rachel roisman m d m p hrachel roisman, m.d., m.p.h ... · presentation to scientific guidance...
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Rachel Roisman M D M P HRachel Roisman, M.D., M.P.H.California Environmental Contaminant Biomonitoring Program
Office of Environmental Health Hazard Assessment
Presentation to Scientific Guidance Panel December 5, 2008
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Cyclosiloxanes have silicon-oxygen atoms singly bonded in a ring structureCyclosiloxanes in common usage:
D4 D5 D6Octamethylcyclotetra Decamethylcyclopenta DodecamethylcyclohexaOctamethylcyclotetra- Decamethylcyclopenta- Dodecamethylcyclohexa-
Si
OSi
O
Si
O Si
O
OSi
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Widely used for industrial applications and in consumer productsconsumer products(e.g., antiperspirants, hair sprays, skin creams, shaving products, and cosmetics)p , )Annual U.S. import/production volume o 100-500 million pounds (D4, D5)
10 0 ll d ( 6)o 10-50 million pounds (D6)Human exposure occurs via:o Use of personal care and other consumer productso Use of personal care and other consumer productso Environmental exposures
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Horii and Kannan (2008) estimated daily exposure in the U S to cyclosiloxanes fromexposure in the U.S. to cyclosiloxanes from consumer products as: ◦ D4: 1 mg/day◦ D4: 1 mg/day ◦ D5: 233 mg/day ◦ D6: 22 mg/dayD6: 22 mg/day
Indications of long half-lives in humans: elevated levels found in women several years yafter removal of silicone breast implants
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Found in air, soil, sediment, sludge, and waterDetected in fish and other aquatic organisms
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D4o Weak estrogenic effectso Weak estrogenic effects o Benign uterine tumors (adenomas) in ratsD5o Uterine endometrial adenocarcinomas in female rats
o Relevance to humans has been questionedo Effects on neurotransmitter dopamine and hormoneo Effects on neurotransmitter dopamine and hormone
prolactinD6o Liver and thyroid enlargemento Reproductive effect in rats
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Cyclosiloxanes substituted as safer alternatives for a variety of uses◦ Important to know if substitutes for existing
h l l lchemicals are accumulating in people
Concerns regarding persistence and toxicity
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Availability of analytical methodM h d il bl◦ Methods available◦ Contamination, evaporation are potential issues
Ad t bi iAdequate biospecimens◦ Plasma and blood
Incremental cost◦ Equipment available in laboratory◦ Can bundle cyclosiloxanes with each other but not
with other chemicals