2,3,7,8-Tetrachlorodibenzo-p-dioxin in maternal breast milk and newborn head circumference

Abstract

Dioxins are known to affect infant growth and neurodevelopment in both humans and animals. In this study, we examined the relationship between neonatal head circumference, which is related to fetal brain development, and the concentration of dioxins in breast milk as an indicator of maternal exposure. A total of 42 milk samples were obtained on the fifth to eighth postpartum day from mothers in Japan exposed to dioxins in the environment. The levels of seven dioxins and 10 furan isomers were measured in each milk sample using an HR-GC/MS system. The relationships between the concentration of each dioxin isomer and newborn size, including head circumference, were then investigated after adjustment for confounding factors. The concentration of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic dioxin isomer, negatively correlated with newborn head circumference, even after adjustment for gestational age, infant sex, parity and other confounding factors. However, there were no significant relationships between the concentration of other dioxin and furan isomers in maternal breast milk and infant height, weight and chest circumference at birth. These facts suggested that fetal brain development might be influenced by maternal exposure to TCDD in the environment.

Prenatal exposure to PCDDs/PCDFs and dioxin-like PCBs in relation to birth weight

“…A previous Finnish study reported that the 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, and 2,3,4,7,8-PeCDF levels in breast milk were negatively correlated with birth weight (Vartiainen et al, 1998). However, another Japanese study reported that there were significant relationships between infant head circumference and 2,3,7,8-TCDD and 2,3,4,7,8-PeCDF levels (Nishijo et al, 2008). We found significantly negative associations between 2,3,4,7,8-PeCDF levels and birth weight after we adjusted for potential confounders.…”

“…Another recent study examining the effects of individual congeners of PCDDs/PCDFs and DL-PCBs on birth weight reported that only OCDD levels in breast milk had a significant negative correlation (Tajimi et al, 2005). However, there were no significant relationships between birth weight and PCDDs/PCDFs congeners in maternal breast milk (Nishijo et al, 2008). Thus, reported results on the relationship between birth weight and the levels of PCDDs/PCDFs and DL-PCBs are currently limited and inconsistent.…”

“…The levels of PCDDs/PCDFs and DL-PCBs in maternal blood during pregnancy more directly evaluate the fetal exposure levels than those levels in breast milk. Our study is the first to report the influence of the levels of PCDDs/PCDFs and DL-PCBs in maternal blood on birth weight, although Vartiainen et al, Tajimi et al and Nishijo et al have studied the effects on birth weight using those levels in breast milk (Vartiainen et al, 1998;Tajimi et al, 2005;Nishijo et al, 2008). We also examined which individual congeners of PCDDs/PCDFs and DL-PCBs have harmful effects on birth weight.…”

“…Because their multiple regression models have not included important potential confounders such as gestational age and infant sex, we could not simply compare between their results and our results. Another Japanese study, which has examined 42 breast milk samples, reported that there were no significant relationships between birth weight and the level of individual PCDDs/PCDFs congeners after adjustments for confounding factors, but significant relationships were shown between infant head circumference and 2,3,7,8-TCDD and 2,3,4,7,8-PeCDF levels (Nishijo et al, 2008). We also examined the influence of PCDDs/PCDFs and DL-PCBs on birth length and head circumference at birth, but there were no significant relationships between these birth outcomes and the levels of PCDDs/PCDFs and DL-PCBs (data not shown), only a significant relationship with birth weight.…”

Dioxin levels in the breast milk and estradiol and androgen levels in the saliva of Vietnamese primiparae

“…Breast milk samples were analyzed following previously reported procedures (Tawara et al 2003;Nishijo et al 2008). The fat content in breast milk was determined using the method described by Patterson et al (1987 Berg et al 2006).…”