Dermal exposure during inhalation studies

Serum endosulfan was 4 pg/L at 30 hours after an agricultural pilot was exposed dermally (and probably also by inhalation) for approximately 45 minutes in clothing that was heavily contaminated with endosulfan and methomyl (Cable and Doherty 1999) the dermal exposure level was not estimated and no other measures of tissue levels of endosulfan were obtained. A study by Kazen et al. (1974) has identified endosulfan residues on the hands of workers after relatively long periods free from exposure. Endosulfan residues were identified on the hands of one worker approximately 30 days after exposure and on the hands of one worker who had not used endosulfan during the preceding season. 

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]. 

No acute-duration inhalation MRL could be derived for mirex because no inhalation data could be located. No acute-duration oral MRL was derived for mirex because serious effects (heart block and arrhythmias in fetuses from dams exposed during gestation) were observed at the lowest dose tested (Grabowski 1983a). Studies examining the effects of mirex and chlordecone after acute-duration dermal exposure would be helpful since persons at hazardous waste sites may be exposed dermally to mirex. Additional dermal studies are certainly necessary because skin absorption of chlordecone appears to be an important route of exposure (Taylor et al. 1978). However, populations at hazardous waste sites are unlikely to be exposed via inhalation since these substances are virtually nonvolatile, so future studies using this route of exposure are not essential. 

PET itself is biologically inert if ingested and is dermally safe during handling. No adverse effects have been observed at exposures anticipated to occur from the use of PET packages (International Life Sciences Institute, 2000). It poses no hazard if inhaled and no evidence of toxicity has been detected in feeding studies using animals. 

Absorption, Distribution, Metabolism, and Excretion. Quantitative data on the absorption of radium after intake via any exposure route are very limited. No data were located on the absorption of radium after dermal exposure. Information on laboratory workers exposed to radium during an industrial accident indicates that absorption can occur via the inhalation route. A study in elderly human subjects indicated that at least 20% of the ingested radium-224 in mock radium dial paint was absorbed and retained. No studies were located on the absorption of radium by animals after inhalation or dermal exposure. A study of orally exposed rats indicated that retention of radium at 400 to 500 days was 1% to 7% of the administered dose. Further studies to investigate the absorption and retention of radium after inhalation, oral, and dermal exposure would be helpful in elucidating the relative risks associated with exposure by each route. 

Of primary concern in exposure studies is the amount of compound actually entering the body via ingestion, inhalation, or dermal absorption. In order to evaluate the effectiveness of patches in predicting the absorbed dose, during two studies we attached patches to the clothing at strategic locations in addition to collecting total urine samples. As an example of the fluctuation in 2,4,5-T exposure from one patch to another, Table 1 provides information derived from individual patch analyses from four mist blower crewmembers. 

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