Y, O Tsutsumi, Y Takai, Y Kamei and Y Taketani. 2002. Determination
of bisphenol A concentrations in human biological fluids reveals
significant early prenatal exposure. Human
Reproduction 17: 2839–2841.
Virtually all Americans exposed to BPA
Background on BPA
et al. report biologically significant levels of bisphenol
A (BPA) can be found in human amniotic fluid during the first trimester
of pregnancy. Their data add to the weight
of evidence now demonstrating that human fetal exposure
to BPA is widespread and at levels that, based on animal
experiments, creates plausible risks of adverse health effects.
did they do? Ikezuki et al.obtained human blood
samples from a range of sources representing different stages of
pregnancy: 30 healthy, nonpregnant pre-menopausal women; 37 women
in early pregnancy; 37 women in late pregnancy; 32 umbilical cords
at delivery; 37 ovarian follicular fluids (aspirated during IVF
procedures); 32 samples of amniotic fluid via amniocentesis at 15-18
weeks gestation (early pregnancy); and 38 amniotic fluid samples
at full-term Caesarean section (late pregnancy).
analyzed these samples using a novel "enzyme-linked immunosorbent"
assay (ELISA) capable of characterizing BPA concentrations in a
range from 0.5–5000 ng/ml. They also confirmed the accuracy
of this technique by demonstrating that its results were highly
correlated with other measurement techniques.
did they find? They detected biphenol A in all maternal/fetal
stages tested at levels which animal experiments would indicate
are biologically significant, well into the parts per billion range.
et al. found the highest level in amniotic fluid in early
pregnancy (see figure below). They interpret this to indicate that
(1) BPA is entering amniotic fluid from maternal serum and (2) that
enzymes capable of metabolizing BPA are not yet fully activated
in the fetus. As the fetus matures, those enzymes become more effective
and also the amniotic fluid is diluted by fetal urine. This leads
to a reduction of BPA in amniotic fluid during late stages of pregnancy.
Ikezuki et al. 2003 |
does it mean? Ikezuki et al.'s results are very
comparable to a recent German
study, confirming that BPA penetrates the human womb and reaches
the fetus at levels now established to cause effects in animal experiments.
They conclude: "There is much to be elucidated about the involvement
of early BPA exposure in the recent phenomena in humans, such as
abnormalities in boys, earlier
sexual maturation in girls, decreased
sperm count in men, and increased
breast cancer in women (links added.)"