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5' <br /> F FTherefore) the current concentrations of 1.1-DCE may be higher now than in the <br /> past. <br /> the most prominent nt contaminant, is readily absorbed through all three routes of <br /> exposure: <br /> cerrnal contact ingestion, and inhalation. Regardless of the route of exposure, <br /> once absorbed into the body, TCE is widely distributed and rapidly metabolized and <br /> ted. The rapid elimination of TCR(greater than 90 percent is eliminated within 2 <br /> eliminated. <br /> hour's <br /> akes iirnt ractical to evaluate possible biomarl ers e.g., levels of T its <br /> ts <br /> metabolites in body tissues indicators of past exposures ATS 1995a). Exposure <br /> reconstruction estimates therefore must rely on contaminant plume envirommental <br /> exposure models that take into account such things as contaminant plume and aquifer <br /> characteristics along <br /> with background information such as history of use or the location <br /> of the spill or release. <br /> The principal health concerns that may be associated with levels of TCE exposure such as <br /> hose Found in the Mashpee wells are developmental and neurotoxic effects. <br /> Developmental effects, specifically cardiac anomalies, have been observed Un# both human <br /> populations and experimental animals. while these studies have flaws such a imprecise <br /> pope <br /> individual exposure estimates and other nixed exposures, they are consistent with one <br /> another in exhibiting heart-related problems. Because they appear to be the most sensitive <br /> indicator of adverse health effects, developmental effects form the basis of ATS <br /> rxinirx�u�r risk levels Ls , The oral �L for WE for exposures occurring up to one <br /> year is 2 ug/kg/day i.e. intermediate duration exposure). This MRL was set 1 trines <br /> lower than the lowest dose at which developmental effects were observed. QT'S <br /> DR <br /> 1995a) <br /> the estimated TC exposure for the adult residents o 2 Lot 2 1'between 1993 an <br /> s <br /> 1996 was 64 ug/kg/day for the worst ease scenario i.e., exposed to 1000 ppb for 3 <br /> months) and 32 ug/kg/day for the reasonable exposure scenario i.e., exposed to 507 ppb <br /> months)" Every though these exposures are higher than the MRL, they are still below <br /> for g <br /> the levels at which health affects are expected. Also, because A ' 62 Lot 241 has been <br /> occupied exclusively by adults from 1993 to the present, the developmental toxicity of <br /> TCE would not be a concern for the occupants of this residence. Other adverse health <br /> effects that have been reported to be associated ith exposure to T C (e.g., cardiac <br /> arrhythmias, renal and liver problems, dryness and neurological symptoms have only . <br /> yt � p <br /> reported t substantial) higher levels (e.g., a thousand fold higher). These types obeen repo 'effects have been most commonly reported following workplace exposures, anaesthesia, <br /> and intentional exposure (ATSDR 1995a). Therefore, these residents opportunities for <br /> exposure to TC are not expected to result in adverse health effects. <br />� <br /> The residents of AP 62 Lot 241 from 1986 to 1993 did not have any opportunities for <br /> exposure to TC (see Fable 3a . <br /> The estimated TCE exposures for adults and children at AP 62 hot 72 under worst case <br /> conditions exposed to 43 b for 1 ear were and 14 ug/kg/day,respectively. <br /> or�d�t� n (i.e., exp pp <br /> le exposure scenario i.e., exposed to 4. ppb for 1 year), <br /> estimated exposures for <br /> the <br /> However, under the reasonable <br /> these two populations tions and 1.4 ug/kg/day, respectively)were <br /> 11 <br />