Human exposure studies ingestion effects

Figure 3-5 graphically depicts the information that currently exists on the health effects of methyl parathion in humans and animals by various routes of exposure. The available literature reviewed concerning the health effects of methyl parathion in humans described case reports of longer-term studies of pesticide workers and case reports of accidental or intentional ingestion of methyl parathion. The occupational exposure is believed to be via the dermal and inhalation routes. The information on human exposure is limited in that the possibility of concurrent exposure to other pesticides or other toxic substances cannot be quantified. 

Mineral Oil Hydraulic Fluids. There is limited information on the toxicity of mineral oil hydraulic fluids in humans. A single case report of a child accidentally ingesting a single dose of automotive transmission fluid provides limited information on death and systemic effects. A case-control study provides some information on the carcinogenicity of mineral oil hydraulic fluids. The study population was exposed via inhalation and dermal routes. An occupational exposure study provides information on neurotoxicity following chronic dermal exposure. Information on the toxicity of mineral oil hydraulic fluids is limited to a series of inhalation, oral, and dermal acute-duration exposures. These studies provide information on death, systemic effects, and neurotoxicity by inhalation, oral, and dermal routes, and immunotoxicity following dermal exposure. 

Epidemiological and Human Dosimetry Studies. There are reports on the adverse effects of endrin in humans (Section 2.2). These reports involve acute exposures in people who ingested endrin-contaminated food (Curley et al. 1970 Davies and Lewis 1956 Waller et al. 1992 Weeks 1967). There are also studies of workers with acute exposures to contaminated air (Hoogendam et al. 1962, 1965). Existing studies identify the nervous system as a major target associated with exposure to endrin. 

Hepatic Effects. Liver effects reported in case studies in humans exposed to 1,4-dichlorobenzene via inhalation have included jaundice, cirrhosis, and atrophy (Cotter 1953). Estimates of exposure duration ranged from 1 to 18 months however, quantitative data on 1,4-dichlorobenzene levels were not available. One report was located that described a 3-year-old boy who may have ingested 1,4-dichlorobenzene crystals. Jaundice was reported, indicating that liver function was in some way compromised, although no further details were reported. No dermal exposures to 1,4-dichlorobenzene in humans were reported. The lack of reliable information regarding human exposures to 1,4-dichlorobenzene by all three routes of exposure makes it difficult to draw any helpful conclusions about the toxicity of 1,4-dichlorobenzene in humans. 

No studies were located regarding developmental effects of various forms of aluminum following acute-or chronic-duration oral exposure in healthy humans. The only human data on developmental effects come from infants with renal failure and premature infants. Their responses are probably not indicative of responses expected in normal infants. Osteomalacia and increased bone and serum levels of aluminum were reported in 3 infants with kidney failure who had been treated orally with more than 100 mg of Al/kg/day as aluminum hydroxide from the first or sixth month of life (Andreoli et al. 1984 Griswold et al. 1983), and in healthy infants ingesting aluminum-containing antacids (Pivnick et al. 1995). 

Most of the information on the toxicity of white phosphorus in humans comes from case reports of individuals who intentionally or accidentally ingested a single dose of phosphorus that was a component of poison or fireworks. These case reports provide information on acute systemic effects, possible immunological effects, neurological effects, reproductive effects, and death in humans. In addition to these case reports of single exposures, there are several case reports of children ingesting white phosphorus for an intermediate duration these studies provide information on intermediate systemic effects and developmental effects. Information on chronic oral and dermal exposure in humans is limited to occupational exposure studies in which workers were exposed to white phosphorus via inhalation, oral, or dermal routes. Some limited information on chronic systemic effects is available from these studies. There is limited information on the toxicity of inhaled white phosphorus in humans. Several occupational exposure studies are available however, only a limited number of parameters were assessed in these studies. 

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