Exposure to common phenols during pregnancy associated with asthma development in children
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Key takeaways:
- Children of mothers exposed to high amounts of butylparaben experienced greater risk for asthma.
- Maternal exposure to 4-nonylphenol led to a higher risk for asthma in boys vs. girls.
Children exposed to certain phenols early in utero appeared more likely to develop asthma when born, according to study results published in Environmental Pollution.
The findings provide valuable background for recommendations about prenatal phenol exposure, the researchers concluded.
‘Global concerns’
Phenols are commonly used in consumer products, such as cleaning solutions and cosmetics, according to a press release. Although they are generally considered safe in small amounts, some phenols may act as endocrine disruptors, leading to the development of allergy-related asthma.
“We conducted this study in response to global concerns about phenol, an endocrine disruptor, and its potential association with the recent rise in allergic disease,” Shohei Kuraoka, MD, PhD, of the South Kyushu Okinawa Unit Center, Faculty of Life Sciences, Kumamoto University in Japan, told Healio. “Previous studies on phenol exposure and allergy during pregnancy have been limited, focusing on a narrow range of phenols and analyzing modest sample sizes. The objective of our study was to provide a more comprehensive assessment by measuring a broader spectrum of phenols in a larger cohort of participants.”
Researchers examined the association between maternal urinary phenol concentrations during early pregnancy and the development of asthma in children at age 4 years.
They analyzed data from 3,513 mother-and-child pairs (mean age mothers, 31.6 years; 51% boys) enrolled in a sub-cohort study of the large-scale, nationwide Japan Environment and Children’s Study.
Researchers collected urine samples during the first trimester (mean, 16 weeks’ gestation) and measured samples for concentrations of 24 substances, including nitrophenol, parabens, bisphenol, octylphenol and nonylphenol.
They additionally analyzed responses from asthma development questionnaires distributed to mothers during medical examinations when children turned 4 years old.
Chemical exposure
Results showed that most urine samples included high mean values of methylparaben, ethylparaben and propylparaben.
Specifically, researchers observed a mean value of methylparaben of 267.7 ng/mL (standard deviation, 433.78) and a maximum value of 7,400 ng/mL.
Results also showed a correlation coefficient for 4-nitrophenol and 3-methyl-4-nitrophenol of 0.61, and a correlation coefficient of 0.53 for isopropylparaben (isoPrP) and isobutylparaben.
After adjusting for gender, birth information, parents’ smoking history and maternal asthma complications, researchers found that the maternal group with the top 10% of butylparaben (nBuP) in their urine ( 7.1 ng/mL) had increased risk for child asthma development compared with those with lower nBuP levels (OR = 1.54; 95% CI, 1.11-2.15).
They additionally observed asthma rates greater than 1% for samples with isoPrP, nBuP, 4-t-octylphenol, 4-nonylphenol (4NP), triclocarban and bisphenol S (BPS) compared with samples that did not include these phenols.
Further, mothers with greater levels of isoPrP (OR = 1.43; 95% CI, 0.97–2.11) and BPS (OR = 1.28; 95% CI, 0.93-1.77) in their urine experienced an increased risk for asthma development in their children compared with those with lower phenol levels.
By sex, 13.1% of boys (n = 1,790) and 9.6% of girls (n = 1,723) had asthma. Odds ratios for developing asthma among samples with 4NP included 2.09 (95% CI, 1.2-3.65) for boys and 0.65 (95% CI, 0.25-1.7) for girls (P = .037).
Researchers noted several limitations of the study, including their inability to confirm urinary phenol levels after the first trimester and that the analysis was limited to one country.
“We confirmed that high exposure to butylparaben is clearly associated with asthma development,” Kuraoka told Healio. “The findings that a widely used chemical substance, not only in Japan but globally, may contribute to childhood allergies holds significant implications for managing chemical exposure in the future. I was somewhat surprised by the apparent gender differences observed in the case of nonylphenol.”
Future research
“These findings suggest that more factors and chemicals than previously recognized could affect fetal and childhood development through prenatal exposure, even if there appears to be no direct impact on the mother herself,” Kuraoka told Healio. “Additionally, we need to analyze how mothers with detectable [4NP] or high levels of [nBuP] were exposed to these substances.”
Reference:
- High exposure to everyday chemicals linked to asthma risk in children. https://www.sciencedaily.com/releases/2024/11/241119134328.htm. Published Nov. 18, 2024. Accessed Dec. 9, 2024.
For more information:
Shohei Kuraoka, MD, PhD, can be reached at skuraoka@kuh.kumamoto-u.ac.jp.