Nitrate in Drinking Water Linked to Preterm Birth Risks

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A new study published in PLOS Water suggests that even low levels of nitrate, a common agricultural pollutant found in drinking water, may increase the risk of preterm birth and low birth weight in infants. The research highlights concerns about nitrate contamination, primarily from agricultural runoff, and its impact on maternal and infant health.

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Nitrate, a naturally occurring compound essential for plants and animals, has become more prevalent in the environment due to its use in fertilizers. When ingested through contaminated drinking water, nitrate can disrupt the blood’s ability to carry oxygen, potentially affecting fetal development.

“There’s no safe level of prenatal nitrate exposure,” said Jason Semprini, an assistant professor of public health economics at Des Moines University and the study’s lead author.

The study analyzed 357,741 birth records in Iowa from 1970 to 1988, linking them to county-level nitrate measurements taken within 30 days of conception. Findings showed that nitrate levels in drinking water rose about 8% annually during this period. Even at just 0.1 milligrams per liter—1% of the EPA’s current limit—early prenatal exposure was associated with a higher risk of preterm birth. At 5 milligrams per liter (half the EPA’s threshold), there was an increased chance of low birth weight.

Interestingly, the study found no additional risks at nitrate levels above the EPA’s 1992 standard, which remains unchanged despite rising nitrate levels in groundwater nationwide. Semprini noted that while the study focused on Iowa, broader data could strengthen these findings and urged a reevaluation of federal water safety standards.

“Current regulations may not sufficiently protect mothers and their babies from nitrate exposure during early pregnancy,” Semprini said, comparing the impact of nitrate to about 15% of the harm caused by smoking—a risk he believes is underaddressed.

Some cities have launched programs to reduce nitrate in water, but these efforts are costly and require thorough cost-benefit analyses. As concerns grow, this research underscores the need for updated policies to safeguard public health.

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