Jan Dejmek

Ambient Air Pollution and Pregnancy Outcomes: A Review of the Literature

Over the last decade or so, a large number of studies have investigated the possible adverse effects of ambient air pollution on birth outcomes. We reviewed these studies, which were identified by a systematic search of the main scientific databases. Virtually all reviewed studies were population based, with information on exposure to air pollution derived from routine monitoring sources. Overall, there is evidence implicating air pollution in adverse effects on different birth outcomes, but the strength of the evidence differs between outcomes. The evidence is sufficient to infer a causal relationship between particulate air pollution and respiratory deaths in the postneonatal period. For air pollution and birth weight the evidence suggests causality, but further studies are needed to confirm an effect and its size and to clarify the most vulnerable period of pregnancy and the role of different pollutants. For preterm births and intrauterine growth retardation (IUGR) the evidence as yet is insufficient to infer causality, but the available evidence justifies further studies. Molecular epidemiologic studies suggest possible biologic mechanisms for the effect on birth weight, premature birth, and IUGR and support the view that the relation between pollution and these birth outcomes is genuine. For birth defects, the evidence base so far is insufficient to draw conclusions. In terms of exposure to specific pollutants, particulates seem the most important for infant deaths, and the effect on IUGR seems linked to polycyclic aromatic hydrocarbons, but the existing evidence does not allow precise identification of the different pollutants or the timing of exposure that can result in adverse pregnancy outcomes.

DNA adducts in human placenta as related to air pollution and to GSTM1 genotype

DNA adducts in human placenta have been studied in relation to metabolic genotype for glutathione S-transferase M1 (GSTM1) in 98 mothers living in two regions with a different annual average air pollution levels: Northern Bohemia-the district of Teplice as polluted industrial area (mines, brown coal power plants) and Southern Bohemia-the district of Prachatice as agricultural area without heavy industry. Forty-nine placenta samples (25 from the Teplice district and 24 from the Prachatice district) from non-smoking mothers with the date of delivery in the summer period and 49 placenta samples (25 from the Teplice district and 24 from Prachatice district) from mothers with the date of delivery in the winter period were analysed. The total DNA adduct levels were calculated as the sum of adducts in the diagnoal radioactive zone (DRZ) and one distinct spot outside of the DRZ (termed X), which was detected in almost all placenta samples. We found total DNA adduct levels of 1.40 +/- 0.87 (0.04-3.65) and 1.04 +/- 0.63 (0.11-3.08) adducts per 10(8) nucleotides for the Teplice and Prachatice districts, respectively. The significant difference between both districts in placental DNA adduct levels was found for the winter sampling period only (1.49 vs. 0.96 adducts per 10(8) nucleotides; p = 0.023). No seasonal variation was observed for DNA adduct levels in the overall population studied. A positive GSTM1 genotype was detected in 51 subjects, while GSTM1-null genotype was found in 47 subjects. Higher DNA adduct levels were detected in a group with GSTM1-null genotype (p = 0.009). This finding seems more significant for subjects in the Teplice district (p = 0.047) than for those in the Prachatice district (p = 0.092). Significant district and seasonal differences were found in subgroups carrying the GSTM1-null genotype. DNA adduct levels in placentas of mothers with GSTM1-null genotype living in the polluted district of Teplice were higher than those in Prachatice (p = 0.050); also the adduct levels in placentas sampled in the summer period were higher than those sampled in the winter period (p = 0.011). Our results indicate that simultaneous analysis of DNA adducts and metabolic genotypes could emphasize the use of DNA adduct measurements, particularly in the case of the environmental exposure when the total doses of genotoxic pollutants are very low.

Coal Home Heating and Environmental Tobacco Smoke in Relation to Lower Respiratory Illness in Czech Children, from Birth to 3 Years of Age

Objective The objective of this study was to evaluate how indoor pollution from tobacco and home heating may adversely affect respiratory health in young children. Design A birth cohort was followed longitudinally for 3 years to determine incidence of lower respiratory illness (LRI). Participants A total of 452 children born 1994–1996 in two districts in the Czech Republic participated. Evaluations Indoor combustion exposures were home heating and cooking fuel, mother’s smoking during pregnancy, and other adult smokers in the household. Diagnoses of LRI (primarily acute bronchitis) from birth to 3 years of age were abstracted from pediatric records. Questionnaires completed at delivery and at 3-year follow-up provided covariate information. LRI incidence rates were modeled with generalized linear models adjusting for repeated measures and for numerous potential confounders. Results LRI diagnoses occurred more frequently in children from homes heated by coal [vs. other energy sources or distant furnaces; rate ratio (RR) = 1.45; 95% confidence interval (CI), 1.07–1.97]. Maternal prenatal smoking and other adult smokers also increased LRI rates (respectively: RR = 1.48; 95% CI, 1.10–2.01; and RR = 1.29; 95% CI, 1.01–1.65). Cooking fuels (primarily electricity, natural gas, or propane) were not associated with LRI incidence. For children never breast-fed, coal home heating and mother’s smoking conferred substantially greater risks: RR = 2.77 (95% CI, 1.45–5.27) and RR = 2.52 (95% CI, 1.31–4.85), respectively. Conclusions Maternal smoking and coal home heating increased risk for LRI in the first 3 years of life, particularly in children not breast-fed. Relevance Few studies have described effects of coal heating fuel on children’s health in a Western country. Breast-feeding may attenuate adverse effects of prenatal and childhood exposures to combustion products.

Vitamin C, E and A Levels in Maternal and Fetal Blood for Czech and Gypsy Ethnic Groups in the Czech Republic

Vitamin C, E and A levels in maternal and cord blood sera were examined at delivery in two districts of the Czech Republic. Information on personal and social characteristics, health, ethnicity, and lifestyle was also collected. A highly significant correlation between ascorbate levels in maternal and cord blood was found. Vitamin C levels in cord blood were about 1.7 times those in maternal blood. This ratio was much higher for mothers deficient in vitamin C: it was about 3 for deficient nonsmokers and as high as 5 for deficient mothers who smoked cigarettes (p < 0.01). This finding may suggest a compensatory mechanism in fetuses that are endangered by oxidative stress. The mean maternal blood levels of vitamin A and E were higher than in fetal blood (both p < 0.001). The mean fetal/maternal ratios were 0.7 for vitamin A and 0.2 for vitamin E levels; these ratios were considerably higher for mothers deficient in a particular vitamin as compared with those for well-nourished mothers. Ascorbate levels were associated with maternal education and smoking. Significantly decreased vitamin C levels were observed in Gypsy mothers and their babies; this may be attributed to unfavorable diet and smoking habits: about 78% of Gypsy mothers admitted smoking as compared with 31% of Czech mothers.

New Knowledge about the Impact of Environmental Exposure to PAHs

Organic compounds adsorbed to air particles (PM10) induced DNA adducts and embryotoxicity in in vitro and in vivo studies. Carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) induced 45-50% of all DNA adducts caused by organic matter bound to PM10. Placental bulky DNA adducts were affected by air pollution, smoking, genotypes and vitamin C. Higher DNA adduct levels were observed in nonsmoking mothers delivering children with intrauterine growth retardation (IUGR). An increased risk of IUGR was established in the pregnancy outcome study for mothers exposed to c-PAHs >15 ng/m during the first month of gestation. All these results indicate that c-PAHs represent a very important group of air pollutants.