Maternal Exposure to Certain Chemicals May Put Children at Risk for Asthma Development

A recent study shows a potential association between exposure to everyday chemicals during pregnancy and the development of asthma in children whose mothers were exposed. The authors note that the findings can serve as a valuable foundation when creating recommendations on prenatal exposure.^1,2

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Phenols, such as parabens and alkylphenols, are widely used in consumer products for their preservative and antimicrobial properties. Although use is considered safe in small amounts, experts noted concerns about their potential long-term health effects as endocrine disruptors. The investigators hypothesized that these everyday chemicals may lead to an increase in allergenic diseases, such as asthma, during sensitive periods (eg, pregnancy).^1,2

For this research, the investigators analyzed the associations between maternal urinary phenol concentrations during early pregnancy and the development of asthma in children at the age of 4 years. Data were used from the Japan Environment and Children’s Study (JECS), which was a large-scale nationwide birth cohort study. A total of 3515 pairs of mothers and children who were born at term (pregnancy period: ≥37 weeks) were randomly recruited from 15 regional health centers in Japan.²

Additionally, 24 substances—including nitrophenols, bisphenols, carvacrol, and thymol—were examined in the women’s urine samples. Presence or development of asthma were assessed in children when they reached 4 years of age. The investigators also extracted data which were collected prior to and after birth, which included pregnancy period, birth weight, gender of the child, age of the mother, maternal and paternal smoking during pregnancy, and maternal history of asthma.²

According to the findings, high levels of butylparaben—a chemical often found in personal care products such as shampoos and lotions—during early pregnancy were associated with a 1.54-fold increase (95% CI: 1.11–2.15) in the odds of asthma development in children when assessed at 4 years. Additionally, asthma development odds were observed to be higher in male children (2.09 [95% CI: 1.20–3.65]) compared with females (0.65 [95% CI: 0.25–1.70]). This finding was noticeable in mothers who were exposed to 4-nonylphenol, which is a chemical found in certain cleaning products and plastics. The authors noted that although many of the other phenols were detected in a small number of participants, further large-scale analyses will be needed to clarify the effects of each sex on phenol exposure.²

Further, the urinary levels of these examined phenols varied differently among the examined women, but methylparaben was detected at high levels (267.7 ng/ml, standard deviation 433.78) in nearly all maternal participants. One positive the authors noted was that 146 participants in the study had nonylphenol levels above the measured sensitivity, which suggests that the current imposed guideline restrictions are effective. Recent research suggests that this chemical could affect immune function, but few studies have reported on the actual effects on the immune mechanisms, such as allergies in humans and information on chronic health effects.²

The authors suggested that future studies should also consider covariates associated with asthma (eg, living environments and personal preferences) because they may be correlated with maternal phenol exposure and asthma development in their children. Additionally, phenol measurements should also be obtained from the children to determine what associations may be present there.²

“These results emphasize the need for careful evaluation of chemical exposure during pregnancy,” said study author Shohei Kuraoka, MD, Department of Pediatrics at Kumamoto University, Southern Kyushu and Okinawa Unit Center of Japan Environment and Children’s Study, in a news release. “Understanding these risks allows us to develop better guidelines to protect maternal and child health.”¹

REFERENCES

1. Kumamoto University. High exposure to everyday chemicals linked to asthma risk in children. News release. November 18, 2024. Accessed November 27, 2024. https://www.eurekalert.org/news-releases/1065344

2. Kuraoka S, Oda M, Ohba T, et al. Association of phenol exposure during pregnancy and asthma development in children: The Japan Environment and Children's study. Environmental Pollution. 2024;361:124801. doi:10.1016/j.envpol.2024.124801Top of FormBottom of Form