Impact Of Prenatal Lead, Cadmium And Pyrethroid Exposure On Development Of Offspring

[Backgrounds]There is growing concern about the potential health effects of exposure to various environmental chemicals during pregnancy and infancy. Evidence suggests that fetuses and children are more sensitive than adults to the toxicity of many environmental chemical pollutants because of their higher cell proliferation rates, lower immunologic competence, and decreased ability to detoxify carcinogens and to repair DNA damage. We are conducting a prospective cohort study among pregnant women and newborns to examine the effects of prenatal exposure to these common toxicants on infant growth and early neurodevelopment. The study recruited 1149 mother- baby pairs delivered in the Hospital for Gynecology and Obstetrics of Sheyang County, Jiangsu Province from June 2009 to January 2010. As a part of research project, this paper is principally concerned with effects of heavy metals such as lead and cadmium, and pyrethroid pesticides.[Objectives]1,To evaluate the levels and characteristic of lead, cadmium in umbilical cord blood and pyrethroid pesticides in maternal urine;2,To acquire the profile of physical and mental development of local neonates and 1 year old infants;3,To investigate the impact of prenatal lead, cadmium and pyrethroid exposure on physical and mental development of neonates and 1 year old infants and provide clues to improve local child health care.[Methods]1. Personal interview:A 30-min questionnaire was administered by a trained interviewer after delivery. The questionnaire elicited demographic information, occupational history, residential history, medication information, history of active and passive smoking, alcohol use and pesticide use during pregnancy. Socioeconomic information related to income and education was also collected.2. Biologic sample collection and analysis:Maternal spot urin and umbilical cord blood were collected. We assessed exposure to heavy metals by the cord blood lead and cadmium measurements, and exposure to pyrethroid pesticides by the three urinary metabolites of pyrethroid measurements (3-PBA, cis-DCCA and trans-DCCA).3. Measures relevant to birth outcomes and physical development:Birth weight, birth length, and head circumference were measured immediately after parturition. Information included date of delivery; gestational age at birth, infant sex, APGAR score and malformations were also recorded.4. Follow-up study:After the newborns reached 12 months of age, they were invited to participate in the survey; their weight, height, head circumference and breast circumference were measured as indicators of physical development. Mental development in infancy and early childhood were evaluated using the DST scale.5. Statistical analysis:Epidata 3.1 software was used for the import of data, and SPSS 17.0 software was applied for Statistical analysis. Measures of lead, cadmium and pyrethroid were In-transformed to normalize the distribution and stabilize the variance. The Student's t-test was used to compare the maternal and cord blood chemical levels in different groups. We used multiple linear regression to analyze the association between lead, cadmium, pyrethroid level and birth outcomes or child development, adjusting for potential confounders.[Results]A total of 1,149 pregnant women who gave birth at local maternity hospital took part in this investigation and 620 one year old infants in followed-up study.1,Of the 1,149 pregnant women,77.0% were under 25 years old; 87.4% of their educational level were no more than middle school; 65.0% of them lived in countryside or rural area and 57.3% participated in physical labor before or during pregnancy; 83.4% of them family annual income was below 50,000 yuan; Close to half (45.5%) of women self-reported that they or their household member had applied commercially available indoor insecticides during pregnancy;2,The prevalence of birth defects in our study was 6.0 per 1000 births, low-weight was 0.9% and premature infants was 0.4%; Which were all below the national average level; physical development level of newborns and one year infants were normal, whereas,7.1% and 3.4% of them had low scores in developmental quotient and mental index respectively;3,Significantly negative correlations were found between cord blood cadmiuneexposure and physical development of neonates and infants; Generally, elevated cord blood cadmium levels were significantly associated with decreased birth weight and reduced length, but not with head circumference and breast circumference; Whereas, no sifnificant correlations were found between cord blood lead level and fetus development and later infant development. The results aboved were verified by multiple linear regression analysis;5,Three pyrethroid metabolites were detected synchronously in spot urin samples from 94.1% of mothers with median unadjusted (μg/L) and creatinine-adjusted (μg/g Cre.) were 1.01 and 1.55 for 3-PBA,0.44 and 0.69 for cis-DCCA,1.17 and 1.86 for trans-DCCA respectively. The median values of urinary metabolites in our study were about 4 to 10 times higher as those of general population from the developed countries. Single factor variance analysis showed that pyrethroid metabolites level in maternal urine samples may be affected by educational level, career and the usage condition of indoor pesticide;6,Interestingly, we found there was a temporal season variation tendency in different months. Especially the levels of urinary metabolites in summer were significant higher than those in winter;7,Covariance analysis showed with the increasing of urine pyrethroid metabolites level, the infant's performance score of DST scale decreased,which suggested that prenatal pyrethroid exposure may associated with poor mental development of infant.[Conclusions]Our research suggested that:1,There was a significant association between elevated cord blood cadmium with reduced physical growth of newborns and one year old infants;2,There were high detectable rate and levels of pyrethroid metabolites in pregnant women's urine sample in this population;3,Exposure to elevated levels of pyrethroid pesticides was associated with reduced infant's mental development in this population.