Hazardous Substances in the Workplace Chapter 20 HAZARDOUS SUBSTANCES IN THE WORKPLACE PAPIYA RAY, MD, MPH,* and CAMERON J.L. NELSON, MD, MPH† INTRODUCTION OCCUPATIONAL EXPOSURE LIMITS Occupational Safety and Health Administration American Conference of Governmental Industrial Hygienists National Institute of Occupational Safety and Health American Industrial Hygiene Association METALS Arsenic Cadmium Chromium ORGANIC EXPOSURES Cyanide Diesel Exhaust Diisocyanates Methylene Chloride Methyl Ethyl Ketone Mustard Agents Organophosphate Nerve Agents Pentachlorophenol Trichloroethylene INORGANIC OR ELEMENTAL EXPOSURES Asbestos Crystalline Silica Tritium White Phosphorus SUMMARY *Occupational Medicine Consultant Physician, Federal Occupational Health, 7700 Wisconsin Avenue, Suite 7201, Bethesda, Maryland 20857 †Commander, Medical Corps, US Navy; Chief of Occupational Medicine, Naval Hospital Bremerton, 1 Boone Road, Bremerton, Washington 98312 367 Occupational Health and the Service Member INTRODUCTION Military personnel are exposed to numerous met- surveillance. There are several governing bodies and als, chemicals, and solvents in the workplace, many of organizations that publish standards for occupational which can have deleterious effects on human health. exposures, which vary in some cases. Because the mili- This chapter provides a short list of chemicals and tary uses different sources for exposure limits, which other hazards common to many military installations. can vary by branch, the limits are not provided here. Included for each chemical is its use, exposure routes, However, in many cases the military uses the most toxicology, and in some cases, recommended medical stringent guidelines recommended. OCCUPATIONAL EXPOSURE LIMITS Occupational exposure limits can be either legally sionals that publishes exposure guidelines known as enforceable standards established by regulatory agen- threshold limit values (TLVs) and biological expo- cies or guidelines determined by research groups. sure indices (BEIs).3 Unlike OSHA PELs, these are In either case, the goal of these exposure limits is to recommendations and not legal standards. They are protect workers over their entire working lifetime. based solely on health factors with no consideration The most commonly encountered organizations are of economic or technical feasibility and, therefore, described below. tend to be more stringent than OSHA levels. In addition to the time-weighted average and ceiling Occupational Safety and Health Administration limit, for certain substances, the ACGIH defines a short-term exposure limit as the concentration below The Occupational Safety and Health Administra- which workers can be exposed for a period of up to tion (OSHA) is a federal agency in the Department 15 minutes. of Labor. OSHA issues workplace health and safety regulations, such as exposure limits, employee ac- National Institute of Occupational Safety and cess to information, conditions governing the use of Health personal protective equipment, and requirements for safety procedures. It is also responsible for enforcing The National Institute of Occupational Safety and its standards.1 Health (NIOSH) is a federal agency under the Centers OSHA promulgates permissible exposure limits for Disease Control and Prevention. It is responsible (PELs), which are legally enforceable standards.2 for conducting research and making recommenda- PELs are set based on chronic exposure and indicate tions for the prevention of work-related injury and the maximum values for the “employee’s average air- illness.4 NIOSH publishes recommended exposure borne exposure in any 8-hour work shift of a 40-hour limits (RELs). As with TLVs and BEIs, RELs are work week which shall not be exceeded”; otherwise generally updated more frequently and are stricter known as the 8-hour time-weighted average.2 For than PELs. certain substances, OSHA has also set ceiling limits, the concentration of the substance that should never American Industrial Hygiene Association be exceeded. The OSHA action level is set at half the PEL value and indicates the level at which medical The American Industrial Hygiene Association surveillance should be initiated. (AIHA) is a professional association, like the ACGIH. Its major goals are the advancement of the study American Conference of Governmental Industrial and control of industrial health hazards, and the dis- Hygienists semination of technical knowledge.5 AIHA publishes workplace environmental exposure levels (WEELs), The American Conference of Governmental which are health-based guidelines published annu- Industrial Hygienists (ACGIH) is a professional as- ally. Like RELs, TLVs, and BEIs, WEELs are not legally sociation of industrial hygienists and related profes- enforceable. 368 Hazardous Substances in the Workplace METALS Arsenic Toxicology Forms Inorganic arsenic compounds have been recognized as a human poison since ancient times.7 Arsenic is an Arsenic is a naturally occurring metal.6 It exists irritant to the skin and gastrointestinal tract and has in several forms: elemental, inorganic, organic, and numerous long-term health effects. Unfortunately, gaseous. Elemental (or metallic) arsenic is a steel little is known about the effects of organoarsenic grey solid material. Arsenic more commonly exists compounds in humans. Studies in animals show that as inorganic salts, in one of three oxidation states: -3, most organoarsenic compounds are less toxic than +3, or +5. Organic arsenic compounds can be further the inorganic forms but still have toxic effects on the described as organometals, otherwise known as or- digestive and urinary tracts. ganoarsenic compounds, characterized by a chemical Acute toxicity. Acute arsenic poisoning commonly bond between arsenic and one or more carbon atoms. occurs when arsenic is ingested in large doses as inor- In inorganic form, arsenic generally combines with ganic arsenic. This occurs when arsenic has contami- oxygen, chlorine, or sulfur. Arsine is the gaseous nated drinking water wells, but it does not routinely form of arsenic. occur in the occupational setting. Individuals who in- gest large quantities of inorganic arsenic will develop Uses symptoms within minutes to hours after exposure. Symptoms can range from gastrointestinal discomfort, Elemental arsenic is used as an alloying agent in including nausea and vomiting, to severe abdominal ammunition and solders, an antifriction additive for pain, abdominal cramps, and profuse diarrhea. In the bearings, and a structural strengthening agent for worst cases, hepatic necrosis associated with markedly lead batteries. Organoarsenic compounds, namely elevated liver enzyme levels and acute renal failure can cacodylic acid, disodium methyl arsenate, and mono- occur. Cardiovascular effects can also result from acute sodium methyl arsenate, are used as pesticides. Other arsenic poisoning.7 Seizures, coma, and circulatory col- organoarsenic compounds are used as additives in lapse leading to death may result when individuals are animal feed to control intestinal coccidian parasites exposed to more than 70 mg of arsenic. Persons who in some poultry and swine farms. Inorganic arsenics, recover from acute arsenic poisoning may develop such as arsenic acid, arsenic pentoxide, and arsenic delayed peripheral neuropathy, which presents as trioxide, are also used as pesticides in the United States. symmetrical sensory loss in the distal lower extremities. Arsenic trioxide and arsenic acid are also decolorizers Arsenic dusts and vapors are both respiratory and and fining agents used in the production of bottle eye irritants. Inhalational exposure of arsine gas results glass and other glassware. Finally, arsine gas is used in intravascular hemolysis. The initial symptoms of in the microelectronics industry for gallium-arsenide exposure include headache, nausea, and chest tight- semiconductor production and as a source of dopant ness. Shortly afterward, the triad of abdominal pain, arsenic atoms. jaundice, and oliguria develop. Death can occur if exposures exceed 10 ppm. Routes of Exposure Chronic toxicity. The skin is the major target organ in chronic inorganic arsenic exposure. Long-term Arsenic compounds can be ingested, inhaled, and ingestion produces characteristic skin changes on the absorbed through the skin. The efficiency of absorp- palms of the hands and feet, including hyperkeratosis tion depends on the form of arsenic, its solubility, and and hyperpigmentation with spots of hypopigmen- the route of exposure. In general, both organic and tation. Workers chronically exposed to arsenic also inorganic forms of arsenic are well absorbed through experience these dermal manifestations. Individuals the gastrointestinal tract, but dermal uptake is low. In- who have a history of chronic arsenic ingestion have halational exposure usually occurs only with trivalent an elevated risk of skin cancer, including basal cell and arsenic oxide or arsine gas. squamous cell carcinoma. 369 Occupational Health and the Service Member Peripheral neuropathy can develop in individu- Uses als who have chronic low-level arsenic ingestion. The neuropathy is sensory in nature and includes The most common use for cadmium is as an active paresthesia or numbness; in severe cases, the periph- electrode material in nickel-cadmium batteries. Cad- eral neuropathy can affect the motor neurons. Liver mium compounds are also used for electroplating and damage and peripheral vascular disease can also to impart corrosion resistance to