewer monitors with hazardous chemicals are listed in alarms to warn employees of Plug valves: Lubricated or Appendix A. system upsets or unfavorable made with a PTFE sleeve and 7 Based on their reactive characteristics, the chemicals included in Appendix A acid conditions. seal. were selected from the 1975 version of NFPA 49, Hazardous Chemical Data. Install ventilation systems and 8 This information illustrates the types of OSHA selected only those chemicals with H S detectors and alarms at materials manufacturers recommend for instability ratings of “3” or “4” (on a 2 use in NaHS process systems. It is not scale of 0 to 4). These ratings focus locations where hazardous intended as a substitute for recognized purely on the chemicals themselves and concentrations may occur (e.g., and generally accepted good engineering do not consider the consequences of practices for the specific facility design, mixing with other chemicals. construction, or maintenance. 7

how to protect themselves from accomplished during a facility z H2S hazard: separate NaHS and acids adverse health effects due to safety orientation. chemical exposure. The general requirements of this standard are Provide personal protective Allowing spilled NaHS to outlined at http://www.osha.gov. equipment inadvertently mix with an acid (pH < 7) poses a significant risk The HazCom requirements Facilities should rely on PPE only of harm. Similarly, if a sewer pertaining to NaHS MSDSs and after conducting a hazard system is not designed to control H2S training are outlined below: assessment, as required by the

H2S, allowing NaHS to run off to z MSDSs: Employers are required OSHA Personal Protective a sewer containing acids also to obtain an MSDS for each Equipment, General Requirements 13 poses a significant risk. Large hazardous chemical (present or Standard (29 CFR 1910.132). amounts of toxic (and flammable) produced at the facility) and to Employees should participate in

H2S may evolve very rapidly! make them readily available to the selection of PPE because of the workers. The information potential for stress and discomfort Manage Hazards contained in MSDSs may vary created by restrictions to move- significantly among NaHS ment, vision, and dexterity. Where Eliminating hazards through manufacturers.10 Operations and practical, PPE should be simple to process design and engineering is safety personnel should, operate and reasonably the optimal hazard management therefore, attempt to acquire a comfortable to wear for the system. However, additional better understanding of NaHS duration of the exposure. systems are required when design hazards through such resources z Chemical protective clothing: and engineering do not eliminate as this Safety Bulletin, MSDSs PPE required to protect workers these hazards. CSB identified the and product information from from the corrosive hazards following management systems as multiple NaHS manufacturers, associated with NaHS includes particularly applicable to NaHS and databases such as the NLM eye and face protection, chemical users.9 Hazardous Substance Data protective gloves, protective 11 Base. clothing, and foot protection Communicate hazards to (http://www.cdc.gov/niosh). employees z Training: Employers are required to train their employees z Respiratory protection: Before The OSHA HazCom Standard (29 and inform contractors relying on respirators, facilities CFR 1910.1200) is based on the (including delivery drivers, must have determined that it is simple concept that employees construction workers, and impractical to eliminate or have both a need and a right to emergency responders) of site- control exposures through know of the hazards associated specific NaHS and H2S hazards, substitution of a less hazardous with chemicals to which they are including plant hazard labeling chemical, design and exposed. They also need to know systems and locations of engineering controls, or work 12 MSDSs. This is often practice or administrative controls. If respiratory protection is required, employers

10 must comply with the OSHA 9 The safety programs outlined in this See http://www.csb.gov and section relate to circumstances identified http://www.osha.gov for discussions of Respiratory Protection Standard in the incidents CSB reviewed. Other MSDS inconsistencies and inaccuracies. (29 CFR 1910.134).14 relevant safety programs—such as 11 http://toxnet.nlm.nih.gov/index.html. 12 management of process change, line See Safety Requirements for H2S Training breaking, lockout/tagout, and process Criteria (ANSI Z390.1-1995, available at 13 http://www.osha.gov/SLTC/ and equipment integrity—are also http://webstore.ansi.org/ansidocstore/ personalprotectiveequipment/. 14 extremely important components of a default.asp) for a model H2S training http://www.osha.gov/SLTC/ successful accident prevention program. program. respiratoryprotection/). 8

15 NIOSH has certified certain Stationary H2S detection negative-pressure, air purifying and notification systems:

respirators for use where H2S These systems provide alarm concentrations exceed the OSHA notification 24 hours a day PELs (Table 3).16 For situations and can be used to auto- where concentrations are matically notify emergency unknown or exceed equipment responders. Freestanding Table 3 protection limits, NIOSH solar- and battery-powered prescribes supplied-air systems are also available H2S Exposure Limits (ppm) respirators. These requirements that can be equipped with OSHA (PEL) are outlined in the NIOSH Pocket radio transmitters to send Ceiling(a) 20 Guide to Chemical Hazards (2003; real-time monitoring results 10-minute peak (b) 50 http://www.cdc.gov/niosh/ to a remote alarm or warning NIOSH npg/npg.html). device. IDLH (c) 100

REL 10 Air monitoring for H2S: In

(10-minute ceiling) (d) environments that are normally Enter confined spaces safely ACGIH safe, but which pose the risk of Because H2S is heavier than air, it 15-minute STEL (e) 15 hazardous H2S exposure, the tends to concentrate near or below 8-hour TWA 10 only way to ensure worker safety ground level, especially where is to continuously monitor the there is limited air movement. (a) Concentration generally not to be air. In recent years, H S monitors exceeded during the work shift. 2 Sump pits, storage and process have become much smaller, more (b) Workers may be exposed above the tanks, valve trenches, and sewers ceiling level up to this concentration rugged and reliable, simpler to are particularly susceptible to high for a maximum of 10 minutes. operate, and much less expen- concentrations of H2S and may (c) Exposure to environments exceeding sive. Examples of available this airborne concentration is likely to require atmospheric testing, cause death or permanent adverse devices are noted below: communications equipment, and health effects or to prevent escape. standby emergency rescue Use of SCBA in pressure-demand or Personal H2S detectors with positive-pressure mode is required audible, vibrating, and personnel. (see 29 CFR 1910.134). visual alarms: These (d) Exposure should not exceed the REL OSHA regulates confined spaces in for any continuous 10-minute period detectors can be clipped into the Permit-Required Confined during the work shift. a shirt pocket or worn on a Spaces Standard (29 CFR (e) Exposure should not exceed this level hard hat. They are relatively 17 for any continuous 15-minute period 1910.146). Further information during the work shift. inexpensive and reliable, on this standard is provided in the and have low-maintenance references section of this bulletin. electrochemical sensors and long-lasting batteries.

15 OSHA relies on NIOSH as the testing and certifying body in 29 CFR 1910.134. NIOSH requires end-of-service life indicators for filters used to protect against chemicals with poor warning

properties, such as H2S. 16 See Table Z-2, 29 CFR 1910.1000, http://www.osha.gov/pls/oshaweb/ owadisp.show_document?p_table= 17 http://www.osha.gov/SLTC/ STANDARDS&p_id=9991. confinedspaces/. . 9

Handle and store NaHS safely Warning against exposure of risk of exposure, adequacy of NaHS to excessive heat or available shelters, evacuation The hazards associated with NaHS storage near open flames or other time requirements, and other require employers to establish ignition sources that might factors such as the charac- facility-specific safe handling and generate or ignite flammable H2S. teristics of the chemical released storage practices and procedures and weather conditions. This Ensuring that storage containers for both employees and contractors. issue has been studied and process equipment materials These practices and procedures thoroughly by researchers at the are compatible with the include: Oak Ridge National Laboratory, alkalinity of NaHS. Manu- as documented in Planning Controlling access and facturers of NaHS warn against Protective Action Decision-Making: supervising product delivery using copper, zinc, or aluminum. and transfer. Evacuate or Shelter-in-Place? Implementing an emergency (USDOE, 2002; Installing local exhaust notification system to inform http://www.osti.gov/bridge/). ventilation on process or storage emergency responders and A decision to evacuate should be equipment where personnel potentially impacted offsite based on the reasonable exposure is likely and ensuring residents of threatening assurance that movement is in that such systems are operating incidents. properly before starting a the best interest of those being process. Emergency evacuated: Evacuation: Downwind of a Installing fixed H2S monitors with alarms in NaHS storage Response release—before starting to and offloading areas where move upwind—unprotected concentrations could exceed safe Emergency responders must personnel should move levels. immediately take precautions in directly crosswind to one- the case of a fire or spill involving half of the downwind Providing PPE and emergency NaHS. If there is evidence of an distance from the spill. The eyewash and shower facilities H S release—either the presence of crosswind distance varies in where there is a risk of exposure 2 its characteristic rotten egg odor or relation to the size of the spill to NaHS. affirmative H2S monitoring and downwind distance. Ensuring that NaHS-containing results—emergency responders See Figure 5 and Table 4 for wastes are not flushed to acid- should: the initial isolation and containing sewers without protective action distances Restrict access to the spill/ controls to prevent a release of recommended by the DOT release site: Allow only H S. Emergency Response 2 emergency personnel equipped Guidebook (2004; Storing NaHS separately from with proper PPE to enter the area http://hazmat.dot.gov/ low pH (acidic) materials to (i.e., NIOSH-approved, full face- gydebook.htm). avoid inadvertent mixing. piece SCBA in pressure demand mode, and protective outer Clearly labeling NaHS con- garments). tainers, process piping, and critical process piping valves Decide whether to evacuate or that may contain NaHS with shelter-in-place: This decision essential hazard information. is made under urgent conditions. Factors that must be considered include population distribution, 10

Figure 5. Initial isolation and evacuation diagram.

Wind direction Table 4

H2S Initial Isolation Initial isolation 1/2 and Protective Action zone Downwind distance Distances

Downwind distance from spill Small Spill (a) 1. Isolate spill area 100 feet in all directions 1/2 Downwind 2. Protect persons downwind Spill/release distance Day (b) – 0.1 mile (528 feet) Night – 0.2 mile (1,056 feet)

Large Spill(c) 1. Isolate spill area 700 feet in all directions Shelter-in-place: This is a information regarding 2. Protect persons downwind precaution to keep people shelter-in-place is available Day (b) – 1.3 miles safe while remaining at http://www.cdc.gov/ (6,864 feet) indoors. It calls for taking and refuge in a preferably small, http://www.redcross.org/. Night – 3.9 miles (20,592 feet) interior room with no or few windows; closing windows Conduct continuous downwind (a) From a small package (55 gallons or smaller) or from a small leak from a and doors; turning off monitoring: Determine if H2S large package. heating and air-conditioning concentrations exceed the AIHA ERPGs18 (ERPG–3 or –2 values (b) Sunrise to sunset. systems; and listening to (c) From a large package or from many local TV/radio for emer- from Table 5) or the OSHA PEL; small packages. gency response directions. and continue to evacuate or shelter-in-place as required. Source: USDOT, 2004. Offsite residents or plant personnel who may be Firefighting required to shelter-in-place must be provided with Contact between NaHS and an instructions and training, acid—or exposure to excessive

and must have necessary heat—liberates H2S, which supplies on hand (e.g., food, presents an inhalation and fire water, tape, vinyl sheeting) prior to an incident. Detailed 18 NAS has developed acute exposure guideline levels that may be more protective than AIHA ERPGs. Interim

exposure levels for H2S are available at http://www.epa.gov/oppt/aegl/. 11

hazard. In addition, burning H2S Cool containers with

produces sulfur dioxide (SO2), flooding amounts of water which is a severe respiratory until well after the fire is irritant that can be life threatening. extinguished. If a fire involves NaHS, the DOT Withdraw immediately in Emergency Response Guidebook case of a rising sound from (2000) recommends the following:19 venting safety devices or Table 5 Small fires: discoloration of the tank. H2S Emergency Response Planning Guidelines Use dry chemicals, CO2, or ALWAYS stay away from water spray.20 burning tanks. 60-Minute Large fires: Concentration Spill Response (ppm) Use dry chemicals, CO2, In the event of a NaHS spill: ERPG–3 (a) 100 alcohol-resistant foam, or water spray. Do NOT allow NaHS to come in ERPG–2 (b) 30 Move containers of NaHS contact with acids. ERPG–1 (c) 0.1 from fire area if possible to Contain the spill. Do NOT flush do so without risk. to a sewer unless the sewer is (a) ERPG–3 is the maximum airborne designed and engineered to con- concentration below which it is believed Contain contaminated fire that nearly all individuals could be control water for later trol the H2S that may be released. exposed for up to 1 hour without experiencing or developing life- disposal. Remove sources of ignition so threatening health effects. Fires involving a tank, railcar, or that any H2S released will not (b) ERPG–2 is the maximum airborne ignite. concentration below which it is believed tank truck: that nearly all individuals could be exposed for up to 1 hour without Fight the fire from the Provide maximum ventilation. experiencing or developing irreversible maximum distance possible, or other serious health effects or Recover spilled material on symptoms that could impair their ability or use unmanned hose adsorbents, such as sand or to take protective action. holders or monitor nozzles. vermiculite, and place in covered (c) ERPG–1 is the maximum airborne concentration below which it is believed Do NOT allow water to enter containers for reclamation or that nearly all individuals could be containers of NaHS. disposal. exposed for up to 1 hour without experiencing other than mild transient For spills that exceed the 5,000- adverse health effects or perceiving a 21 clearly defined objectionable odor. pound reporting threshold,

Source: AIHA, 2004.

19 See Guide 154 for NaHS solutions. 20 Some manufacturers and fire safety professionals caution against using

extinguishers containing CO2 and dry

chemical extinguishing media because 21 NaHS is listed in Table 302.4 of the they form acids when mixed with water Superfund, Emergency Planning and and may exacerbate the generation of H2S Community Right-to-Know Act (40 CFR when used on fires involving NaHS. 302) as a hazardous substance with a They recommend using water in flooding reportable quantity of 5,000 pounds, quantities to fight the actual fire, and based on 100 percent purity (approxi- water spray or foam to control vapors. mately 1,077 gallons of 43 percent If CO2 or dry chemical extinguishers are solution). See http://www.epa.gov/ used, responders must wear proper swercepp/factsheets/epcra.pdf for more respiratory protection (i.e., SCBA). information. 12

notify NRC at 1-800-424-8802 or Emergency responders responsible Chemical shower and eyewash http://www.nrc.uscg.mil.22 for facilities that handle NaHS facilities must meet the require- should familiarize themselves with ments outlined in the OSHA Emergency Responders the ATSDR Medical Management Medical Services and First Aid Guidelines for H S (2003; Standard (29 CFR 1910.151(c)).25 Emergency responders must wear 2 http://www.atsdr.cdc.gov/ Applying elements of the NIOSH-approved, full face-piece MHMI/mmg114.html). Do NOT Emergency Eyewash and Shower SCBA in pressure-demand or enter an unknown or potentially Equipment Standard, ANSI Z358.1- positive-pressure mode and hazardous environment without 2004, fulfills OSHA requirements chemical-resistant outer garments ensuring that it is safe by sampling and provides adequate protection when there is a threat of airborne the air and/or wearing proper to workers.26 concentrations of H S exceeding 2 PPE.23 the PEL. To avoid endangering Skin Contact emergency responders, NaHS- or Inhalation of H2S H2S-contaminated outerwear Immediately remove contaminated should be discarded and victims Move the victim into fresh air and clothes and irrigate exposed skin decontaminated prior to placing administer oxygen as necessary.24 with copious amounts of water for

them in a confined space, such as a Victims of overexposure to H2S (or at least 15 minutes, regardless of medical transport vehicle. NaHS vapors that may contain symptoms. A physician may need

H2S) should immediately receive to examine the exposed area if Emergency rescue emergency medical attention. irritation or pain persists or worsens. Eye Contact If H S is present, do NOT 2 Ingestion attempt to rescue a fallen worker In the event of eye contact with without proper PPE. either NaHS or high concen- Do NOT induce vomiting or

trations of H2S, immediately attempt to neutralize ingested irrigate the eyes with copious NaHS. Immediately request First Aid amounts of water for at least 20 emergency medical assistance by minutes, or until the arrival of calling 911 and the national Poison Each year a large number of emergency medical personnel. An Control Center emergency hotline fatalities result from failed rescue ophthalmologic examination at 1-800-222-1222. attempts by those who rush into should be conducted as soon as dangerous environments to help possible because the extent of some fallen workers. First responders and injuries related to corrosive eye emergency medical personnel must exposure may not be apparent for protect themselves before rendering aid 48 to 72 hours. to others.

22 This is a regulatory threshold reporting quantity established by EPA with an emphasis on identifying adverse environ- 23 Eight contractor employees were 25 mental impact. Spills and releases of injured during the Georgia-Pacific http://www.osha.gov/pls/oshaweb/ much smaller quantities of NaHS can incident when they remained in the zone owadisp.show_document?p_ lead to catastrophic consequences. For of danger to assist with the rescue of table=STANDARDS&p_id=9806. example, the spillage of about 100 fallen workers. 26 ANSI Z358.1-2004 is available for gallons of NaHS led to the Georgia- 24 In some states, administering oxygen purchase at http://webstore.ansi.org/ Pacific incident, reviewed on page 13. requires emergency medical certification. ansidocstore/default.asp. 13

Whitehall Leather Company, Selected Case Whitehall, Michigan Studies (1 killed, 1 injured) On June 4, Georgia-Pacific, Naheola pulp 1999, the and paper mill, Pennington, driver of a Figure 6. Whitehall Leather offloading area. Alabama (2 killed, 8 injured) tanker truck NTSB filled with On January 16, 2002, two workers NaHS were killed and eight injured while inadvertently performing maintenance near a pumped the NaHS transfer terminal. NaHS tanker contents had recently been pumped from 15 into a storage tanker trucks into storage tanks. tank partially Because of a leaking pump, NaHS filled with accumulated in a spill containment “pickle acid” pit that was connected to the plant (hydrochloric acid sewer. acid). The When the containment pit was tanker truck drained, a relatively small quantity had arrived at of NaHS27 reacted with acid in the the plant sewer to produce H2S. The H2S during the leaked through a faulty manway night shift. cover seal into the area where the The shift supervisor—never having acid solution tanks were colocated contractors were working. received a shipment of NaHS and inside an earthen containment. The CSB investigation concluded believing it to be pickle acid— The reaction released an enormous that Georgia-Pacific management directed the driver to unload it into volume of H S, which caused 337 was unaware that the containment a pickle acid storage tank 2 people to seek medical evaluations pit drained to the acid sewer. (Figure 6). The resulting reaction and forced 2,000 downwind However, neither Georgia-Pacific released H S, which killed the 2 residents to evacuate. The nor the previous plant owners had driver and injured a plant evacuation lasted more than 30 adequately evaluated the potential employee. days as H S continued to evolve for hazardous chemical mixing in 2 from NaHS-saturated soil. the sewer system and the release of Powell Duffryn terminal fire, deadly amounts of H2S. Savannah, Georgia This incident illustrates the failure Consequently, plant personnel, (337 medical evaluations, of management systems to identify contract workers, and emergency community evacuation) and evaluate the hazards asso- responders were unaware of and ciated with colocating On April 10, 1995, the force from an unprepared for the dangers. incompatible materials inside a explosion in a solvent storage tank single spill containment. The EPA fractured NaHS transfer piping. investigation report (1998) is Up to 300,000 gallons of NaHS available at spilled and mixed with a similarly http://yosemite.epa.gov/opa/

large quantity of acidic cleaning 27 admpress.nsf/0/ CSB investigators estimated that 100 solution (Figure 7). The NaHS and gallons of NaHS was allowed to 8e314f057b62e118852565fe006fa986? accumulate in the pit. OpenDocument. 14

However, when the NaHS- containing pulping solution Figure 7. Powell Duffryn fire. EPA entered the sewer, it reacted with

waste acids and produced H2S— which escaped via drains, vents, and manways. The 10 injured employees were working at various locations near the vents and manways.

Horween Leather Company, Chicago, Illinois (8 killed, 43 injured)

On February 14, 1978, eight workers were killed, 43 were injured, and 57 sought medical evaluation after being over-

whelmed by H2S. The incident began when a substitute delivery Stone Savannah River pulp and Westvaco paper mill, driver unloaded a tanker truck of paper mill, Wentworth, Covington, Virginia NaHS into a storage tank Georgia (1 killed, 4 injured) (10 injured) containing an acid. He was On December 8, 1990, one worker On May 4, 1988, 10 employees were unfamiliar with plant operations was killed and four injured when a hospitalized for H S exposure and NaHS hazards, and was 2 unsupervised by plant personnel. large quantity of H2S formed when a 300,000-gallon storage tank during acid cleaning of a 20,000- containing pulping solution A large volume of H2S was gallon pulping solution pressure collapsed (Figure 8). The plant immediately generated, which led filter. H2S was routinely produced sewer system routinely controlled to evacuation of the entire plant inside the process vessel when the storm runoff, spills, and and surrounding community. cleaning solution was used to discharged wastes. Although the tank fill line coupling dissolve NaHS-containing pulping filtrate. Local exhaust ventilation normally controlled the H2S. Figure 8. WESTVACO paper mill tank failure.

However, on the day of this Crawford Akers Photography incident, H2S leaked from the system and accumulated inside the walled containment where workers were operating valves. According to witnesses, the workers imme- diately smelled H2S and tried to escape, but were overwhelmed before being able to climb out of the valve pit. 15 was designed to prevent inadver- References and CCPS, 1994. Guidelines for tent mixing, the driver created a Preventing Human Error in Process makeshift coupling when he was Additional Safety, AIChE. unable to attach the line from the truck. CCPS, 1992. Guidelines for Hazard Information Evaluation Procedures, AIChE. Prime Tanning Company, AIHA, 2004. ERPG/WEEL CCPS, 1989. Guidelines for Technical Berwick, Maine (6 killed) Handbook. Management of Chemical Process Safety, AIChE. On April 2, 1971, six workers died ANSI/ASSE, 2003. Safety when NaHS was inadvertently Requirements for Confined Spaces, Health and Safety Executive (HSE), pumped into a tank containing Z117.1–2003 2000. Designing and Operating acidic chrome tanning liquor, (http://webstore.ansi.org/ Safe Chemical Reaction Processes, which has a pH of 3 to 4. The ansidocstore/default.asp). Norwich, U.K.: HSE Books. NaHS delivery drivers had been McManus, Neil, 1999. Safety and instructed where to offload their ANSI/ASSE, 1998. Emergency Health in Confined Spaces, Lewis tanker truck. Eyewash and Shower Equipment, Z358.1-1998. Publishers/CRC Press. When the drivers discovered that NFPA, 1975. Hazardous Chemical the truck’s fill nozzle would not fit ANSI/ASSE, 1995. Safety Data, NFPA 49. the tank’s coupler, they used an Requirements for H2S Training adapter nozzle. There was no Criteria, Z390.1-1995. NIOSH, 2003. Recommendations for labeling on the tank to identify its ATSDR, 2003. Medical Management Chemical Protective Clothing, A contents or to warn of the potential Guidelines for Hydrogen Sulfide Companion to the NIOSH Pocket hazard. Approximately 160 Gas, August 2003 Guide to Chemical Hazards, Table gallons of NaHS had been (http://www.atsdr.cdc.gov/ H, August 2003 transferred to the tank before one of MHMI/mmg114.html). (http://www.cdc.gov/niosh/ the drivers noticed that workers npg/npg.html). inside the plant were collapsing. ATSDR, 1999. Toxicological Profile NLM Hazardous Substance Data NaHS had mixed with the chrome for Hydrogen Sulfide. Base (http://toxnet.nlm.nih.gov/ liquor to produce H S. 2 Bretherick, Leslie, P. G. Urben, and index.html). Martin J. Pitt, 1999. Bretherick’s Handbook of Reactive Chemical OSHA, 1993. Selected occupational Hazards, Sixth Edition, Vol. 1, fatalities related to pulp, paper Butterworth-Heinemann. and paperboard mills as found in OSHA fatality/catastrophe CCPS, 2003. Essential Practices for investigations, June 1993 Managing Chemical Reactive (http://www.osha.gov). Hazards, AIChE (http://www.aiche.org). Rekus, John F., 1994. Complete Confined Spaces Handbook, Lewis CCPS, 1996. Inherently Safer Publishers/CRC Press. Chemical Processes, A Life Cycle Approach, AIChE. 16

Sayers, Robert H., 1979. “Safety in USCSB, 2003. Investigation Report, USDOT, 2004. North American Handling and Using Sulfide, Hydrogen Sulfide Poisoning, Emergency Response Guidebook, Sulfhydrate, and Other Georgia-Pacific Naheola Mill, J. J. Keller and Associates Hazardous Chemicals in a Pennington, Alabama, January 16, (http://hazmat.dot.gov/ Tannery,” Journal of American 2002, Report No. 2002-01-I-AL, gydebook.htm). Leather Chemists Association, January 2003 USEPA, 1998. EPA Chemical Vol. 74, pp. 64–69. (http://www.csb.gov). Accident Investigation Report, Shih, Thomas, et al., 1967. USCSB, 2002. Hazard Investigation, Powell Duffryn Terminals, Inc., “Hydrogen Sulfide Vapor— Improving Reactive Hazard Savannah, Georgia, Office of Solid Liquid Equilibrium in Aqueous Management, Report No. 2001-01- Waste and Emergency Response, Systems as a Function of H, December 2002 EPA 550-R-98-003, May 1998 Temperature and pH,” TAPPI (http://yosemite.epa.gov/opa/ USDOE/Oak Ridge National Journal, Vol. 50, No. 12, pp. 630– admpress.nsf/0/ Laboratory, 2002. Planning 634, December 1967. 8e314f057b62e118852565fe006fa986? Protective Action Decision-Making: OpenDocument). The Innovation Group, 2003. Evacuate or Shelter-in-Place? Chemical Profiles ORNL/TM-2002-144, prepared (http://www.the-innovation- for Federal Emergency group.com). Management Agency (http://www.otsi.gov/bridge/). USCG, 2001. Chemical Hazards Response Information System (CHRIS; http://www.chrismanual.com).

The U.S. Chemical Safety and Hazard Investigation Board (CSB) is an independent Federal agency whose mission is to ensure the safety of workers, the public, and the environment by investigating and preventing chemical incidents. CSB is a scientific investigative organization; it is not an enforcement or regulatory body. Established by the Clean Air Act Amendments of 1990, CSB is responsible for determining the root and contributing causes of accidents, issuing safety recommendations, studying chemical safety issues, and evaluating the effectiveness of other government agencies involved in chemical safety. No part of the conclusions, findings, or recommendations of CSB relating to any chemical incident may be admitted as evidence or used in any action or suit for damages arising out of any matter mentioned in an investigation report (see 42 U.S.C. § 7412(r)(6)(G)). CSB makes public its actions and decisions through investigation reports, summary reports, safety bulletins, safety recommendations, case studies, incident digests, special technical publications, and statistical reviews. More information about CSB may be found at http://www.csb.gov. CSB publications may be downloaded at CSB investigation reports may be purchased from: http://www.csb.gov or obtained by contacting: National Technical Information Service U.S. Chemical Safety and Hazard Investigation Board 5285 Port Royal Road Office of Congressional, Public, and Board Affairs Springfield, VA 22161-0001 2175 K Street NW, Suite 400 (800) 553-NTIS or (703) 487-4600 Washington, DC 20037-1848 Email: [email protected] (202) 261-7600 For international orders, see: http://www.ntis.gov/support/cooperat.htm.