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notes to add

NIOSH bulletin board

• hello
• January 20, 1975
• "Du Pont had begun looking closely at this substance recently because of the similarity in chemical structure with vinyl chloride. Du Pont has utilized chloroprene in the production of neoprene (polychloroprene) since 1931."
• "The primary responses to chloroprene appear to be central nervous system depression and significant injury to lungs, liver, and kidneys.1 Humans exposed to chloroprene have been reported to develop dermatitis, conjunctivitis, corneal necrosis, anemia, temporary loss of hair, nervousness, and irritability. 6"

Chloroprene

Introduction

The chemical structure of chloroprene.

Chloroprene is the common name for 2-chlorobuta-1,3-diene (IUPAC name) and has the chemical formula CH₂=CCl−CH=CH_2. Other names for chloroprene include chlorobutadiene or beta-chloroprene. Chloroprene is a chemical almost exclusively used as a monomer for the production of the polymer polychloroprene, a type of synthetic rubber. Polychloroprene is better known to the public as Neoprene, the trade name given by DuPont. Chloroprene does not occur naturally in the environment, but is rather produced in three steps from 1,3-butadiene. Chloroprene is a highly volatile, flammable, colorless liquid with a “pungent and ether-like” odor. The melting point of chloroprene is -130 degrees Celsius and the boiling point is 59 degrees Celsius. Spontaneous reactions of chloroprene may include polymerization, dimerization, oxidation, epoxidation, and nitration. The chemicals vinyl chloride and butadiene are relevant hazards due to their structural similarity to chloroprene.

History of Chloroprene

Rubber, originally used by indigenous communities, quickly transformed into a desirable product all across Europe once it was discovered in the 1800s. Only a century later, automobiles were invented which pushed the rubber demand passed its carrying capacity and incited a race to discover a form of synthetic rubber that would meet these new needs. In 1923, Julius A. Nieuwland, a researcher who was exploring chemical reactions using acetylene gas, synthesized a precursor, chloroprene, for synthetic rubber. A chemist a part of DuPont Corporation’s research group of Wallace Hume Carothers then discovered that chloroprene could be polymerized into a new rubber-like product, neoprene. Today, 90% of chloroprene is used to manufacture neoprene and the remaining 10% is used to produce polychloroprene liquid dispersions.

Production of Chloroprene

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Acetylene Process

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Transportation Regulations

*keep the same*

Occupational Health and Safety

Occupational Exposure Limits

The official legal body that develops and enforces occupational exposure limits (OEL) in order to ensure workplace safety and health regulations is the Occupational Health and Safety Administration (OSHA) that works under the U.S. Department of Labor. OSHA's permissible exposure limits (PELs), a guideline for occupational exposures, were adopted from the 1968 threshold limit values (TLVs) of the American Conference of Governmental Industrial Hygienists (ACGIH). Each year, the ACGIH publish their TLV and BEI booklet that provides updated information on "occupational exposure guidelines for more than 700 chemical substances and physical agents." The scientific literature on certain chemical and physical exposures has evolved since 1968, therefore OSHA recognizes that their PELs may not guarantee worker health and safety. The National Institute for Occupational Health and Safety (NIOSH) under the U.S. Department of Health and Human Services compensates for the rigidity of the PEL by researching "all medical, biological, engineering, chemical, and trade information relevant to the hazard" and publishing recommended exposure limits (RELs) based on their research. Therefore, as a way to ensure worker safety and health, the following sections on safety guidelines and hazard control will consider the most recent occupational exposure limits from ACGIH's 2018 TLV and BEI booklet and NIOSH's REL.

Occupational Exposure Limits for Chloroprene

Organization	Concentration
NIOSH REL	1 ppm
ACGIH TLV 8-hour TWA	1 ppm
OSHA PEL 8-hour TWA	25 ppm
Mine Safety and Health Administration	25 ppm
Austria OEL MAK-TMW	5 ppm
Belgium OEL TWA	10 ppm
Denmark OEL ceiling concentration	1 ppm
Finland OEL TWA	1 ppm
France OEL VME	10 ppm
Hungary OEL TWA	5 ppm
Iceland OEL Short Term Exposure Limit (STEL)	1 ppm
Korea OEL TWA	10 ppm
Mexico OEL TWA	10 ppm
New Zealand OEL TWA	10 ppm
Norway OEL TWA	1 ppm
Peru OEL TWA	10 ppm
Poland OEL MAC TWA	0.55 ppm
Russia OEL STEL	0.55 ppm
Sweden OEL TWA	1 ppm
Switzerland OEL MAK-week	5 ppm
The Netherlands OEL MAC-TGG	5 ppm

In the ACGIH's 2018 TLV and BEI booklet, chloroprene was designated with a skin and an A2 notation. The skin notation designation is based off of animal and human research that have shown chloroprene's ability to be absorbed by the skin. An A2 designation by the ACGIH means that the substance is a suspected human carcinogen with support from human data that are accepted as adequate in quality but may not be enough to declare an A1 (known human carcinogen) designation. Additionally, the TLV basis for these designations are due to scientific studies that show an association between chloroprene exposure and lung cancer, upper respiratory tract (URT) and eye irritation.

Exposure Routes

Possible routes of chloroprene exposure that may affect a worker include inhalation, skin absorption, ingestion, and skin or eye contact. Those who work in close contact with chloroprene should take extra precaution to avoid chloroprene exposure. Due to possible skin absorption of chloroprene, biological monitoring programs should be implemented in the work place to track health risks from chloroprene skin absorption.

Hazards

As a way to visually communicate hazards associated with chloroprene exposure, the United Nations Globally Harmonized System of Classification and Labeling of Chemicals (GHS) has designated the following hazards for exposure to chloroprene: flammable, toxic, dangerous to the environment, health hazard and irritant.

insert HAZCOM symbols here.

Hazard communication (HAZCOM) pictogram warning of acute toxicity. The pictogram is named "Skull and Crossbones."

Hazard communication (HAZCOM) pictogram warning of acute toxicity. The pictogram is named "Flame."

There are two broad categories for hazards as defined by OSHA: physical and health hazards. Reactive, fire, and explosion hazards are under physical hazards. And systemic effects and target organ effects are under health hazards. Chloroprene is a flammable liquid because flash point is below 100 degrees F.

Fire Hazard

Chloroprene poses fire hazards because it is highly flammable as a liquid and as a vapor. For this reason, chloroprene is very dangerous upon exposure to heat or flames. As a vapor, chloroprene is heavier than air. Fire hazard controls should account for chloroprene traveling along lower lying areas in the workplace. In order to control potential chloroprene fires, carbon dioxide, dry chemicals and water spray may be used.

Health Hazard

Exposure to chloroprene affects the target organs of the eyes, skin, respiratory system and reproductive system and with prolonged or repeated exposure, chloroprene may cause serious damage to these organs. The primary route of exposure to chloroprene is by inhalation or dermal exposure and therefore, may cause irritation of the skin, upper respiratory tract, and eyes.

Those who are acutely exposed to high concentrations of chloroprene may show signs of headache, irritability, dizziness, insomnia, fatigue, giddiness, respiratory irritation, cardiac palpitations, chest pains, nausea, gastrointestinal disorders, dermatitis, temporary hair loss, conjunctivitis, and corneal necrosis. Those who are chronically exposed to chloroprene may have the following symptoms: liver function abnormalities, disorders of the cardiovascular system, and depression of the immune system.

The Environmental Protection Agency (EPA) designated chloroprene as likely to be carcinogenic to humans based off of evidence from studies that showed a statistically significant association between occupational chloroprene exposure and the risk of lung cancer.

Biological Hazards

• biomonitoring programs
• medical surveillance

Handling and Storage

The high vaporization potential and flammability of chloroprene has significant implications for handling and storage operations in the occupational setting. Chloroprene should be stored in closed containers in a cool, well-ventilated area with the temperature no higher than 50 degrees Fahrenheit. In addition, chloroprene has a high reactivity and should be stored away from oxidizing agents such as perchlorate, peroxides, permanganates, chlorates, nitrates, chlorine, bromine, and fluorine. All activities inducing a potential fire hazard should be avoided. For instance, smoking, having open flames or using sparking tools to open or close storage containers should be prohibited. It is also advised that grounded and bonded metal containers are used for the transport of chloroprene.

Workplace Controls and Practices

The primary occupational concern for chloroprene is limited to the facilities manufacturing chloroprene and using chloroprene to produce the synthetic rubber, polychloroprene. NIOSH developed a list of actions to address specific workplace hazards. These actions are represented in their diagram of the "Hierarchy of Controls" shown below with the most effective steps at the top and the least effective at the bottom. The first step addressing possible workplace hazards is to consider physically removing the hazard via elimination. If elimination is not possible, substitution should be considered. No intentions of eliminating the use of or substituting chloroprene have been identified. Therefore, occupational control of chloroprene exposure relies upon engineering controls, administrative controls, and personal protective equipment. Recommended engineering controls of chloroprene include isolating chloroprene operations, installing local exhaust ventilation in those areas, and implementing safety monitors that can check if an explosive amount of chloroprene is present in these chloroprene-isolated areas. Administrative controls serve an important way to encourage good work practices. Workers who may be exposed to chloroprene should wash their hands before eating, drinking, smoking, or using the restroom. Furthermore, these work areas should be separate from eating, drinking, and smoking areas. Contaminated work clothing should be changed before leaving the workplace premises. Additionally, eye wash and shower facilities should be readily available for workers in case of emergency exposure. For the last control method for exposure to chloroprene, it is recommended that clean gloves and clothing are worn each day and that wearing contact lenses is avoided. Skin and eye contact should be prevented. If exposure concentrations exceed OELs, a NIOSH approved supplied-air respirator with a full face piece is recommended. Those working with chloroprene should be provided clear communication regarding the occupational hazards associated with chloroprene. Communication should fall in compliance with OSHA's Hazard Communication Standard (HCS) which regulates that companies dealing with chemicals provide a Safety Data Sheet (SDS) for the chemical in use and label such chemicals with HCS hazard symbols. Employees must have access to this hazard information, understand associated hazards and be trained on how to handle the chemical correctly in order to avoid occupational risks associated with chloroprene exposure.

Public Health Implications

Since chloroprene usage is limited to those facilities producing Neoprene, the occupational health risks are isolated to those facilities. However, insufficient control of chloroprene emissions may extend the health and safety concerns of chloroprene beyond the facility and into the surrounding areas. Chloroprene release is predominately as an air pollutant, but other feasible fates and transport of chloroprene in the environment are discussed below.

Fate and Transport

In the fourteenth edition of the National Institute of Health report on carcinogens, the half-life time differences between chloroprene in air, water and soil were highlighted. In the air, chloroprene “reacts with photo-chemically generated hydroxyl radicals” and has a half-life of 18 hours. The smaller amounts that are removed by reaction with ozone have a half-life of 10 days. In streams, chloroprene is stated to volatilize quickly with a half-life of 3 hours. However, in bigger bodies of water such as a lake, the half-life of chloroprene is 4 days. Similar to its reaction with water, chloroprene on soil was cited to volatilize from the surface. However, the report remarked that chloroprene holds the potential to leach into groundwater supplies. Due to its volatility and extreme reactivity, the threat of chloroprene exists predominantly as an air pollutant and is not expected to bioaccumulate or persist in the environment according to the U.S EPA Toxicological Review of Chloroprene. However, the Centers for Disease Control and Prevention (CDC) states that chloroprene does, in fact, have the potential to persist in the environment. Nonetheless, the primary route of exposure for animals and humans is inhalation, but can be absorbed through the skin or indigestion.

Environmental Release of Chloroprene

In December 2015, the EPA released its 2011 National Air Toxic Assessment to help state and local agencies prioritize the required steps in identifying and mitigating sources of air pollution. In this report, it was measured that chloroprene was being released from Denka Performance Elastomer’s Pontchartrain facility located in LaPlace, Louisiana. EPA worked with the Louisiana Department of Environmental Quality, DuPont and the nonprofit organization Louisiana Environmental Action Network to institute monitoring of chloroprene pollution near the facility and in the surrounding neighborhood. Air monitoring is ongoing.

Bibliography of Sources (textbooks, literature reviews, reliable publications by experts within the field)

1. Bulbulyan, M.A., Changuina, O.V., Zaridze, D.G. et al. Cancer Causes Control (1998) 9: 381. https://doi-org.ezp-prod1.hul.harvard.edu/10.1023/A:1008863516506 CASE STUDY IN RUSSIA
2. https://nj.gov/health/eoh/rtkweb/documents/fs/0407.pdfNew Jersey Department of Health and Senior Services, published October 1994, revised February 2011, Hazardous Substance Fact Sheet OCCUPATIONAL
3. U.S. EPA. IRIS Toxicological Review of Chloroprene (Final Report) (2010). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-09/010F, 2010. GENERAL
4. Rickert, Annette, et al. “A fatal intoxication by chloroprene.” Forensic Science International, vol. 215, no. 1-3, 2012, pp. 110–113.
5. “CHLOROPRENE.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 1 July 2014, www.cdc.gov/niosh/ipcsneng/neng0133.html. GENERAL
6. Bukowski JA. (2009). Epidemiologic evidence for chloroprene carcinogenicity: Review of study quality and its application to risk assessment. Risk Analysis 29(9):1203–1216. EPI STUDY
7. “DENKA Air Monitoring Summary Sheet.” EPA in Louisiana, Environmental Protection Agency, Oct. 2017, www.epa.gov/sites/production/files/2017-11/documents/r6_summary_through_october_20_2017_0.pdf. CHLOROPRENE IN LA
8. Eckert, Elisabeth, et al. “Excretion of mercapturic acids in human urine after occupational exposure to 2-Chloroprene.” Archives of Toxicology, vol. 87, no. 6, May 2013, pp. 1095–1102. BIOMONITORING
9. Esmen, Nurtan A., et al. “Chemical process based reconstruction of exposures for an epidemiological study.” Chemico-Biological Interactions, vol. 166, no. 1-3, 2007, pp. 254–263. EPI STUDY
10. Leonard, Robin C., et al. “Comparison of standardized mortality ratios (SMRs) obtained from use of reference populations based on a Company-Wide registry cohort to SMRs calculated against local and national rates.” Chemico-Biological Interactions, vol. 166, no. 1-3, 10 Sept. 2006, pp. 317–322. EPI STUDY
11. Marsh GM, Youk AO, Buchanich JM, Cunningham M, Esmen NA, Hall TA, and Phillips ML. (2007a). Mortality patterns among industrial workers exposed to chloroprene and other substances: I. General mortality patterns. Chemico-Biological Interactions 166(1-3):285–300. EPI STUDY
12. Marsh GM, Youk AO, Buchanich JM, Cunningham M, Esmen NA, Hall TA, and Phillips ML. (2007b). Mortality patterns among industrial workers exposed to chloroprene and other substances: II. Mortality in relation to exposure. Chemico-Biological Interactions 166(1-3):301–316. BIOMONITORING
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14. Mundt, Kenneth, et al. “THE IRIS REVIEW PROCESS: CHLOROPRENE AND THE CRITICALITY ...” Examining the Scientific and Operational Integrity of EPA’s Iris Program, Ramboll Environ, 9 Aug. 2016. COUNTERVIEW
15. “Neoprene (CR).” Encyclopædia Britannica, Encyclopædia Britannica, inc., 3 July 2015, www.britannica.com/science/neoprene. HISTORY
16. Pell S. (1978). Mortality of workers exposed to chloroprene, Journal of Occupational Medicine 20:21–29. CASE STUDY
17. Trochimowicz HJ, Loser E, Feron VJ, et al. “Chronic Inhalation Toxicity and Carcinogenicity Studies On-Chloroprene in Rats And Hamsters.” Inhalation Toxicology, vol. 10, no. 5, 1998, pp. 443–472. TOXICOLOGY
18. U.S. EPA. 2011 National Air Toxics Assessment (2015). U.S. Environmental Protection Agency, Washington, DC. https://www.epa.gov/national-air-toxics- assessment/2011-national-air-toxics-assessment GENERAL
19. Yang Y, Himmelstein MW, and Clewell HJ. (2012). Kinetic modeling of b- chloroprene metabolism: Probabilistic in vitro–in vivo extrapolation of metabolism in the lung, liver and kidneys of mice, rats and humans. Toxicology in Vitro 26:1047–1055. TOXICOLOGY
20. National Toxicology Program, Department of Health and Human Services. “Chloroprene.” Report on Carcinogens, Fourteenth Edition, 3 Nov. 2016. GENERAL
21. Allen, B.c., et al. “A constrained maximum likelihood approach to evaluate the impact of dose metric on cancer risk assessment: Application to β-Chloroprene.” Regulatory Toxicology and Pharmacology, vol. 70, no. 1, 2014, pp. 203–213. TOXICOLOGY
22. Environmental Protection Agency. “Action Plan.” DENKA PERFORMANCE ELASTOMER, LLC – PONTCHARTRAIN FACILITY, June 2016. CHLOROPRENE IN LA
23. https://m.restek.com/documentation/msds/30238_useng.pdf Restek Safety Data Sheet for Chloroprene. OCCUPATIONAL
24. https://www.epa.gov/sites/production/files/2018-01/documents/epa_repsonse_to_mr._holdren_jan_25_2018_complete.pdf EPI STUDY REVIEW IN RESPONSE TO REQUEST FOR CORRECTION BY ROBERT HOLDEN THE ATTORNEY DENKA PERFORMANCE ELASTOMER LL