Risks of Birth Defects Following In Utero Exposures to Unregulated Brominated Haloacetic Acids.

Area of Science:

• Environmental Health
• Toxicology
• Epidemiology

Background:

• Haloacetic acids (HAAs) are regulated disinfection byproducts in drinking water.
• Two brominated HAAs (BrHAAs) are linked to birth defects, but four others are understudied.
• This study focuses on the health impacts of these four unregulated BrHAAs.

Purpose of the Study:

• To investigate the association between prenatal exposure to four unregulated brominated haloacetic acids (BrHAAs) and 16 birth defect phenotypes.
• To assess the relationship between exposure to the sum of six BrHAAs (HAA6) and birth defects.
• To provide epidemiological data on understudied BrHAAs and their potential teratogenicity.

Main Methods:

• Registry-based case-control study design.
• Analysis of 16 birth defect phenotypes in relation to first-trimester BrHAA exposures.
• 1:10 case-to-control matching by conception week and conditional logistic regression.

Main Results:

• Elevated odds ratios observed for specific BrHAAs and certain birth defects, including cleft palate (BDCAA) and obstructive genitourinary defects (CDBAA).
• Reduced odds ratios noted for hypospadias in relation to BCAA exposure.
• Many other associations were near the null or lacked statistical precision.

Conclusions:

• The findings suggest potential associations between specific unregulated BrHAAs and birth defects, meriting further investigation.
• This is the first epidemiological study to examine most of these exposure-outcome relationships.
• Future research should include longer study periods and direct exposure assessments in high-bromide areas.