| Organochlorine pesticides(OCPs) are broad-spectrum insecticides that possess high efficiency, low toxicity, low cost and convenient to use. Although the production and use of OCPs have been banned in the past thirty years, many studies still reported that OCPs could be detected not only in water, air, soil, sediment, foods, but also in the human biological specimens such as blood, adipose tissue, and breast milk of the general population in China. The properties of OCPs including persistence, lipophilicity and bioaccumulation had enabled them to be bioaccumulated and biomagnificated through the food chain and finally entered into animal and human body, which had serious effects on ecosystems and human health. Not only did animal experiments indicate that OCPs had carcinogenicity, reproductive toxicity and immunotoxicity, but also epidemiology studies confirmed that the accumulation of OCPs in human body had adverse impacts on human health including immunotoxicity, endocrine disorders, reproductive abnormality, nervous system toxicity, birth defect, eventually cancer. In this study, we combined the laboratory detection with the epidemiological data to evaluate related impact factors of OCPs levels in umbilical cord blood, and to assess the association of OCPs exposure with birth weight and birth length of newborn. Furthermore, we also investigated the potential impact of exposure to OCPs on thyroid hormone levels in umbilical cord blood, and provide more scientific evidences for the impact mechanism of OCPs exposure to newborn birth quality.The study consists of the following two parts:Part I: Study on the association between exposure to organochlorine pesticides in umbilical cord blood and newborn birth qualityObjective: To comprehensively evaluate related impact factors of OCPs levels in umbilical cord blood from Huaihe River Basin with serious water pollution based on the previous research works, and assessed the association of OCPs exposure with birth weight and birth length of newborn.Methods: The study was conducted between November 2013 to June 2014 and a total of 1000 pregnant women was enrolled from the local hospital of Huaihe River Basin with typical water pollution. Concentrations of 17 OCPs in umbilical cord blood were detected using gas chromatography/mass spectrometry and the epidemiological data was collected. We evaluate related impact factors of OCPs levels in umbilical cord blood and the association between exposure to OCPs and birth quality by multiple linear regression model.Results: Multiple linear regression analysis of the five main OCPs with > 50% detection frequency indicated that the concentration of ρ,ρ’-DDE in cord blood was significantly and positively correlated with fish consumption and education level of the pregnant women(education level β = 0.025, fish β = 0.015), while the association between ρ,ρ’-DDE level and parity was found to be negative(β =- 0.038). ρ,ρ’-DDT level was significantly and positively correlated with bean products(β = 0.038) and red meat(β = 0.053). Aldrin level was correlated significantly and positively with education level of the pregnant women(β = 0.06) and monthly household income(β = 0.030), and negatively with poultry(β =- 0.048) and pickle(β =- 0.045). Dieldrin and methoxychlor concentrations were significantly positively correlated with education level of the pregnant women(β = 0.078) and red meat(β = 0.116), respectively. Meanwhile, we also found that concentrations of ρ,ρ’-DDE, ρ,ρ’-DDT and aldrin were positively correlated with birth weight(ρ,ρ’-DDE β = 4.103;ρ,ρ’-DDT β = 0.744;aldrin β = 0.307), while dieldrin and methoxychlor were negatively with birth weight(dieldrin β =- 2.209; methoxychlor β =- 12.403), but there were no statistically significant differences(P > 0.05). We found no association between OCPs exposure and newborn birth length.Conclusions: Our results suggested that education level of the pregnant women, monthly household income, parity and dietary habit(red meat, fish, poultry, bean products, pickle) had the potential impact on the level of OCPs in umbilical cord blood. Besides, we found potential association between exposure to OCPs in umbilical cord blood and birth weight, but there was no statistically significant differences. There was no association between OCPs exposure and newborn birth length.Part II: Study on the association between exposure to organochlorine pesticides in umbilical cord blood and thyroid hormone levelsObjective: Thyroid hormone is important to promote the growth and development of fetus. We performed this study to evaluate the association between exposure to OCPs and thyroid hormone levels and to further provide evidences for the impact mechanism of OCPs exposure to newborn birth quality.Methods: We further detected thyroid hormone levels including FT3, FT4 and TSH in umbilical cord blood among 115 pregnant women of Part I, and assessed the potential impact of exposure to OCPs on thyroid hormone levels in umbilical cord blood by logistics regression model.Results: We found that concentrations of OCPs in umbilical cord blood had no significant effect on the levels of FT3 and TSH after adjusting confounding factors(the age of pregnant women, education level, monthly household income, parity, the sex of neonates). However, the concentration of ρ,ρ’-DDE significantly decreased FT4 level(OR = 0.737,95% CI 0.561- 0.968).Conclusions: Our findings suggested that exposure to ρ,ρ’-DDE in utero had the potential impact on thyroid hormone levels, especially FT4 level, but there was no association between exposure to OCPs and TSH level. |
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