John's Thesis

UNIVERSITY OF CINCINNATI

Date: March 1, 2004

I, John Robert Moore III______, hereby submit this work as part of the requirements for the degree of:

MASTER OF SCIENCE______in:

Environmental and Industrial Hygiene______

It is entitled: A Study of the Breakthrough Times of 1-Bromopropane and______2-Bromopropane in Select Gloves______

This work and its defense approved by:

Chair: Dr. Glenn Talaska Dr. G.E. Burroughs Dr. Paul Succop Dr. Christopher Reh

A Study of Breakthrough Times of 1-Bromopropane and 2-Bromopropane in Select Gloves

A Thesis submitted to the

Division of Research and Advance Studies

of the University of Cincinnati

in partial fulfillment of the

requirements for the degree of

MASTER OF SCIENCE

in the Department of Environmental Health

of the College of Medicine

2004

John R. Moore III

B.S., Saint Augustine’s College, 1996

Committee Chair: Dr. Glenn Talaska ABSTRACT

The focus of this study is to determine breakthrough times of 1-bromopropane (1-

BP) and 2-bromopropane (2-BP) in industrial glove materials used by industry. At this time, limited toxicological data is available on health effects of dermal exposure to 1-BP and 2-BP. However, adverse health effects have been shown in other studies of animals and humans. Three types of gloves were selected for this study and tested against the two

chemicals using the American Society of Testing Methods (ASTM) -739 method. Two

detection methods, a real-time monitor and a gas chromatograph were used in the

evaluations to detect breakthrough times in the gloves. Physical changes in the gloves

after testing were documented.

At the conclusion of the study, Silver Shield® was the best barrier against the two chemicals, since no breakthrough occurred. Chemical breakthrough occurred in nitrile glove after a period of 30 - 44 minutes. In the third glove, polyvinyl chloride (PVC) breakthrough occurred within 3 – 7 minutes against the two chemicals, so it is not recommended for use. The two chemicals had similar chemical characteristics and no significant difference was found in the overall breakthrough detection times. Significant differences in the mean breakthrough time of different gloves of different materials were found. The two detection methods differed in sensitivity but 1-BP and 2-BP did not show significant differences in breakthrough time.

I wish to dedicate this thesis to my family, especially my parents, John and Clara

Moore, for their love and encouragement. They truly share in this accomplishment.

John R. Moore III

ACKNOWLEDGEMENTS

I wish to express sincere thanks to my advisor, Dr. Glenn Talaska, for his guidance, patience, and professional expertise. I would also like to thank my committee:

Dr. Ed Burroughs for his technical knowledge and inspiration in this entire process; Dr.

Paul Succop for his skills and insight; and Dr. Chris Reh for his technical expertise and invaluable information on this subject.

I would also like to thank Charles and Barbara Corsheen/Powell for selecting me as the first recipient of the Corsheen/Powell Fellowship. It is an honor and privilege to be associated with them.

Also, thanks to all of my friends and family that kept asking, “Are you finished yet?”, now I can answer “Yes, I’m done”.

Most of all I want to thank God without whom none of this would be possible.

He is my saviour, provider and guides me throughout my life.

TABLE OF CONTENTS

LIST OF TABLES...... 2 LIST OF FIGURES ...... 3 LIST OF GRAPHS ...... 4 LIST OF ABBREVIATIONS...... 5 INTRODUCTION ...... 7 1.1 Challenge Chemicals ...... 7 1.1.1 1-Bromopropane (1-BP) ...... 7 1.1.2 2-Bromopropane (2-BP) ...... 8 1.2 Animal Exposure Studies...... 10 1.3 Human Exposure Studies...... 13 1.4 Standards...... 15 1.4.1 Environmental Protection Agency (EPA)...... 15 1.4.2 Occupational Safety and Health Administration (OSHA)...... 16 1.5 Glove Materials...... 18 1.5.1 Scenarios and Applicable Hazards...... 18 1.5.2 Background of Making Gloves...... 20 1.6 Selected Gloves Manufacturing Techniques ...... 22 1.6.1 Nitrile Gloves ...... 22 1.6.2 PVC Gloves ...... 23 1.6.3 Silver Shield® ...... 24 2 HYPOTHESIS ...... 26 3 MATERIALS AND METHODS...... 27 3.1 Materials ...... 27 3.1.1 Gas Chromatograph (GC)...... 29 3.1.2 Real-time Monitor (RTM) ...... 32 3.2 Breakthrough Testing with ASTM Method...... 32 3.3 Test Procedure ...... 34 3.4 Sampling Regimen...... 36 4 RESULTS ...... 37 4.1 Results Summary ...... 50 5 DISCUSSION...... 51 6 CONCLUSION...... 56 7 REFERENCES ...... 58

LIST OF TABLES

Table 1. Chemical and Physical Properties……………………………………………...9 Table 2. Glove Chart….…………………………………………………………………25 Table 3. Summary Chart of Breakthrough Time………………………………………..38 Table 4. 1-BP and 2-BP Comparisons of Breakthrough Time………………………….39 Table 5. Glove Comparison of Breakthrough Time…………………………………….40 Table 6. GC and RTM Comparisons of Breakthrough Time…………………………...41

LIST OF FIGURES

Figure 1. Mass spectra of 1-bromopropane…………………………………………..28 Figure 2. Test Cell …….……………………………………………………………..31

LIST OF GRAPHS

Graph 1. PVC vs. 1-Bromopropane Breakthrough Time….……………………………42 Graph 2. PVC vs. 2-Bromopropane Breakthrough Time...... 43 Graph 3. PVC vs. Bromopropane Breakthrough Time Standard Error…………………44 Graph 4. Nitrile vs. 1-Bromopropane Breakthrough Time..……………………………45 Graph 5. Nitrile vs. 2-Bromopropane Breakthrough Time..……………………………46 Graph 6. Nitrile vs. Bromopropane Breakthrough Time Standard Error.………………47 Graph 7. Comparison of Detection Methods Breakthrough Time 1-Bromopropane...... 48 Graph 8. Comparison of Detection Methods Breakthrough Time 2-Bromopropane…..49

LIST OF ABBREVIATIONS

1-BP 1-Bromopropane 2-BP 2-Bromopropane ANOVA analysis of variance ANPRA Advance Notice Propose Rulemaking Agency ASTM American Society for Testing and Materials Ave average BSOC Brominated Solvents Consortium C Celsius C2 second carbon C3 third carbon CAA Clean Air Act CAS RN Chemical Abstract Service Registry Number CERHR Center for Evaluation of Risk to Human Reproduction CFC Chlorofluorocarbon CNS central nervous system CFR Code of Federal Regulations CL confidence limit Diff difference EPA Environmental Protection Agency eV electronic volts g gram GC gas chromatography GLP Good Laboratory Practices IP ionization potential KISCO Korea Industrial Safety Corporation Kg kilogram Kow octanol-water partition coefficient L liter LC50 lethal concentration, 50% mortality LC100 lethal concentration, 100% mortality Mins minutes mm Hg millimeters mercury MSDS Material Safety Data Sheet MW molecular weight N number NIEHS National Institute of Environmental Health Sciences NIOSH National Institute of Occupational Safety and Health NTP National Toxicology Program OSHA Occupational Safety and Health Administration PEL Permissible Exposure Limit PPE personal protective equipment ppb parts per billion ppm parts per million

RTM real-time monitor Std. Dev. standard deviation Std. Error standard error sq. cm square centimeter SNAP Significant New Alternatives Program TWA time weighted average UV ultra violet

INTRODUCTION

1.1 Challenge Chemicals

1-bromopropane (1-BP) and 2-bromopropane (2-BP) are related solvents that were

selected due to the lack of dermal exposure information at the time of the testing1. These

chemicals were deemed pure at concentrations of 90 – 100% grade reagents.

1.1.1 1-Bromopropane (1-BP)

There are two methods used to produce 1-BP. 1-BP can be made by reacting 1-

propanol with hydrogen bromide, then removing the water to form 1-BP2, 3. 1-BP can

also be created by dehydrating 1-propanol with bromine or hydrogen bromide in the

presence of a sulfur catalyst4, 5. 1-BP is currently used in spray adhesives, precision

cleaning, and as a degreaser6, 7. It has also been used as a solvent for fats, and waxes, and

as an intermediate for synthesis of pharmaceuticals, insecticides, flavors, or fragrances2.

Manufacturers of 1-BP, who are also part of the Brominated Solvents Consortium

(BSOC), are the Albemarle Corporation, Dead Sea Bromine Group/ AmeriBrom,

ATOFINA, and Great Lakes Chemical Corporation. Some of the solvents that contain 1-

BP are Hypersolve, Abzol, Lenium, Contact Cleaner- NBP Heavy Duty, Leksol, Ensolv,

Solvon, Vapor Edge 1100, X-Cel, VDS-3000, CobarClean NPB, No Flash Nu Cleaner,

Heavy Duty Degreaser II, and 1640 Bulk. It is estimated that approximately 10.6 million

pounds of 1-BP was either sold or emitted globally between 1999 and 20002, 8.

There is no information documenting the presence of 1-BP in ambient air, water,

food or consumer products9. The atmospheric lifetime of 1-BP is reported to be less tan

20 days10.

1.1.2 2-Bromopropane (2-BP)

2-BP is made by heating isopropyl alcohol with hydrogen bromide11. 2-BP is used as an intermediate in the synthesis of pharmaceuticals, dyes, and other organics. In

Asia, 2-BP has been used as a replacement for some ozone depleting products11. No data was found on the estimated amount of 2-BP used by the consumer or general population.

There is no information documenting the presence of 2-BP in ambient air, water, food or consumer products12.

Chemical and Physical Properties2, 12 Property 1-Bromopropane (1- 2-Bromopropane (2- BP) BP) Other names N-Propyl Bromide; Isopropyl Bromide Propyl Bromide Molecular formula C3H7Br C3H7Br Molecular weight 123 123 Appearance Clear to yellow liquid Clear to yellow liquid Odor Strong odor Odor of halogenated solvents Chemical family Alkyl bromide Alkyl bromide CAS RN 106-94-5 75-26-3 Boiling Point 71°C at 760 mm Hg 59.38°C at 760 mm Hg Melting Point -110°C -89°C Specific Gravity 1.353 at 20°C 1.31 at 20°C Solubility in Water 2,450 mg/L at 20°C 3,180 mg/L at 20°C Vapor Pressure 110.8 mm Hg at 20°C 216.47 mm Hg at 25°C Stability Stable Stable with normal use and storage Reactivity Reacts with strong Incompatible with oxidizing agents and oxidizing agents bases Log Kow 2.10 2.14 Flammability Flammable No flammability known Flash Point 25.6°C 19°C (closed cup) *the columns highlighted in gray point out significant differences noted by the author

Table1

1.2 Animal Exposure Studies

Limited animal and human studies have been conducted to assess the health

effects of 1-BP and 2-BP2, 12. The National Toxicology Program (NTP), the National

Institute of Environmental Health Sciences (NIEHS), and the Center for the Evaluation of

Risks to Human Reproduction (CERHR) have published comprehensive studies of 1-BP

and 2-BP in which a panel of experts reviewed the available toxicity testing data and

gave opinions of the test data13. Overall the panel recommended that additional studies of 1-BP and 2-BP be conducted to better characterize acute and, chronic effects related to exposure2, 12.

1-BP was found to have developmental, reproductive, and hematopoietic system

toxicity in rats14, 15, 16. However, available human data is inconclusive on the potential

for reproductive or developmental toxicity of 1-BP. The rat data was found to provide

sufficient exposure concentrations from animal studies and are being compared to human

exposure concentrations to ascertain levels of concern for 1-BP17. Animal studies have

shown that 1-BP can be absorbed into the blood stream from inhalation exposure, and

absorbed through the skin18, 19, 20. A Japanese and U.S. animal study identified that 1-BP

16 was a reproductive toxin . Oral (lethal dose) LD50 in rats is reported to be 4 g/kg. The

inhalation (lethal concentration) LC50 in rats is reported to be 50,394 parts per million

(ppm) for 30 minutes and 6,972 ppm for 4 hours of exposure to 1-BP21.

Elf Autochem19 conducted a dermal toxicity study of 1-BP. In the study, rats

were shaved and wrapped with a gauze pad (semi-occlusive wrap) for 24 hours. There

was no evidence of dermal irritation, gross lesions at necropsy, or clinical signs of

toxicity. If the rats had been wrapped in an occlusive wrap or if the wraps were changed

during the test and if the time of the test were extended, results may have been different.

This may have allowed for a longer exposure period.

Barber et al.13 examined the mutagenicity of 1-BP in Salmonella strains TA1535,

TA1537, TA1538, and TA100 with and without metabolic activation. Positive results

were only obtained from TA1535 and TA100 without metabolic activation, which

indicated an increased mutation frequency after 1-BP treatment. The level of dermal

exposure that should be of concern when using 1-BP remains unclear.

2-BP has specific reproductive and hematopoietic toxicity in both sexes in

humans and experimental animals; it can impair the functions of the testes23, especially spermatogonia in males; it can impair ovarian functionError! Bookmark not defined., resulting in a disturbed estrous cycle and loss of ocytes in females; it can impair bone marrow22, resulting in pancytopenia; and it has weak potent mutagenicity in bacterial

mutation assays. One investigation suggest that an occupational exposure of 10 ppm or

less may be an acceptable limit for 2-BP11. At this time there is no occupational exposure

limit for 2-BP. 2-BP has not been used in the workplace at that high of a concentration

(<90%) since February 199622, 11.

Sufficient evidence has been provided to support that exposure to 2-BP cause

reproductive toxicity in males and females, but the routes of exposure have not been

determined. Ichihara et al.23 conducted a study on male rats in order to examine and

explain the reproductive and hematopoietic toxicity of 2-BP. His findings showed that 2-

BP has a specific toxicity on the testes of male rats. He also examined peripheral blood

and bone marrow in rats and found that 2-BP has peculiar hematopoetic toxicity in male rats.

Kim et al. 24 conducted an animal study to clarify 2-BP ovarian toxicity in the virgin female rat. The results of his study confirmed that 2-BP has ovarian toxicity in rats. The LC50 of 2-BP was found to be 31,171 ppm.

There is no information available on the skin penetration of 2-BP. However, bromine chemicals such as methyl bromide, ethyl bromide, and ethylene dibromide have all been noted as having skin occupational exposure limits by the American Conference of Government Industrial Hygienist, 1991 (ACGIH). Occupational poisoning cases in association with methyl bromide skin penetration were also reported [Jordi 1953;

Longley and Jones 1965]. This information suggests that biological monitoring may be an effective way of assessing potential skin penetration of 2-BP. Urinalysis for acetone and bromide ions in combination may be useful for biological monitoring of occupational exposure to 2-BP.

Limited animal studies show that 2-BP may be more toxic than 1-BP on reproductive and hematopoietic endpoints. Yu et al.25, 8 reported that in rats 1-BP was a more potent nervous system toxicant, but a less reproductive and hematopoietic system toxicant than 2-BP.

Ichihara et al.26 conducted a study to examine the dose and duration neurotoxicity response to 1-BP exposure using rats exposed to 1-BP vapors for 8 hours/12 weeks.

Adverse changes to the nervous system were noted, and in comparing the study to a similar study using 2-BP, the authors concluded that 1-BP is a more potent neurotoxicant than 2-BP.

Barnsley et al.27 studied the metabolism of 1-BP and 2-BP by radiochromatographic examination of urine excreted by rats that had been fed S-labeled yeast and then injected subcutaneously with these compounds. 1-BP was converted into n-propylmercpturic acid sulphoxide, n-propylmercpturic acid, and 2- hydroxypropylmercapturic acid. 2-BP only showed trace amounts of those same metabolites. These differences in the substrate disappearance and rate of propyl alcohols from bromopropanes suggest that there may metabolic pathways other than the pathway from bromopropane to propyl alcohols or they may be further metabolized in the incubation system. Matsushma28 reported that 2-BP was more mutagenic in the gas exposure method than in the preincubation method.

There are no data available to evaluate the sensitivity of populations based on gender, age, or genotype of exposure to 1-BP and 2-BP. There are no available data on the potential carcinogenicity of 1-BP and 2-BP in humans or animals. There are no case reports or epidemiological data to assess potential developmental toxicity in humans induced by exposure to 1-BP. The data are sufficient to indicate the inhalation exposure to 1-BP can induce signs of developmental toxicity29. No information concerning the toxicokinetics of 1-BP and 2-BP in humans was found. However, evidence from animal data exists that indicates 1-BP can be absorbed into the systemic circulation from inhalation exposure2.

1.3 Human Exposure Studies

In July 1995, the Korea Industrial Safety Corporation (KISCO) investigated a

Korean factory after it was reported that some of the workers were experiencing adverse health affects that could be caused by their work activities11. According to the

investigation 8 men and 25 women were exposed to solvents containing 95.5% of 2-BP.

It was noted that 2-BP was very volatile and permeable to the skin. Interviews conducted

during the study showed that no one used any personal protective equipment such as

gloves or respirators during their 12-hour shifts. It was concluded that 2-BP was the

cause for the reproductive and hematopoietic disorders found in the workers in the plant.

Sclar30 published a case report of a male who experienced weakness in his lower

extremities, numbness, and difficulty swallowing and urinating after a 2 month

occupational exposure to a degreasing and cleaning solvent that contained 95.5% 1-BP.

The report did not quantify exposure and did not specify which route(s) of exposure

occurred. According to Sclar evidence in the study suggested that the patient was

suffering from a symmetric demyelinating polyneuropathy with central nervous system

(CNS) involvement. These were similar symptoms observed in rats exposed to 1-BP,

Sclar hypothesized that the patient’s symptoms may have resulted from exposure to 1-

BP. Levels of exposure were not measured. The patient did wear gloves (type of glove

unspecified); however, the skin on his right hand was darkened, which suggest that the

gloves may not have offered adequate protection.

Some workplace monitoring data for a 8-hour time weighted average (TWA) have

been conducted for 1-BP used in adhesive spray and metal cleaning applications under

usual working conditions31, 32. The National Institute of Occupational Health (NIOSH) conducted 8-hour TWA, collecting personal air samples in 3 plants where 1-BP was used6. Exposures ranged from 18 to 381 ppm in spray adhesive operations.

No exposure studies have been conducted to characterize dermal health effects in

humans at this time. Because 1-BP is volatile it may be difficult to measure human

dermal exposure and absorption because it could evaporate before an assessment would be conducted. Biological monitoring may be the best method to assess dermal exposure in humans.

1.4 Standards

1.4.1 Environmental Protection Agency (EPA)

On June 3, 2003, the Environmental Protection Agency (EPA) approved the addition of 1-BP to the list of acceptable products, subject to use as alternatives for class I and class II ozone depleting substances in the solvent applications. The EPA established the Significant New Alternatives Policy (SNAP) program to identify substitutes for ozone-depleting compounds that offer lower overall risks to human health and the environment. SNAP implemented section 612 of the amended Clean Air Act (CAA) of

1990 that requires the EPA to evaluate substitutes for ozone-depleting compounds33. The intent of the requirement is to move away from using ozone-depleting compounds while avoiding use of substitutes that pose other serious environmental or health problems to the public34.

The EPA felt that 1-BP posed less risk to the stratospheric ozone layer because it had a shorter atmospheric lifetime and low ozone depletion potential. The EPA responded favorably in accepting 1-BP as a substitute for ozone depleting products primarily because it breaks down in the atmosphere within 21 days and it less flammable than other chemicals in its class. After reviewing toxicology studies the EPA moved forward on approving 1-BP for use in the United States as a substitute for ozone- depleting compounds. The Advance Notice of Proposed Rulemaking Agency (ANPRA) was primarily concerned about 1-BP in products and processes. The EPA collected

information as part of the ANPRA, and proposed the acceptability of 1-BP as a substitute for class I and class II ozone depleting substances.

Research has shown concentrations of 2-BP exist in 1-BP1. The EPA has established maximum concentration limits for 2-BP in applications involving 1-BP. The

EPA requires that 1-BP not contain more than 0.05% of 2-BP by weight before adding stabilizers or other chemicals. Due to the nature and similarities of 2-BP we chose to include both chemicals in this study. If 2-BP is to be used in the future as a substitute for ozone-depleting compounds by U.S. industry it will be required to undergo the same

SNAP evaluation that 1-BP went through to gain approval.

The EPA recommends that worker exposure not exceed the level of 25 ppm over an 8-hour TWA. This limit is designed to protect workers until the Occupational Safety and Health Administration (OSHA) sets its own standards33. The EPA also recommends that workers avoid skin exposure to 1-BP by using protective clothing and laminated gloves (i.e. Silver Shield®). Even though the EPA does not have the enforcement powers of OSHA, recommended exposure limits are usually compiled with if set by a regulator agency such as the EPA. OSHA and NIOSH have both nominated 1-

BP and 2-BP for reproductive toxicity and carcinogenicity testing1.

1.4.2 Occupational Safety and Health Administration (OSHA)

OSHA does not have a permissible exposure limit (PEL) for 1-BP and 2-BP, however, they have set forth regulations for gloves used in industry. The Code of Federal

Regulations (CFR) 29 of the General Industry Standard 1910.138, specify the use of hand protection in the workplace when necessary35. A practical way to assess hand protection is by acquiring knowledge of breakthrough times in selected gloves for specific

chemicals and products. With so many products being produced, some manufacturers

may only use generic hand protection recommendations such as “wear gloves while

working with this product”35. This standard does not offer detailed information in guidance of types of gloves to be worn with hazardous products or chemicals.

Sometimes personal protective equipment data may not exist on a particular chemical or product. This may be an issue if a variety of materials are not tested against specific chemicals and products. In 1910.138(a) OSHA states that “employers shall select and require employees to use appropriate hand protection when employees' hands are exposed to hazards such as those from skin absorption of harmful substances; severe cuts or lacerations; severe abrasions; punctures; chemical burns; thermal burns; and harmful temperature extremes.” OSHA also states that “employers are to select gloves based on applicable characterizations …base the selection of the appropriate hand protection on an evaluation of the performance characteristics of the hand protection relative to the task(s) to be performed, conditions present, duration of use, and the hazards and potential hazards identified.” Under certain circumstances it may be feasible for an employer to institute a glove testing procedure to accurately assess hand protection in specific workplaces and operations.

1.5 Glove Materials

1.5.1 Scenarios and Applicable Hazards

There are a variety of glove types on the market today designed for use with specific chemicals and chemical families. Each glove type has its own advantages and disadvantages that should be considered carefully before use. Events in the scientific community have illustrated the need for the use of proper protective gloves while working with hazardous chemicals. Serious injury and even death may occur if some chemicals are able to permeate or degrade the glove lining.

Such was the case with Karen E. Watterhahn, Ph.D., professor of chemistry at

Dartmouth College, who died on June 8, 1996 at age 4836. Testing of the type of gloves worn by the professor supports the hypothesis that dimethylmercury rapidly penetrated her gloves causing transdermal exposure. Before Dr. Watterhahn’s death, she recounted one incident in which she spilled drops of dimethylmecury (estimated to total 0.1 to 0.5 ml) on disposable latex gloves during a transfer procedure in a fume hood while preparing a mercury nuclear magnetic resonance (Hg NMR) standard. Breakthrough times and permeation tests done by an independent testing laboratory found that dimethylmercury penetrates disposable latex gloves instantly.

In retrospect, a highly resistant laminate glove (Silver Shield®) would have offered protection for up to 480 minutes37. This tragic situation serves as a reminder of the false sense of protection that one may feel by wearing the improper protection. One way to account for data to aid in the selection of proper gloves in this and many other

situations is by knowing the breakthrough time for gloves against the chemical or product

that is used.

Gloves made from polymers and other materials have certain weaknesses in terms

of preventing resistance and physical properties like resistance to tearing and abrasion.

Several factors that influence glove selections are: the type of chemicals to be handled or

used; frequency and duration of chemical contact; nature of contact (total immersion or

splash only); concentration of chemicals; temperature of chemicals; abrasion/resistance

requirements; puncture-, snag-, tear-, and cut-resistance requirements; length to be

protected (hand only, forearm, arm); dexterity requirements; grip requirements (dry grip,

wet grip, oily); thermal protection (for example, when handling anhydrous ammonia);

size and comfort requirements; and price.

For a given thickness, the type of polymer selected has the greatest influence on

the level of chemical protection38. The manufacturing process of glove making may result in slight variations in performance. The user should exercise care and check the glove regularly for physical degradation and diminished physical performance39.

It is extremely important to avoid secondary exposure to the chemical after

application. Some solvents are very difficult to remove from the glove material. Once

absorbed, some chemicals will continue to diffuse through the material after the surface

has been decontaminated. For highly resistant chemical gloves, the amount of

contamination of the interior glove may be insignificant. But for moderately performing

gloves, significant amounts of chemicals may contaminate the interior of the glove. In

addition to the chemical resistance of the glove material, the amount of chemical that

reaches the surface can be affected by the duration of exposure, duration of storage, the surface area exposed, and temperature.

1.5.2 Background of Making Gloves

The following ingredients are needed to make a glove; latex, water, vulcanizing agents, accelerators, activators, blockers, retarders, anti-oxidants, preservatives, odorants, colorants, stabilizers, and processing aids. Different gloves will have different chemicals in differing concentrations in the final product. There are some slight variations in the protein content from one lot to the next. Usually the variations are minimal and do not affect the performance of the glove.

Most chemical resistant gloves are made with different rubbers: natural, butyl, chloroprene, nitrile, and fluorocarbon (Viton); or various plastics: polyvinyl chloride

(PVC), polyvinyl alcohol, and polyethylene. These materials can be blended or laminated together for better performance, such as Silver Shield® and 4H® which have good chemical resistance and are barrier laminates.

Until the year 1910, the word “rubber” would describe most gloves40. When use of synthetic materials began to emerge, especially those synthetics that had capabilities different from natural rubber, more descriptive terminology was used to describe the materials. Vulcanized rubber is stronger and more elastic than ordinary rubber. The sulfur cross-links the polymer chains in the latex; it can be stretched, but the polymer chains snaps back so the product returns to its original shape. Natural latex is a polymer because it is a long molecule composed of many repeating smaller molecular units. The basic unit of the polymer is isoprene (synthetic rubbers use different chemicals as the basis for creating the polymer). H.L. Fisher started to use the term “elastomer” to

embrace natural as well as synthetic products with those properties generally associated

with natural rubber40.

Elastomers are types of rubber that include: natural rubber, polybutadiene, polyisobutylene, and polyurethane. Elastomers can be stretched beyond their original length, and return to its original shape without permanent deformation. Accelerators are chemicals that speed the cross-linking process, either by donating sulfur atoms or by binding with sulfur. Most of the world’s synthetic rubber is made from styrene and butadiene, which are found in petroleum. A second group of chemical sensitizers is the anti-oxidants, which are added to decrease the rate of rubber degradation.

Latex is a general term for a material that will not dissolve suspended in water as fine droplets. Latex is a natural product made from rubber trees that produce a milky, viscous liquid. The bark of the rubber tree is shaved so that the liquid bleeds, and it is then collected. Unless treated with chemicals soon after collection, the latex tends to harden into a gum. Latexes are often modified and used in the forming of coating and dipped goods. Both natural and synthetic elastomers are essentially useless in their raw state. To make strong vulacanizates, the raw gum must be compounded with several ingredients39. The term “pigment” refers to any solid mixed into a raw elastomer with the

exception of those used as vulcanizing agents40. Dry pigments are loosely classified as

reinforcing agents, or fillers. The pigmentation improves the properties of the

vulcanizators.

There are two primary methods of manufacturing liquidproof gloves: 1) latex

dipping, and 2) cement dipping40. Individual glove manufacturers may modify these

techniques in order to gain various processing advantages. The exact details of liquidproofing are often under patent protection.

1.6 Selected Gloves Manufacturing Techniques

1.6.1 Nitrile Gloves 41

Latex dipping is used to produce the nitrile gloves.

1. The latex dipping processes starts with natural or synthetic rubber latexes that are

already made.

2. Small particles of elastomers are suspended in water in a coagulant tank.

3. A porcelain hand form is dipped into a coagulant tank, which may contain

calcium nitrate, water, alcohol or a mixture of the three. This is a single dip

operation and the desired thickness is determined by the length of time the hand

form is left in the latex tank. The coagulant causes the elastomer particles to

separate from the water and attach themselves onto the hand form.

4. The solvent then evaporates.

5. The porcelain hand is then dipped into tank of nitrile latex. This tank contains

butadiene, nitrile, rubber, zinc oxide, and other accelerators depending on the type

of glove being formed.

6. The gloves are then dipped into warm water to rinse off salt and flush out any

other unwanted materials.

7. The gloves mold is put in an oven to dry for approximately one hour.

8. Then it is put in another oven for curing process at a temperature no more than

300 degrees Fahrenheit for approximately one hour.

9. The gloves then harden on the mold- it is formed with what will ultimately be the

inside of the glove on the outside of the mold. The uniformity of the coating is

dependent on the concentrations of the latex and coagulant.

10. The gloves then go through one or more rinses to leach out protein and residual

chemical.

11. Finally, the finished product is stripped off the mold, packaged, and sterilized.

1.6.2 PVC Gloves 41

PVC gloves are made using the latex dipping technique in this process.

1. A smooth porcelain hand mold is dipped into a coagulant tank, which contains

vinyl latex and plasticatizers. This is a single dip operation and the desired

thickness is determined by the length of time the hand form is left in the latex

tank.

2. Solvents are then added to change the elastomer from a solid to a liquid.

Stabilizers and viscosity adjust to keep the gloves flexible.

3. The gloves are then oven dried for approximately 15 minutes.

4. The gloves then go through a fusing process as the water is eliminated and the

PVC particles fuse together in an oven similar to the curing process in making

nitrile gloves.

5. Then the gloves are treated for anti-stick so that they don’t fuse together. This is

either done by using a powdering process using cornstarch or spraying with

chlorine bleach.

6. The gloves are then dried, packaged, and shipped.

1.6.3 Silver Shield® 37

The Silver Shield® gloves used in this study are made by this one-step process.

1. The film used is already laminated from a plastics film manufacturer which

contains polyvinyl alcohol/acetate copolymer as the middle layer. This material is

patented. Two sheets of this film are piled on top of each other and fed into a

sealing press.

2. A die, shaped like the edge of a flattened hand, clamps down on these two sheets

and simultaneously seals them together and cuts the resulting glove away from the

rest of the film.

3. The gloves are then packaged, and shipped.

Glove Chart

Glove Material Advantages Disadvantage

Nitrile Are fairly inexpensive and have a wide range of uses. These Have poor chemical barrier from gloves are very popular, and are commonly used in a variety of benzene, methylene chloride, industries. The most common application for nitrile gloves is trichloroethylene, and many ketones. chemical handling and processing. Nitrile gloves, also known as acrylonitrile-butadiene, can offer a higher degree of puncture- resistance and dexterity than other chemical gloves. Material does not weaken or swell in aromatics, caustics, petroleum solvents, or animal fats. Protects against oils, greases, aliphatic chemicals, xylene, and trichloroethane. PVC Are moderately priced and have been identified as having good The same plasticizers that allow for chemical resistance to aqueous chemicals. Offer excellent many physical properties can be physical properties. They can be used for medium chemical "chemically stripped" from the glove protection against strong acids and bases, inorganic salt material. PVC offers poor chemical solutions, alcohol, and water based solutions. protection from petroleum solvents. Use in petroleum solvents may cause the glove to stiffen and crack. Silver Shied® Are made from Norfoil, resists permeation and breakthrough by Poor fit and grip. Material does not more toxic / hazardous chemicals than any other type of glove flex well and has little puncture on the market today. Can be used as an inner liner under other resistance. Expensive. gloves, but is strong enough to be used alone. It is a lightweight, flexible laminate that has been engineered to provide a high degree of permeation resistance from a wide range of solvents, chemicals, acids, or bases. Frequently used in hazardous material situations or when handling unknowns.

Table 2

2 HYPOTHESIS

The Hypothesis of this study is that Silver Shield gloves will not have a breakthrough while being tested against 1-BP and 2-BP; while the PVC gloves and nitrile gloves will have breakthrough against 1-BP and 2-BP.

3 MATERIALS AND METHODS

3.1 Materials

Chemicals

All chemicals were deemed chemically “pure” based on the 90 - 100% rating listed on

the product label and MSDS.

1. 1-BP (J.T. Baker, 222 Red School Ln., Phillipsburg, NJ 08865)

2. 2-BP (ATOFINA Chemicals, Inc., 2000 Market St., Philadelphia, PA 19103)

Gloves

The three glove materials selected were:

1. Unsupported nitrile, (Ansell Occupational Healthcare

1300 Walnut St Coshocton, OH 43812)

2. Polyvinyl Chloride (PVC), (Ansell Occupational Healthcare

1300 Walnut St Coshocton, OH 43812)

3. Silver Shield®, (North Safety Products, 2000 Plainfield Pk. Cranston, RI 02921)

ASTM Test Cells

Two ASTM Test cells (Pesce Lab Sales, P.O. Box 235, Kennett Square, PA 19348) were utilized for each permeation test (see figure 1 for a drawing of the Test Cell). Each glove material was positioned vertically between glass chambers, which were sealed with

Teflon gaskets, and secured with stainless steel flanges. The exposed surface area of the glove material was held in place by constraints of the gaskets at 19.63 cm2.

Figure 1

Calibration Standard

The calibration standards that were used for testing were 100 parts per billion

(ppb), 10 ppb, and 1 ppm. Calibration standards were made in TeldarTM bags and used for periodic calibration of the GC during the experiments. Concentrations of 1-BP and 2-

BP were calculated and measured in a syringe and injected in the TeldarTM bag to make the desired concentration of the calibration standard.

3.1.1 Gas Chromatograph (GC)

The Photovac Portable 10Splus Gas Chromatograph (GC) was selected to detect breakthrough because of sensitivity and versatility42. The sample was moved from the point of injection through the column and then out through the detector. The sample was moved through the system by a continuous flow of nitrogen, the carrier gas. The nitrogen flows through the pressure regulator to a sample loop where the sample is introduced.

Then, the nitrogen carries the sample into the column. As the sample is carried through the column, its various components interact with the column packing and are temporarily absorbed and then eventually desorbed. The component is then identified on the instrument if and when breakthrough occurs as the retention time. Figure 2 illustrates the read out of 1-BP on the GC screen when it is detected. The retention time is the peak that is displayed on the instrument. A signal voltage is generated and displayed on the screen resulting in a series of peaks that are separated in time. The chemicals are calibrated throughout the test to assure that the correct chemical is identified on the screen. The retention time of each peak gives an indication of what the contaminant is, while the area and height of the peak indicates how much is present. The chemical of interest is stored

in the library by retention time, peak size, and concentration. This information is automatically updated during calibration. In each sample analysis, peak retention times were compared to retention times in the instrument library. This process assured that the detection method was accurate in detecting the challenge chemicals throughout the test.

The GC utilizes an ultraviolet (UV) lamp of 10.6 electron volts (eV) of energy.

The UV light is emitted from the lamp and is directed at the stream of gas eluting from the column. When the light of the energy hits the eluting molecules, they become ionized. This includes many hydrocarbons, but does not include nitrogen. Most carrier gases like nitrogen have a higher Ionization Potential (IP) over 12eV so they are not ionized.

After the lamp has ionized the compounds, the ionized particles in the detector cell are subjected to a continuous electric field between the repeller electrode and the collector electrode. An electrometer circuit converts the current to a voltage that is then fed to the microprocessor. The microprocessor controls the components of the instrument and interprets and records the readings generated by the UV lamp (otherwise known as the photoionization detector (PID)). A pump continuously pulls the air under test through the sampling loop.

Mass spectra of 1-bromopropane

Figure 2

3.1.2 Real-time Monitor (RTM)

The Photovac photoionization air monitor was selected in conjunction with the GC

as a real-time monitor (RTM) for its accuracy as an analytical method and for possible

field application43. The RTM’s principle of operation is based on the ionization of airborne organic substances using an UV source. The RTM has some of the same functions as the GC but the RTM is limited in analysis capabilities and its detection range.

Air is drawn in the gas inlet and passes to the measurement chamber where a UV lamp generates photons, which ionize certain molecules in the gas flow. Permanent gases in the air such as inert gases, nitrogen, oxygen, carbon dioxide and water vapor are not ionized and therefore do not influence the measurement. The ionization energy is expressed in eV. In order for a substance to be ionized, the ionization energy of the substance to be measured must be lower than the photon energy of the lamp used in the

RTM. The 10.6 eV lamp was used in this study within the detection parameters of the challenge chemicals. The measurement range of the RTM was 0.5 ppm to 2000 ppm with respect to isobutene.

3.2 Breakthrough Testing with ASTM Method

The American Standard Testing Method (ASTM) F-739 is the most common

method for testing chemical resistance in gloves totally immersed in a test chemical.

This method addresses the detection of breakthrough times and permeation rates44. It

simulates the “worst case scenario” of exposure to the test chemical for up to eight hours

(480 minutes) of continuous immersion in the chemical. Breakthrough is the time which elapses between initial contact of a chemical with the outside surface of a protective material and when the chemical can be detected at the opposite surface of the material.

The importance of detecting breakthrough time of chemicals lies in any undetected physical damage to the protective barrier. Some chemicals have permeability rates and go undetected without causing any visible degradation45. This could lead to unanticipated exposure of the wearer to potentially hazardous chemicals and provide a false sense of security of the effectiveness of the barrier. Permeation is a process by which a liquid chemical moves through a protective clothing material on a molecular level. Degradation is a loss in physical properties caused by exposing protective clothing to liquid chemicals45. Once the protective character of the material is diminished, the chemicals penetrate the specimen and eventually come in contact with the wearer.

This study is focuses on the breakthrough time in the process of testing gloves against challenge chemical. Breakthrough time is the most practical application of this study for industry applications. The gloves were also examined for degradation after the tests are complete. In this test procedure, the glove material is used as a barrier separating the liquid challenge chemical from the collection medium air44. The collection medium is periodically sampled, and analyzed quantitatively to determine the concentration of challenge chemical. The time of the first non-zero determination is

“breakthrough”. Breakthrough is therefore depends on the protective material and the sensitivity of the detector.

Glove materials are tested against chemicals to determine which glove is best suited for a given chemical. The continuous contact was designed to simulate conditions

experienced in a work place for up to eight hours or until breakthrough with hands in a hazardous chemical was detected. This testing procedure shows the time it may take for breakthrough to occur. By comparing the different glove materials we can determine the material most suitable for handling a specific chemical.

3.3 Test Procedure

1. Six patches of glove material were cut at the palms of the selected gloves, using a

razor sharp stamper. All other sections of the glove were discarded. Each patch

was tested individually against the two challenge chemicals.

2. The patches were weighed individually using an analytical balance, in

0.001grams. The thickness of each glove patch was measured to the nearest 0.01

mm with a micrometer in three locations. The weight and thickness of each patch

was recorded.

3. A glove patch was randomly selected from the test group of interest and mounted

in the test cell. Patches were placed between the two cell halves (chambers), and

clamped down to ensure proper nitrogen flow, and no leakage of the test

chemical. The two chambers were separated only by the patch cut from the test

glove (see Figure 1).

4. After the test cell was properly assembled, the test cell was connected to the

sample loop. The smaller cell was used to store the challenge chemical. Two

lines were attached to the smaller cell, one for loading and unloading the

chemical, and the other for ventilation.

5. The calibration standards were used to perform calibration of the detection

methods. A calibration check was performed before and after each analysis in

order to ensure test stability. If breakthrough did not occur within 30 minutes,

calibration checks were performed during the test.

6. The GC and RTM were started and the cell was sampled while the challenge

chemical was being loaded in the liquid half of the cell.

7. The challenge chamber was charged with the challenge chemical until the fill

mark on the stem was reached (65-70 mL).

8. The challenge and collecting chamber stems were sealed with ground-glass

stoppers.

9. Once the test cell was loaded with the chemical, the smaller half of the cell

provided a circle with a diameter of 2.4 centimeters of contact area. This low

volume was intended to reduce the amount of chemical needed for testing. The

larger half of the test cell was used for the collection medium.

10. The sample was transported through the column by the flow of nitrogen gas.

11. Nitrogen passed along the inner side of the patch, flushing any chemical to the

detector after its breakthrough. The chemical did not accumulate in the GC or

RTM, as the nitrogen flowed past the patch and carried the chemical through the

sample loop. The sample loop trapped the sample in the nitrogen flow. The

nitrogen flow was then diverted in the opposite direction of the GC.

12. The sample loop valves controlled the amount of gas sample that was directed to

the GC on the sample interval. The RTM continuously detected any changes in

the condition of the test cell.

13. Sampling was discontinued after breakthrough had been definitively established,

or after 480 minutes if breakthrough was undetected. The challenge chemical

passed through the test patch in three phases. The first phase was the absorption

of the chemical molecules into the outside surface of the patch. The second phase

was the diffusion of the molecules in the patch. The third phase was desorption of

the molecules from the inside surface of the patch into the collection medium.

14. After the termination of each experimental run, the glove specimen was visibly

checked for any structural changes.

15. The test cells were changed out. And the test cell used for the previous test was

emptied, cleaned and stored in a fume hood for use in future testing.

The above test was conducted six times for the three different glove materials per

challenge chemical, for a total of thirty-six tests.

3.4 Sampling Regimen

The sampling regimen of this study was selected primarily for experimental convenience.

The ASTM method does not specify a predetermined schedule. Therefore, this sampling regimen was developed after the initial breakthrough was detected in test trials with the

PVC, and nitrile gloves.

• A 2-minute sampling regimen was selected to define a breakthrough period for

PVC gloves.

• A 2-minute sampling regimen was selected to define a breakthrough period for

nitrile gloves.

• A 15-minute sampling regimen was selected to define a breakthrough period for

Silver Shield® gloves.

This sample regimen only applied to the GC and did not apply to the RTM as it continuously sampled for breakthrough of the challenge chemicals.

4 RESULTS

Individual test results are reported in the Summary Chart labeled as Table 2. Other tables and graphs illustrate the results and are compared in this section. The breakthrough times for individual gloves against the two challenge chemicals were reported for each test. Glove material swelling (or lack of) was also noted. Results from the test were documented. Comparisons between glove material, chemicals, and detection methods were presented in this study. Results are listed in this section.

Breakthrough times are summarized in Table 3, 4, & 5. Graphs 1- 6, illustrate the gloves against the challenge chemical with the test averages of the detection methods compared. The results of this study provide evidence that the breakthrough times of some commercially recommended gloves vary when exposed to 1-BP and 2-BP. Breakthrough times were identified for all but one glove material as indicated in the Summary Chart,

Table 2. The data for each test and mean with standard deviation for breakthrough times appear in Table 3.

After the termination of a test, each glove specimen was checked for any visible structural alterations. The degree of swelling was dependant on time, and glove material.

Since no measurements were actually made, the degree of swelling can only be described in qualitative terms. The amount of glove specimen swelling was visibly observed to be equal for each challenge chemical in the PVC gloves. Neither the nitrile nor the Silver

Shield® glove materials visibly exhibited any swelling. Glove thickness differences were found to be statistically insignificant and therefore were not mentioned in the study.

Comparison of 1-BP and 2-BP showed no significant difference in breakthrough times when compared overall as shown in Table 3.

Summary Chart of Breakthrough Time Trial Detection Glove Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Trial 6 Mean Method Material Solvent (mins) (mins) (mins) (mins) (mins) (mins) (mins)

GC PVC 1-BR 7 6 8 6 6 6 6.5

RTM PVC 1-BR 5 5 4 4 6 3 4.5

GC PVC 2-BR 6 6 6 6 6 4 5.67

RTM PVC 2-BR 4 7 6 5 4 3 4.83

GC Nitrile 1-BR 36 40 34 32 38 36 36

RTM Nitrile 1-BR 31 37 31 31 36 33 33.17

GC Nitrile 2-BR 46 40 42 48 44 44 44

RTM Nitrile 2-BR 36 34 38 33 37 36 35.67

Silver GC Shield 1-BR >480 >480 >480 >480 >480 >480 >480

Silver RTM Shield 1-BR >480 >480 >480 >480 >480 >480 >480

Silver GC Shield 2-BR >480 >480 >480 >480 >480 >480 >480

Silver RTM Shield 2-BR >480 >480 >480 >480 >480 >480 >480

Table 3

1-BP and 2-BP Comparisons of Breakthrough Time

Variable Solvent N Lower CL Mean Avg. Upper Std. Dev. Std. CL Error

Test Ave 1-BP 6 -76.28 173.36 423 237.88 97.11

Test Ave 2-BP 6 -73.43 175.03 423.48 236.75 96.65

Test Ave Diff(1-2) - -307 -1.667 303.62 237.32 137.01

Table 4

Glove Comparison of Breakthrough Time

Variable Glove N Lower CL Mean Upper CL Std. Dev Std Material Error

Test Ave Nitrile 4 29.73 37.21 44.69 4.7 2.35

Test Ave PVC 4 3.95 5.4 6.8 0.9 0.45

Test Ave Silver Shield 4 480 480 480 0 0

Diff (1-2) -448.5 -442.8 -437 3.32 2.35

Table 5

GC and RTM Comparisons of Breakthrough Time

Variable Solvent N Lower CL Mean Avg. Upper CL Std. Dev. Std. Error

Test Ave GC 6 -72.8 175.36 423.52 147.61 96.54

Test Ave RTM 6 -76.9 173.03 422.95 238.15 97.226

Test Ave Diff(1-2) -303 651 307.62 237.31 137.01

Table 6

P V C v s. 1 -B rom opr o pa ne B reakt h ro u g h T im e

10 8 s e 6 nut i 4 M 2 0 Trial 1 Tri al 2 Tri al 3 Tri al 4 Tri al 5 Tri al 6 T ria l Re s ult s GC RT M

Graph 1

P V C v s. 2 -B rom opr opa ne B reakt h r ough T im e

10 8 s e t 6 u n 4 Mi 2 0 Trial 1 Trial 2Trial 3Trial 4 Trial 5Trial 6 Tr ia l Re s ult s GC RT M

Graph 2

Graph 3

Nitrile vs. 1-Bromopropane 9 Breakthrough Time 8 7 60 50

s 40

nute 30 i

M 20

0 Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Trial Results

GC RTM

Graph 4

Nitrile vs. 2-Bromopropane Breakthrough Time

s 40 te

nu 30

Mi 20

0 Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Trial 6 Trial Results

GC RTM Graph 5

Nitrile vs. Bromopropane Breakthrough Time Standard Error 60

40 s e t u 30 Min 20

0 GC vs. 1-Bromopropane RTM vs. 1-Bromopropane GC vs. 2-Bromopropane RTM vs. 2-Bromopropane Trials

Graph 6

47 C o m p a r is o n o f D e te c t io n M e th o d s B r e akt hr ough Ti m e 1- B r om opr o pane >4>48080 50

45 40 35 30 s e 25 nut i M 20 15 10 5 0 PVC N i tr i le Si lv e r Sh i e ld G love M a t e r ial

GC RT M

Graph 7

C o m p ar i s on of D e t e ct i on M e t hods B r e akt hr ough Ti m e 2- B r om opr o pane >480 50

30 s e t u 25 in M 20

5 0 PVC N i t r i le S i lv e r Sh i e ld Gl o v e Ma t e r i a l GC RT M

Graph 8

4.1 Results Summary

The results of these tests showed the following:

• The Silver Shield® glove prevented breakthrough by both 1-BP and 2-BP for the

8-hour duration of the test.

• Breakthrough occurred in the nitrile and PVC gloves.

• The PVC gloves were the only gloves that showed degradation to the point of

liquid penetration with both chemicals.

5 DISCUSSION

In this study, time did not allow for testing of a wide selection of gloves, so three commercial gloves were tested. Close attention was given to manufacturers’ recommendations on glove use with different chemicals, and articles by others who conducted glove testing in the past.

Nelson et al., using gas-phase collection with infrared spectrophotmetric analysis, conducted a series of experiments to measure the permeation of 29 different solvents through 28 types of glove materials46. The intent of his experiment was to evaluate and present a method of gas-phase collection. Since so many glove materials were tested for use with individual challenge solvents, breakthrough times varied in many cases.

In another study, Schwope et al. tested the permeation of one chemical (dimethyl sulfoxide) against four different glove materials47. In their study they wanted to identify materials suitable for use with that chemical. Schwope’s study represented the extremes of current permeation research efforts. The author saw the successes of Nelson’s and

Schwope and used their theories in a more condensed study to determine the importance of the variables of the three gloves used in this study.

Berardinelli et al. conducted a glove study comparing different test cells and detection methods48. In his study it was found that the RTM and GC compared as detection methods identified similar breakthrough times for the gloves. Berardinelli et al. used an older model RTM and used water as the collection method, but obviously those variables when changed for this study did not affect the outcome of the results. Similar breakthrough times were found in this study when the RTM and GC were compared.

In a study conducted by Coletta et al., they were able to recommend various protective clothing standards based on breakthrough times; however, they also stated that future standards would probably be based on a maximum allowable flux rather than a breakthrough time49. This has not happened yet and for use in general industry reporting breakthrough times is the most important information obtained in studies.

The author met with one manufacturer and discussed the testing strategy as well as the glove material tested. Glove guides were examined in order to find research of breakthrough times published by different manufacturers. There are times when manufacturers disagree in ratings of glove material. For example, one manufacturer may rate neoprene as an excellent glove for gasoline, while another would not recommend it because of a high permeation rate. Selecting a glove from a retailer or vendor catalog should be only the starting point. Further evaluation by the user is needed if chemical resistance is to be accurately accounted for as effectiveness as a barrier.

Ansell, a glove manufacturer, has also conducted breakthrough and permeation testing for its own gloves against 1-BP41. Their findings concluded no breakthrough occurred in testing of 480 minutes in their laminate glove, Barrier®, which is similar to the Silver Shield® used in this experiment. Ansell’s nitrile glove had a breakthrough of

23 minutes. Ansell only mentions that the PVC glove that they tested had a breakthrough time of less than 10 minutes. Ansell used ASTM-739 testing method but differed in the detection methods and analytical methods used in this study. Ansell used dry nitrogen as the collection medium in their study and used a GC with a flame ionization detector

(FID) as their analytical technique. The RTM and GC were used as detection methods in this study. The ASTM-739 method allows for a variety of testing methods that may

contribute to the variations in breakthrough times when compared to this study. As there is a 10 -13 minute difference in mean breakthrough times found in Ansell’s study and this study, the comparison supports the fact that variability exists in detection methods.

The ASTM has conducted a “round-robin” inter-laboratory evaluation of their test method50. Their findings indicated a fair amount of variation in reported breakthrough times and steady-state permeation rates. They finally concluded that additional testing is required to determine expected variability. ASTM test methods only require that the test be performed in triplicate. Tests were conducted six times to establish reliable data in this study.

The gas-phase collection method works well in establishing breakthrough times because it maximizes the concentration of the gloves tested while simultaneously eliminating unrealistic temperature differences. The author believes that because discrete sampling with the GC was performed at 2 and 15-minute intervals, this method was unable to determine an exact breakthrough time. The RTM was able to take real time readings during testing; however, this detection level was only able to read as low as 0.5 parts per million. Breakthrough may have occurred at a time not captured by either detection method.

The detected breakthrough times are a function of the analytical sensitivity.

Therefore, shorter breakthrough times may have been detected had a lower limit of detection been attained. Of course the contact time resulting in hazardous effects is the most important parameter to define; this is a function of breakthrough time.

The residual concentration for each test run was standardized at 50 parts per billion

(ppb) of challenge chemical per 1.00 sq. cm of continuously contacted (exterior) glove

specimen surface area. Residual concentrations were detected in the GC at concentrations as high as 2.4 ppb.

Protective clothing degradation studies are often times grouped in different categories due to concerns with material weight and volume changes (swellings).

Degradation studies have sought to correlate these changes with breakthrough times in hope of simplifying the glove selection process. Weeks and McLeod have reported that a rule-of-thumb for the relative permeation rate of given solvents through given (glove) materials is that the more the material swells (gain weight) in a given solvent, the greater the rate of permeation of the solvent through the material51. This relationship probably applies in this study as the PVC glove specimen swelled and exhibited a faster breakthrough time in all tests. The Silver Shield® remained visibly intact, and no breakthrough was detected. For the time that it was tested the nitrile glove remained visibly intact, but breakthrough did occur. The nitrile glove may have eventually encountered swelling and degradation if the challenge chemical had remained in contact with the glove. Nitrile gloves were tested for only 45 minutes in this study.

A study conducted by Coletta et al. also addressed the possibility of theoretically predicting glove permeability49. Their findings were that, “such modeling appears to be impractical at this time.” They concluded their study by saying it is impractical to predict permeation in gloves. The author agrees with the results of Coletta’s study as predicting breakthrough times are still impractical and sometimes inaccurate. Obviously, the solubility parameters of a chemical/protective material pair must define their interactions.

As this study tested three glove materials other materials can be tested to assess recommended glove material in the future. At the time that this experiment was

conducted it was not understood why the GC detected 2-BP when testing for 1-BP but

research by OSHA confirmed that 1-BP contained 2-BP1. Consistent data can be obtained when using this testing method for the evaluation of gloves52 53 54.

6 CONCLUSION

This study has achieved its primary objective of determining the breakthrough times for a select group of commercially recommended glove materials using two different detection methods. This study was successful in producing consistent results in all tests.

As hypothesized, of the gloves tested, the Silver Shield® glove offered the most protection from permeation of 1-BP and 2-BP. Silver Shield is an acceptable glove material for general purposes based on this study’s results, as no breakthrough was detected during the 480 minute test. It appears that the Silver Shield® gloves have sacrificed some tear resistance in order to achieve exceptional permeability resistance.

The nitrile glove would be the next preferable choice, but for no more than 30 minutes for each use. Because of the instantaneous breakthrough and degradation observed in PVC gloves during testing, it is not recommended for use while working with

1-BP or 2-BP. Differences between the two chemicals may have contributed to variability in the testing. This was something that was not significant during testing of the gloves against the 1-BP using the GC method, which also detected traces of 2-BP.

Quantitative performance standards are needed in the protective clothing industry.

These standards would encourage further product development, and would permit consumers to identify and select protective materials on a firm testing basis. Some

MSDS only recommend wearing gloves as hand protection, but do not specify what gloves to wear based on glove tests. Manufacturers’ recommendations should be supplemented with permeation/breakthrough time data in order to give an effective delineation of the suitability of the glove material. Therefore, in order to ensure reliable

data, gloves must first be evaluated for each chemical independently, and under conditions to which the worker may be exposed.

Based on the results of over thirty-six permeation tests, it may be concluded that techniques used in this study yielded data which accurately and quantitatively described the behaviors of the challenge chemical/glove pairs. These collection techniques are as effective as those used by previous investigations, but additional testing is required to determine expected intra-laboratory variability. Using either the GC or RTM to detect the breakthrough is a valued resource in assessing breakthrough times for glove material.

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