TOXICOLOGICAL PROFILE FOR CHROMIUM - Davidborowski.com

CHROMIUM 3075. POTENTIAL FOR HUMAN EXPOSUREmay affect the bioavailability of contaminants in several ways. The most likely manner is by acting as acompetitive sink for the contaminants. In the presence of soil, the contaminants will partition betweenabsorption by the gut and sorption onto the soil particles. If a soil has a longer residence time in the gutthan food particles, sorption may enhance the overall absorption of the contaminant (Sheppard et al.1995). If the contaminant is irreversibly bound to soil particles, the contaminant is unlikely to beabsorbed in the gastrointestinal tract. Hexavalent chromium exists in soils as a relatively soluble anionand may be present in bioavailable form. In contrast, chromium(III) present in soil is generally not verysoluble or mobile under most environmental conditions and is not readily bioavailable (James et al. 1997).Studies discussing the oral absorption of chromium in rats from a soil surface in which 30% of thechromium was in hexavalent form and 70% was in trivalent form suggested that while absorption inanimals is quite low, chromium appeared to be better absorbed from soil than from soluble chromate salts(Witmer et al. 1989, 1991). However, less than half of the administered dose of chromium could beaccounted for in this study, and in separate experiments with low dosages administered to the rats, thecontrol animals actually had higher concentrations of chromium than the animals that were administeredthe oral dose. Children may accidently ingest chromium picolinate in households whose members usethis product as a dietary supplement unless it is well stored and kept away from children. Small amountsof chromium are used in certain consumer products such as toners in copying machines and printers, butchildhood exposure from these sources are expected to be low. Children may also be exposed tochromium from parents’ clothing or items removed from the workplace if the parents are employed in asetting where occupational exposure is significant (see Section 5.5). Chromium has been detected inbreast milk at concentrations of 0.06–1.56 µg/L (Casey and Hambidge 1984), suggesting that childrencould be exposed to chromium from breast-feeding mothers. Studies on mice have shown that chromiumcrosses the placenta and can concentrate in fetal tissue (Danielsson et al. 1982; Saxena et al.1990a).5.7 POPULATIONS WITH POTENTIALLY HIGH EXPOSURESIn addition to individuals who are occupationally exposed to chromium (see Section 5.5), there areseveral groups within the general population that have potentially high exposures (higher thanbackground levels) to chromium. These populations include individuals living in proximity to siteswhere chromium was produced or sites where chromium was disposed, and individuals living near oneof the NPL hazardous waste sites where chromium has been detected in some environmental media(HazDat 2000). Persons using chromium picolinate as a dietary supplement will also be exposed tohigher levels of chromium than those not ingesting this product (Anderson 1998b). Like many otherproducts used to promote weight loss or speed metabolism there is also the potential for overuse of this