Placental transfer of DDT in mother-infant pairs from Northern Thailand

The present study objective was to investigate ratios and correlation coefficients between dichlorodiphenyltrichloroethane (DDT) compounds in cord and maternal sera of mother-infant pairs from northern Thailand. The study site was located in Chiang Dao District of Chiang Mai Province which was an agricultural and former malaria endemic area. DDT compounds were analyzed in 88 cord and maternal serum samples using gas chromatography-electron capture detection (GC-ECD). p,p'-DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene) was the major component and detected in every cord and maternal serum samples with geometric means of 1,255 and 1,793 n g(-1) lipids, respectively. p,p'-DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) was detected at 89.8 and 100% of cord and maternal serum samples, respectively. The second and third highest levels detected were p,p'-DDD (1,1-dichloro-2,2-bis(p-chlorophenyl)ethane) and p,p'-DDT, respectively. The ratios between cord and maternal sera for p,p'-DDE, p,p'-DDT, and p,p'-DDD that were less than 1 had high correlation coefficients (ratio = 0.70, r = 0.82 for p,p'-DDE, ratio = 0.62, r = 0.66 for p,p'-DDT, and ratio = 0.79, r = 0.78 for p,p'-DDD). The high correlation coefficients indicate that cord serum levels of DDT compounds could be accurately estimated from maternal serum levels. It can be concluded that cord serum levels of p,p'-DDE, p,p'-DDT, and p,p'-DDD were approximately 70%, 62%, and 79% of maternal serum levels, respectively. Furthermore, our findings can be applied in public health to monitor and evaluate risk among infants from high DDT exposure area.     

The association between organochlorine and thyroid hormone levels in cord serum: a study from northern Thailand

It is now known that many organochlorines (OCs) act as endocrine disruptors, causing harmful effects on wildlife and humans. Several field and laboratory animal studies have reported that OCs cause adverse effects on thyroid hormone status. However, data regarding their effects on thyroid hormone status in humans are inconclusive. Because a developing fetus is especially sensitive to hormonal disruption by exposure to OCs, the adverse health effects on infants are of concern. The present study aimed to investigate the association between OC levels in maternal and cord serum, and the association between OC and thyroid hormone levels in cord serum. The study was performed with 39 mother-infant pairs from Mae Rim District of Chiang Mai Province, northern Thailand, who had normal delivery and full term gestation. Maternal blood was collected for measuring OCs and total lipids. Umbilical cord blood was collected for measuring OCs, total lipids, and thyroid hormones, including total thyroxine (TT(4)), free thyroxine (FT(4)), and thyroid stimulating hormone (TSH). 1,1-dichloro-2,2-di(4-chlorophenyl)ethylene (p,p'-DDE) had the highest level in all serum samples with a geometric mean of 1,191 ng/g lipids in maternal serum and 742 ng/g lipids in cord serum. The second highest level was that for 1,1,1-trichloro-2,2-di(4-chlorophenyl)ethane (p,p'-DDT), followed by 1,1-dichloro-2,2-di(4-chlorophenyl)ethane (p,p'-DDD). Levels of p,p'-DDE, p,p'-DDT, p,p'-DDD, and dieldrin in maternal serum were positively associated with levels in cord serum (r = 0.86, 0.77, 0.66, and 0.60, respectively; P<0.001). The important findings were that cord serum TT(4) levels were negatively associated with cord serum levels of p,p'-DDE (r = -0.37, P = 0.024), p,p'-DDT.3 (r = -0.33, P = 0.048), and 1,1-dichloro-2-(2-chlorophenyl)-2-(4-chlorophenyl)ethylene (o,p'-DDE) (r = -0.76, P = 0.019). These results therefore suggest that exposure to DDT and its metabolites during fetal development may cause some effects on thyroid hormonal status in infants.     

Placental transfer of DDT in mother-infant pairs from Northern Thailand

The present study objective was to investigate ratios and correlation coefficients between dichlorodiphenyltrichloroethane (DDT) compounds in cord and maternal sera of mother-infant pairs from northern Thailand. The study site was located in Chiang Dao District of Chiang Mai Province which was an agricultural and former malaria endemic area. DDT compounds were analyzed in 88 cord and maternal serum samples using gas chromatography-electron capture detection (GC-ECD). p,p′-DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene) was the major component and detected in every cord and maternal serum samples with geometric means of 1,255 and 1,793 n g^?1 lipids, respectively. p,p′-DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) was detected at 89.8 and 100% of cord and maternal serum samples, respectively. The second and third highest levels detected were p,p′-DDD (1,1-dichloro-2,2-bis(p-chlorophenyl)ethane) and p,p′-DDT, respectively. The ratios between cord and maternal sera for p,p′-DDE, p,p′-DDT, and p,p′-DDD that were less than 1 had high correlation coefficients (ratio = 0.70, r = 0.82 for p,p′-DDE, ratio = 0.62, r = 0.66 for p,p′-DDT, and ratio = 0.79, r = 0.78 for p,p′-DDD). The high correlation coefficients indicate that cord serum levels of DDT compounds could be accurately estimated from maternal serum levels. It can be concluded that cord serum levels of p,p′-DDE, p,p′-DDT, and p,p′-DDD were approximately 70%, 62%, and 79% of maternal serum levels, respectively. Furthermore, our findings can be applied in public health to monitor and evaluate risk among infants from high DDT exposure area.