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Abstract
Previous studies from this laboratory have focused on the characterization of blood protein adducts formed in utero as a result of maternal smoking during pregnancy. These biological samples, obtained during the third trimester of pregnancy, at delivery, have clearly shown a correlation between maternal smoking histories and exposure of the fetus to tobacco smoke carcinogens, including 4-aminobiphenyl and benzo(a)pyrene. In the present study, we examined exposure of the fetus during the first trimester of pregnancy to various environmental carcinogens, particularly those found in tobacco smoke. Amniotic fluid samples were obtained from women undergoing routine amniocentesis between 16 and 20 weeks gestational age. Amniotic fluid, produced by the fetal lungs and kidneys, is an important part of pregnancy and fetal development and this fluid surrounds the fetus throughout pregnancy. In these studies, samples of amniotic fluid were obtained from nonsmokers as well as 0.5 pack per day smokers, 1.0 pack per day smokers, and greater than 2.0 pack per day smokers. Maternal smoking status was determined by questionnaire as well as assessment of amniotic fluid for cotinine via immunoassay. Amniotic fluid samples were extracted and analyzed for the presence of polycyclic aromatic hydrocarbons (PAHs). A clear correlation was found between levels of maternal smoking and PAHs in the amniotic fluid. Amniotic fluid 1-hydroxypyrene levels ranged from 1.54 ± 0.12 μ g/L in nonsmokers to 11.72 ± 0.67 μ g/L in women smoking greater than 2 pks/da, indicating approximately a 10X increase over nonsmokers. Similar results were found 3-hydroxybenzo(a)pyrene, 6-hydroxybenzo(a)pyrene, and 3,6-dihydroxybenzo(a)pyrene, metabolites of the carcinogen benzo(a)pyrene as well as with the 9-hydroxy and 9,10-dihydroxy metabolites of anthracene. The 5-hydroxymethyl metabolite of 5-methylchrysene was found to range in concentrations from 1.65 ± 0.11 μ g/L in nonsmokers to 12.67 ± 0.79 μ g/L in greater than 2 packs per day smokers.
These results demonstrate that amniotic fluid can serve as a biological marker of exposure to tobacco related polycyclic aromatic hydrocarbons. Identification of potentially harmful compounds detected at an early stage of pregnancy may prevent subsequent exposures to the fetus and as a result decrease the risk of potential genotoxic as well as teratogenic events.