Health Implications of Perchlorate Ingestion pot

[...]... review of EPA’s findings in its 2002 perchlorate risk assessment focused on four points: the mode -of- action model of perchlorate toxicity, the definition of adverse effect, the point of departure, and the use of uncertainty factors to derive a reference dose (RfD) for daily oral expo- Summary 13 sures to perchlorate EPA’s proposed mode -of- action model of perchlorate toxicity represents a continuum of possible... 2002 Health effects assessment for environmental perchlorate contamination: The dose response for inhibition of thyroidal radioiodide uptake in humans Environ Health Perspect 110:927-937 16 Health Implications of Perchlorate Ingestion recommends using a total uncertainty factor of 10 A full factor of 10 should be used for the intraspecies factor to protect the most sensitive population—the fetuses of. .. the influence of iodide status on the effects of perchlorate The committee recommends a series of in vitro studies using human tissues and animal studies to determine the role of NIS in placental iodide transport, the susceptibility of 5 For comparison, EPA’s draft RfD in its 2002 draft risk assessment was 0.00003 mg/kg per day 18 Health Implications of Perchlorate Ingestion breast NIS to perchlorate. .. data collection is 4 parts per billion (ppb) (4 micrograms per liter [:g/L]) 3 4 Health Implications of Perchlorate Ingestion THE CHARGE TO THE COMMITTEE In response to the agencies’ request, the NRC convened the Committee to Assess the Health Implications of Perchlorate Ingestion, which prepared this report The members of the committee were selected for their expertise in pediatrics; endocrinology;... purpose of EPA’s perchlorate risk assessment was to calculate an RfD The first step in deriving an RfD is a comprehensive review of all relevant human and animal data Traditionally, a critical effect and a critical study are then identified that serve as the point of departure for the 14 Health Implications of Perchlorate Ingestion Serum Perchlorate exposure Perchlorate in blood Inhibition of iodide uptake... (cessation of production of red blood cells) or agranulocytosis (cessation of production of white blood cells), and seven of them died Because of those events and the development of better antithyroid drugs, the use of perchlorate to treat hyperthyroid patients largely ceased by the late 1960s A study of long-term administration of potassium perchlorate reported in 1984, however, provides useful data Eighteen... provide useful information Studies of pregnant monkeys could also provide useful information on the effects of perchlorate on fetal and neonatal development Further toxicology studies of perchlorate in rats would be less useful for clarifying the health effects of perchlorate in humans Especially critical issues in perchlorate risk assessment have been the effect of perchlorate on placental and breast... the association of perchlorate exposure with autism and attentiondeficit-hyperactivity disorder (ADHD) Although the committee considers the inclusion of ADHD plausible, it questions the appropriateness of autism as an end point given that autism has not been observed in the spectrum of 10 Health Implications of Perchlorate Ingestion clinical outcomes in children who had congenital hypothyroidism and... 5-3 Committee's suggested mode -of- action model for perchlorate toxicity in humans, 14 Timeline of perchlorate- related regulatory activities, 21 EPA’s proposed continuum of possible health effects of perchlorate exposure, 28 Diagram of thyroid cells and thyroid follicle, showing key steps in thyroxine (T4) and triiodothyronine (T3) synthesis and secretion, 37 Structures of thyroxine (T4), triiodothyronine... Exposure, 183 Sensitive Populations, 188 Public -Health Implications of Iodide Status, 195 References, 196 APPENDIXES A Biographical Information on the Committee to Assess the Health Implications of Perchlorate Ingestion B Glossary C Participants at Public Sessions D Sensitivity of Perchlorate- Induced Iodide Uptake Inhibition to . class="bi x0 y0 w0 h0" alt="" H ealth Implications of Perchlorate Ingestion Committee to Assess the Health Implications of Perchlorate Ingestion Board on Environmental Studies. Assess the Health Implications of Perchlorate Ingestion xiii Contents SUMMARY 3 1I NTRODUCTION 19 Regulatory History, 20 Characteristics of Perchlorate, 22 Use and Occurrence of Perchlorate, . Committee to Assess the Health Implications of Perchlorate Ingestion reviews the current state of the science regarding potential adverse health effects of perchlorate exposure. Specifically, the committee