Occupationally exposed

Reviews on the occurrence, biochemical basis, and treatment of lead toxicity in children (11) and workers (3,12,13) have been pubhshed. Approximately 17% of all preschool children in the United States have blood lead levels >10 //g/dL. In inner city, low income minority children the prevalence of blood lead levels >10 //g/dL is 68%. It has been estimated that over two million American workers are at risk of exposure to lead as a result of their work. PubHc health surveillance data document that each year thousands of American workers occupationally exposed to lead develop signs and symptoms indicative of... 

Human Health Effects. Any assessment of adverse human health effects from PCBs should consider the route(s) of and duration of exposure the composition of the commercial PCB products, ie, degree of chlorination and the levels of potentially toxic PCDF contaminants. As a result of these variables, it would not be surprising to observe significant differences in the effects of PCBs on different groups of occupationally-exposed workers. 

Several studies have reported relatively high levels of PCBs in the semm or adipose tissues of occupationally-exposed individuals, eg, >3000 ppb in the semm (57,58). Not surprisingly, after these exposures were terminated, the PCB semm concentrations tended to decrease (59—61). 

The determinant may be present in biological specimens collected from subjects who have not been occupationally exposed, at a concentration which could affect interpretation of the result. Such background concentrations are incorporated in the BEI value. 

In a case-control study of pesticide factory workers in Brazil exposed to methyl parathion and formulating solvents, the incidence of chromosomal aberrations in lymphocytes was investigated (De Cassia Stocco et al. 1982). Though dichlorodiphenyltrichloroethane (DDT) was coformulated with methyl parathion, blood DDT levels in the methyl parathion-examined workers and "nonexposed" workers were not significantly different. These workers were presumably exposed to methyl parathion via both inhalation and dermal routes however, a dose level was not reported. The exposed workers showed blood cholinesterase depressions between 50 and 75%. However, the baseline blood cholinesterase levels in nonexposed workers were not reported. No increases in the percentage of lymphocytes with chromosome breaks were found in 15 of these workers who were exposed to methyl parathion from 1 week to up to 7 years as compared with controls. The controls consisted of 13 men who had not been occupationally exposed to any chemical and were of comparable age and socioeconomic level. This study is limited because of concomitant exposure to formulating solvents, the recent history of exposure for the workers was not reported, the selection of the control group was not described adequately, and the sample size was limited. 

Some animal studies indicate that dietary exposure to methyl parathion causes decreased humoral and cellular responses (Shtenberg and Dzhunusova 1968 Street and Sharma 1975). A more recent, well-designed animal study that included a battery of immuno/lymphoreticular end points showed few effects at the nonneurotoxic doses tested (Crittenden et al. 1998). No adequate studies are available in humans to assess the immunotoxic potential of methyl parathion. Therefore, studies measuring specific immunologic parameters in occupationally exposed populations are needed to provide useful information. Further studies are also needed to investigate the mechanism for methyl parathion-induced immunotoxicity since this information would help to identify special populations at risk for such effects. 

There are insufficient data to determine potential daily inhalation and dermal exposure levels. However, based on the information presented in Seetions 6.3 and 6.4, exposure levels for the general population are probably very low by these routes. Inhalation exposure is not important for the general population, with the possible exception of those individuals living near areas where methyl parathion is frequently sprayed. Since methyl parathion is readily adsorbed through the skin, dermal eontact may be the most relevant exposure pathway. Dermal eontaet is most likely to oeeur in people who are occupationally exposed. 

Samples of the indoor and outdoor air at the homes of workers occupationally exposed to pesticides, farmers and pesticide formulators, were taken monthly and analyzed for methyl parathion. Methyl parathion was found in 13 of 52 indoor air samples of formulators homes at a mean concentration of 0.26 pg/m (range of 0.04-9.4 pg/m ). Outdoor air samples of formulators homes showed that 3 of 53 samples contained methyl parathion at concentrations ranging from 0.15 to 0.71 pg/m. Methyl parathion was not detected in the indoor and outdoor air samples from farmers homes (Tessari and Spencer 1971). 

Exposures of Children. More studies are needed to assess the exposures of children living in agricultural areas to methyl parathion residues in air, soil, or water. More studies are also needed to assess the exposures of children in the general population to residues of methyl parathion that might be present in food, milk, or water, or on contaminated clothing and skin from occupationally exposed household members. 

In addition to individuals who are occupationally exposed to endosulfan (see Section 5.5), there are several groups within the general population that have potentially high exposures (higher than background levels) to endosulfan. These populations include individuals living in proximity to sites where endosulfan was produced or sites where endosulfan was disposed of, and individuals living near one of the 162 NPL hazardous waste sites where endosulfan has been detected in some environmental media (HazDat 2000). 

Kazen C, Bloomer A, Welch R, et al. 1974. Persistence of pesticides on the hands of some occupationally exposed people. Arch Environ Health 29 315-318. 

B The determinant is usually present in a significant amount in biological specimens collected from subjects not occupationally exposed. 

Stevens-Johnson syndrome, a severe erythema, was seen in five people occupationally exposed to trichloroethylene for 2-5 weeks at levels ranging from 19 to 164 ppm (Phoon et al. 1984). The study authors suggested that the erythema was caused by a hypersensitivity reaction to trichloroethylene. An exfoliative dermatitis (Goh and Ng 1988) and scleroderma (Czirjak et al. 1993), also thought to have an immune component, have been reported in persons occupationally exposed to trichloroethylene. 

Body Weight Effects. Body weight loss has been reported in humans occupationally exposed to trichloroethylene for intermediate or chronic durations at concentrations resulting in neurological effects (Mitchell and Parsons-Smith 1969 Schattner and Malnick 1990). 

Gas pockets in the intestinal coating and blood in the intestines were observed in five male mice treated with trichloroethylene in drinking water at a dose 660 mg/kg/day (Tucker et al. 1982). Similar effects were observed in five male mice at a dose of 217 mg/kg/day, with no mice affected at a doses of 393 or 18 mg/kg/day. Unfortunately, the number of mice examined for this effect was not clearly stated. Although this effect was not dose-related, it is an interesting observation and appears to be consistent with the human cases of gas-filled cysts in the submucosa of the small intestine observed in persons occupationally exposed to trichloroethylene (Nakajima et al. 1990a) (see Section 2.2.1.2). 

Hepatic Effects. Jaundice and abnormal liver function tests including increases in serum transaminase levels have been reported in individuals occupationally exposed to trichloroethylene by both dermal and inhalation exposure (Bauer and Rabens 1974 Phoon et al. 1984). 

The eombined ineidence of stomach, liver, prostate, and lymphohematopoeitic cancers was increased among 2,050 male and 1,924 female Finnish workers occupationally exposed primarily to trichloroethylene (Antilla et al. 1995). The workers were exposed principally through inhalation, although there was some dermal contact. The statistical power of this study was low. 

Cardiovascular Effects. Chronic cardiovascular disease has not been reported in workers occupationally exposed to low levels of trichloroethylene (El Ghawabi et al. 1973), although deaths following acute high-level inhalation exposures to trichloroethylene have been attributed to cardiac arrhythmias. Case studies have described cardiac arrhythmias that in some instances led to death after occupational exposure (Bell 1951 Kleinfeld and Tabershaw 1954 Smith 1966), poisoning (Dhuner et al. 1957 Gutch et al. 1965), or... 

Reproductive Toxicity. Increased miscarriages were reported in one study of nurse-anesthetists exposed to trichloroethylene and other solvents (Corbett et al. 1974). A retrospective case-control study has should an approximate 3-fold increase in spontaneous abortion in women exposed to trichloroethylene and other solvents (Windham et al. 1991). Significant effects on sperm parameters were not observed in men occupationally exposed to trichloroethylene (Rasmussen et al. 1988). Adverse reproductive effects were not noted in humans that ingested water contaminated with trichloroethylene and other solvents (Byers et al. 

Workers at plutonium reprocessing facilities, nuclear reactors, transuranium and low level waste storage facilities, or those engaged in the production or processing of243Am or241 Am may be occupationally exposed to americium. In addition, workers at sites where nuclear testing was conducted may also be exposed to americium. Workers in nuclear power stations may be exposed to airborne radionuclides. The... 

Exposure Levels in Humans. Although some data on the levels of americium in human tissues exposed to natural background levels (food, water, and air) are available, few measurements have been made on the americium content in human tissues. The principal source of information about occupationally exposed individuals is the U.S. Transuranium and Uranium Registries (USTUR) Tissue Program and database, established to document levels and distribution of uranium and transuranium isotopes in human tissues for occupationally exposed workers (USTUR 1999). Several major database files are available. 

DeVathaire CC, Crescini D, Remenieras J, et al. 1998. Monitoring of workers occupationally exposed to radionuclides in France Results from February to August 1997 in the non-nuclear energy field. Rad Prot Dos 79(1-4) 145-148. 

Filipy RE, Hall CA, Kathren RL, et al. 1993. Relationships of soft tissue concentrations of plutonium and americium in occupationally-exposed humans. Health Phys 64(6)(Suppl.) S54. 

Filipy RE, Khokhryakov VF, Suslova KG, et al. 1996. Comparisons of biokinetic models for actinide elements with observed tissue analysis data from occupationally-exposed humans of two countries. Health Phys 70(6)(Suppl.) S82. 

Lagerquist CR, Hammond SE, Bokowski DL, et al. 1972a. Distribution of plutonium and americium in occupationally exposed humans as found from autopsy samples. Health Phys 23(3) 418. 

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