Ikezuki, 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.

Ikezuki 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.

What 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).

They 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.

What 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.

Ikezuki 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.

from Ikezuki et al. 2003

What 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 increased genital abnormalities in boys, earlier sexual maturation in girls, decreased sperm count in men, and increased breast cancer in women (links added)."