7 research outputs found
Direct Measurement of Perchlorate Exposure Biomarkers in a Highly Exposed Population: A Pilot Study
Exposure to perchlorate is ubiquitous in the United States and has been found to
be widespread in food and drinking water. People living in the lower Colorado
River region may have perchlorate exposure because of perchlorate in ground
water and locally-grown produce. Relatively high doses of perchlorate can
inhibit iodine uptake and impair thyroid function, and thus could impair
neurological development in utero. We examined human exposures to perchlorate in
the Imperial Valley among individuals consuming locally grown produce and
compared perchlorate exposure doses to state and federal reference doses. We
collected 24-hour urine specimen from a convenience sample of 31 individuals and
measured urinary excretion rates of perchlorate, thiocyanate, nitrate, and
iodide. In addition, drinking water and local produce were also sampled for
perchlorate. All but two of the water samples tested negative for perchlorate.
Perchlorate levels in 79 produce samples ranged from non-detect to 1816 ppb.
Estimated perchlorate doses ranged from 0.02 to 0.51 µg/kg of body
weight/day. Perchlorate dose increased with the number of servings of dairy
products consumed and with estimated perchlorate levels in produce consumed. The
geometric mean perchlorate dose was 70% higher than for the NHANES
reference population. Our sample of 31 Imperial Valley residents had higher
perchlorate dose levels compared with national reference ranges. Although none
of our exposure estimates exceeded the U. S. EPA reference dose, three
participants exceeded the acceptable daily dose as defined by bench mark dose
methods used by the California Office of Environmental Health Hazard
Assessment
Mercury Toxicity and Contamination of Households from the Use of Skin Creams Adulterated with Mercurous Chloride (Calomel)
Inorganic mercury, in the form of mercurous chloride, or calomel, is intentionally added to some cosmetic products sold through informal channels in Mexico and the US for skin lightening and acne treatment. These products have led to multiple cases of mercury poisoning but few investigations have addressed the contamination of cream users’ homes. We report on several cases of mercury poisoning among three Mexican-American families in California from use of mercury-containing skin creams. Each case resulted in widespread household contamination and secondary contamination of family members. Urine mercury levels in cream users ranged from 37 to 482 µg/g creatinine and in non-users from non-detectable to 107 µg/g creatinine. Air concentrations of up to 8 µg/m3 of mercury within homes exceeded the USEPA/ATSDR health-based guidance and action level of <1.0 μg/m3. Mercury contamination of cream users’ homes presented a multi-pathway exposure environment to residents. Homes required extensive decontamination, including disposal of most household items, to achieve acceptable air levels. The acceptable air levels used were not designed to consider multi-pathway exposure scenarios. These findings support that the calomel is able to change valence form to elemental mercury and volatilize once exposed to the skin or surfaces in the indoor environment
Geometric mean perchlorate dose in urine (µg/kg of body weight/day) and 95% confidence intervals in study participants by total dairy servings, Imperial County, California, 2009.
<p>Geometric mean perchlorate dose in urine (µg/kg of body
weight/day) and 95% confidence intervals in study participants by
total dairy servings, Imperial County, California, 2009.</p
Participant Characteristics, Imperial County, 2009.
<p>Participant Characteristics, Imperial County, 2009.</p