Persistent Environmental Toxicants in Breast Milk and Rapid Infant Growth

Abstract

Background/Aims: Many environmental toxicants are passed to infants in utero and through breast milk. Exposure to toxicants during the perinatal period can alter growth patterns, impairing growth or increasing obesity risk. Previous studies have focused on only a few toxicants at a time, which may confound results. We investigated levels of 26 toxicants in breast milk and their associations with rapid infant growth, a risk factor for later obesity. Methods: We used data from the Norwegian HUMIS study, a multi-center cohort of 2,606 mothers and newborns enrolled between 2002 and 2008. Milk samples collected 1 month after delivery from a subset of 789 women oversampled by overweight were analyzed for toxicants including polychlorinated biphenyls (PCBs), heavy metals, and pesticides. Growth was defined as change in weight-for-age z-score between 0 and 6 months among the HUMIS population, and rapid growth was defined as change in z-score above 0.67. We used a Bayesian variable selection method to determine the exposures that most explained variation in the outcome. Identified toxicants were included in logistic and linear regression models to estimate associations with growth, adjusting for maternal age, smoking, education, pre-pregnancy body mass index (BMI), gestational weight gain, parity, child sex, cumulative breastfeeding, birth weight, gestational age, and preterm status. Results: Of 789 infants, 19.2% displayed rapid growth. The median maternal age was 29.6 years, and the median pre-pregnancy BMI was 24.0 kg/m², with 45.3% of mothers overweight or obese. Rapid growers were more likely to be firstborn. Hexachlorobenzene, β-hexachlorocyclohexane (β-HCH), and PCB-74 were identified in the variable selection method. An interquartile range (IQR) increase in β-HCH exposure was associated with a lower odds of rapid growth (OR 0.63, 95% CI 0.42-0.94). Newborns exposed to high levels of β-HCH showed reduced infant growth (β = -0.03, 95% CI -0.05 to -0.01 for IQR increase in breast milk concentration). No other significant associations were found. Conclusions: Our results suggest that early life β-HCH exposure may be linked to slowed growth. Further research is warranted on the potential mechanism behind this association and the longer-term metabolic effects of perinatal β-HCH exposure.

Infant Dietary Exposures to Environmental Chemicals and Infant/Child Health: A Critical Assessment of the Literature

“…Fifteen studies examined growth in infants and children using various metrics and covering age ranges from newborn infants to children 18 y of age. Chemicals studied included polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and/or PCBs (Criswell et al. 2017; Gladen et al.…”

“…2014), polybrominated diphenyl ethers (PBDEs) (Wohlfahrt-Veje et al. 2014), and organochlorine pesticides, including DDT, dichlorodiphenyldichloroethylene (DDE), hexachlorobenzene (HCB), aldrin, heptachlor, β-hexachlorocyclohexane (β-HCH), α-HCH, and heptachlor epoxide (Criswell et al. 2017; Du et al.…”

“…Criswell et al. (2017) reported an association between increased levels of β-HCH in breast milk and a lower odds of rapid growth between the ages of 0 and 6 mo when their model was adjusted for maternal age, smoking, education, prepregnancy BMI, gestational weight gain, parity, child sex, cumulative breastfeeding, birth weight, gestational age, and preterm status; adjusted models revealed no significant associations between infant growth and exposure to HCB or PCB 74. Jackson et al.…”

“…Criswell et al. (2017) reported an association between breast milk β-HCH levels and infant growth rate but did not evaluate head circumference. Yalçin et al.…”

Lactational programming of glucose homeostasis: a window of opportunity

“…When considering the impact of polychlorinated biphenyls (PCBs), trends found between human breast milk PCB concentrations and infant growth outcomes are conflicting. One study showed a correlation between increased breast milk levels of beta-hexachlorocyclohexane (β-HCH), an agricultural pesticide, at 1 month after birth and reduced infant weight gain up to age 6 months (Criswell et al 2017). However, another found no significant difference between infant growth measures at 6 months and 1 year and increased PCBs in human milk at 3 months postpartum (Pan et al 2010).…”