Residue Levels of Organochlorine Pesticides in Breast Milk and Its Associations with Cord Blood Thyroid Hormones and the Offspring’s Neurodevelopment

Abstract

Previous studies have demonstrated that organochlorine pesticide (OCP) exposure has a negative impact on the neurological function of infants. Only a few reports have investigated the thyroid and growth hormones and their relationship to neurodevelopment after human exposure to OCPs, especially in the case of infants. Our goal was to determine whether breastmilk OCP residues were associated with negative impacts and/or alterations in the neurodevelopment of infants among specific southern Taiwanese mother–breastfed infant pairs. Our subjects (n = 55 pairs) were recruited from southern Taiwan between 2007 and 2010. The thyroid and growth hormone levels in the cord blood samples collected after childbirth were determined. The breastmilk was gathered within one month after childbirth for the determination of OCP levels using a high-resolution gas chromatograph with mass spectrometry, and the neurodevelopment of 10–12-month-old infants was examined using the Bayley Scales of Infant and Toddler Development®, Third Edition (Bayley-III). It was observed that 4,4′-dichlorodiphenyl-dichloroethylene (4,4′-DDE) (mean = 10.3 ng/g lipid) was the most predominant OCP compound in the breastmilk samples. At higher concentrations (>75th percentile), specific OCPs were associated with significantly lower levels of thyroid and growth hormones than at lower concentrations (<75th percentile). Significantly higher odds ratios (ORs) were observed for binary cognitive (OR = 8.09, p = 0.025 for 4,4′-DDT), language (OR = 11.9, p = 0.013 for 4,4′-DDT) and social–emotional (OR = 6.06, p = 0.01 for trans-CHL) composite scores for specific OCPs belonging to the lower exposure group as compared to the higher OCP exposure group. The five domain Bayley-III infant neurodevelopment outcomes were negatively associated with specific OCPs in the breast milk samples based on the redundancy analysis (RDA) test. Bayley-III scales, which include cognitive, language, motor, social-emotional, and adaptive behavior scales, could be predicted by 4,4′-DDT, endrin, endosulfan I, heptachlor, or heptachlor epoxide using multivariate linear regression models with adjustment for maternal age, pre-pregnant BMI, parity, and infant gender. In conclusion, although our study showed that postnatal exposure to breast milk OCPs may be associated with infant neurodevelopmental outcomes and that prenatal exposure, if extrapolated from breastmilk levels, is associated with changes in thyroid and growth hormones that may have effects on neurodevelopment, these associations are only suggestive; thus, further studies are recommended for confirmation.

Infants' Neurodevelopmental Effects of PM2.5 and Persistent Organohalogen Pollutants Exposure in Southern Taiwan

“…3, high concentration (mean ± SD) of 4,4'-DDE in breast milk were found in both low PM 2.5 exposure areas (10.49 ± 7.83) and high PM 2.5 exposure areas (10.14 ± 7.83). Studies by Chao et al (2006); Chen et al (2018a); Kao et al (2019) also showed similar results proving that 4,4'-DDE is the principal OCP residue that can be found in the breast milk. Elimination of 4,4'-DDE in the body is slower with an estimated half-life of six years as compared to 4,4'-DDT (Noren and Meironyte, 2000).…”

“…Studying subjects gave informed consent after receiving detailed explanations of the study and potential consequences prior to enrollment. Our subjects, the pregnant women, were invited during the routine health check-up in the obstetric clinics of the hospitals in Kaohsiung and Pingtung as described in our previous reports (Chao et al, 2011;Kao et al, 2019). In brief, more than 350 pregnant women were invited and most of them joined our study.…”

“…After collection, the samples were frozen (-4℃) at home and then transferred to the laboratory in National Pingtung University of Science and Technology and kept at -20℃. Extraction and clean-up procedure was done as described in previous studies (Chao et al, 2011;Kao et al, 2019). Fourteen PBDE congeners including 47,99,100,153,154,183,196,197,203,206,207,208, and 209 were analysed by high-resolution gas chromatography (Hewlett-Packard GC 6970; Hewlett-Packard, Palo Alto, CA) coupled with a high-resolution mass spectrometer (Micromass Autospec Ultima, Waters, Milford, MA) using a DB-5HT column (J&W Scientific, Folsom, CA) and splitless injector.…”

Markers of epithelial-mesenchymal transition in an experimental breast cancer model induced by organophosphorous pesticides and estrogen (Review)

“…Interestingly, malathion was classified as ‘probably carcinogenic’ to humans (Group 2A) by the International Agency for Research on Cancer in 2017 ( 18 ). Thereafter, studies have confirmed the increase in risk with OP in several hormonal-mediated cancers, including breast, thyroid, and ovary, suggesting potential cancer risk among women ( 36 – 39 ).…”

Perinatal Exposure to Methoxychlor Affects Reproductive Function and Sexual Behavior in Mice

“…MXC is persistent in the environment ( 1 ) because significant amounts of MXC and deriving metabolites can be measured in human tissues, long after stopping its use ( 2 ). For example, MXC has been found in human tissue samples ( 3 ) and breast milk ( 4 ). It has been demonstrated recently that MXC has the potential to promote the transgenerational inheritance of disease ( 5 ).…”