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

Abstract

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.

Keywords:

• Dichlorodiphenyltrichloroethane (DDT)
• organochlorines
• cord serum
• maternal serum
• Northern Thailand

Acknowledgments

This study was funded to RS by Royal Golden Jubilee PhD program, The Thailand Research Fund (PHD/0108/2545). We thank all pregnant participants for their co-operations. We are indebted to Assoc. Prof. Dr. Prasak Thavornyutikarn for his invaluable advice, officers of health centers and hospitals in Chiang Dao District for their kind assistance in subject enrollment and sample collection.

Notes

^a Mean values of parameters between cord and maternal serum were significantly different (P < 0.05), GM : geometric mean; AR : arithmetic mean, SD : standard deviation, Min : minimum, Max : maximum.

** P < 0.01.

*** P < 0.001.

^a Total DDT = p,p′ -DDE + p,p′ -DDT + p,p′ -DDD + o,p′ -DDE + o,p′ -DDT.

^b An agricultural and former malaria endemic area.

^c Non-agricultural and non-former malaria endemic area.