Inhalation exposures route-specific

Immunotoxicity. Only a single case report of skin allergy to methyl parathion has been reported in humans (Lisi et al. 1987). No studies are available in humans exposed to methyl parathion via the inhalation or oral route. Based on limited animal studies, immunotoxicity may be a sensitive end point of methyl parathion-induced toxicity (Shtenberg and Dzhunusova 1968 Street and Sharma 1975). Thus, humans may be at risk for adverse immunological effects following exposure to methyl parathion. The limited information available on the effects of combined exposure to methyl parathion suggest the its toxicity is not route-dependent. Therefore, there is no reason to suspect that the immunotoxic effects observed following oral exposure of animals are route-specific. 

The database for the health effects of endosulfan following ingestion in experimental animals is substantial. However, as can be seen in Figure 2-5, somewhat less information is available on the effects of inhalation and dermal exposure to endosulfan in animals. Furthermore, the health effects associated with acute- and intermediate-duration inhalation and dermal exposure are more fully characterized than those associated with chronic inhalation or dermal exposure. There is no evidence suggesting that the toxicity of endosulfan is route-specific. However, ingested endosulfan should reach the liver sooner. 

Test Species/Strain/Sex/Number Squirrel monkeys, 2-4 males/group Exposure Route/Concentrations/Durations Inhalation exposure at 300,340, or 376 ppm for 15 min 130, 150, or 170 ppm for 30 min 75, 85, or 90 ppm for 60 min Effects Data specifically identifying serious, irreversible effects consistent with the AEGL-2 definition were not available. The lethality data are shown in the summary table for AEGL-3. 

Research studies investigating exposure to JP-8 via oral administration offers an alternative examination of the systemic effects of JP-8 on immune function. Admittedly, this does not ideally mimic occupational exposures, but it does eliminate technical limitations associated with inhalation and dermal penetration of JP-8. It has been suggested that the only route available that can assess the whole mixture (JP-8 in its entirety), without fractionation due to volatilization of components, is the oral route [1] as select components of JP-8 may have increased permeability during dermal exposure, other specific components may be enriched following inhalation exposures[71]. 

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