Monograph on the Potential Human Reproductive and ... - OEHHA

nTp brief
ing.sources.of.exposure.(Table.1)..No.biomonitoring.data,.i.e.,.blood.or.urine.concentration.of.
bisphenol.A,.are.available.for.these.life.stages.
[reviewed.in (2)]..An.estimated.daily.intake.of.~1.
µg/kg.bw/day.for.both.breast-fed.and.formulafed.infants.was.calculated.by.the.CERHR.Expert.
Panel.for.Bisphenol.A.(2)..Higher.“worst.case”.
daily.intake.estimates.of.11.–.13.µg/kg.bw/day.
during.the.first.year.of.life.have.been.calculated.
for.infants.(25)..In.children.1.5.to.6.years.of.age,.
the.range.of.estimated.daily.intakes.based.on.
aggregating.sources.of.exposure.is.0.043.–.14.7.
µg/kg.bw/day,.with.14.7.µg/kg.bw/day.representing.a.worst.case.scenario.(27,
29).
Although.biomonitoring.data.are.not.available.
for.infants.and.children.less.than.6.years.of.age,.
blood.and.urine.levels.of.free.bisphenol.A.are.
predicted.to.be.higher.in.these.age.groups.compared.to.pregnant.women.or.other.adult.populations..This.is.based.on.information.related.to.age-specific.differences.in.daily.intake.of.bisphenol.A.and.in.the.ability.to.metabolize.the.chemical..More.specifically,.it.is.based.on.observations.of.(1).higher.urinary.measurements.
of.total.bisphenol.A.in.children.(6.–.11.years.of.
age).compared.to.adolescents.and.adults.(8),.(2).
higher.estimated.daily.intakes.of.bisphenol.A.
for.infants.and.children.(2, 25, 27).compared.
to.estimated.daily.intakes.for.adults.(2, 25, 35),.
and.(3).predicted.higher.blood.concentrations.of.
free.bisphenol.A.in.infants.compared.to.adults.
at.a.given.daily.intake.level.based.on.less.efficient.metabolism.of.bisphenol.A.in.rat.fetuses.
and.neonates.(18 – 20),.and.very.low.or.absent.
activities.in.human.fetuses.and.premature.or.
full-term.infants.of.the.isozymes.that.govern.
glucuronidation.(246 – 248).
adults and children aged
6 years and above
Daily.intake.estimates.for.adults.and.children.
aged.6.years.and.older.are.based.on.(1).back.calculations.from.the.most.recent.CDC.NHANES.
35
data.on.urinary.concentrations.of.total.bisphenol.
and.(2).aggregating.sources.of.exposure.(Table.
1.and.Table.3)..Of.these.estimates,.the.NTP.has.
more.confidence.in.the.estimates.based.on.back.
calculating. from. urinary. biomonitoring. data.
because.all.sources.of.exposure.are.integrated.
into.the.fluid.measurement.and.thus.do.not.have.
to.be.identified.in.advance..However,.it.is.worth.
noting.that.the.estimates.for.non-occupationally.
exposed.adults.based.on.aggregating.sources.
of. exposure. encompass. the. range. estimated.
from.back.calculating.from.urine.[aggregating.
sources.of.exposure:.0.008.–.1.5.µg/kg.bw/day.
(Table.1);.and.back.calculating.based.on.urine:.
0.233.–.0.289.µg/kg.bw/day.for.various.categories.of.adults.ages.20+.at.the.95th.percentile.
(35)]..Fewer.studies.have.estimated.daily.intakes.
for.children.older.than.6.years.of.age.and.adolescents..In.Japanese.children.and.adolescents.
between.the.ages.of.7.and.19.years,.the.range.
of.estimated.daily.intakes.based.on.aggregating.
sources.of.exposure.is.0.36.to.0.55.µg/kg.bw/day.
(30),.which.is.only.slightly.higher.than.the.estimated.range.of.daily.intakes.for.American.children.and.adolescents.based.on.back.calculating.
from.urinary.concentration.of.total.bisphenol.A.
[0.311.–.0.348.µg/kg.bw/day.for.children.ages.
6.–.11.and.12.–.19.at.the.95th.percentile.(35)].
Estimated daily intake based
on blood biomonitoring
The.NTP.also.considered.the.appropriateness.of.
estimating.daily.intake.based.on.back.calculations.from.free.bisphenol.A.measured.in.human.blood.and.concluded.that.the.scientific.uncertainties.are.currently.too.large.to.support.this.
exercise.(see.Appendix.A)..In.brief,.estimated.
daily.intakes.in.adults.based.on.this.approach.
are.much.greater.(~500.µg/kg.–.1.54.mg/kg.bw/
day.for.a.65.kg.human).(3, 249).than.estimates.
of.daily.intake.based.on.aggregating.routes.of.
exposure.(0.008.–.1.5.µg/kg.bw/day).(25, 31).or.
from.back.calculating.from.urinary.data.(adults.
aged.20.–.60.+:.medians.0.0563.–.0.0334.µg/kg.