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Study Estimates Thousands Of Cancer Cases Are Linked To Nitrates In Drinking Water

A peer-reviewed study published this week estimates thousands of cancer cases are linked to nitrate expsoure. Researchers say ag states like Iowa face greater risks.

A new analysis shows Iowans may face higher risks of certain health issues due to nitrate pollution in drinking water. Across the country, thousands of cases of certain cancers and birth defects may be linked to the contaminant, researchers found.

A peer-reviewed study published this week in the journal Environmental Research estimates between 2,300 and 12,594 cancer cases a year nationwide may be linked to nitrates in drinking water. The team, which includes researchers from the Environmental Working Group and Duke University, also estimated some 4,700 cases of babies born with very low birth weight, very pre-term birth or neural tube defects may be linked to nitrates as well.

The current legal limit set by the U.S. Environmental Protection Agency for nitrates in drinking water is 10 parts per million. But recent studies suggest the chance of colorectal and thyroid cancers and birth defects goes up at even lower levels of exposure.

“Epidemiological data suggest that nitrate impacts on human health may occur at nitrate concentrations present in drinking water in the United States today,” the researchers wrote. “Among health impacts observed in epidemiological studies of nitrate in drinking water, colorectal cancer shows the strongest association, based on long-term studies with large numbers of study participants.”

Alexis Temkin of the Environmental Working Group and her co-authors tallied the potential cases, based on detected levels of nitrates in drinking water systems across the country.

“We found that typically there could be sort of a large public health impact occurring at levels that are below the current legal standard,” Temkin said.

Temkin says agricultural states, including Iowa, are at a greater risk, due to the use of nitrate-rich fertilizer and manure.

“We tried to look at the rates and saw that states like California and Iowa had some of the higher rates, where we know that there is a lot of agricultural practices, and definitely many communities that can be affected by elevated nitrate levels,” Temkin said.

Advocates have pushed the EPA to review its regulatory standard for nitrates in drinking water, and consider lowering the legal limit, based on recent studies showing the risk of disease increasing at lower levels.

In April of 2019, the agency announced reviewing the standard for nitrates and other contaminants was not identified as a priority in fiscal year 2019, saying “the assessments have been suspended but may be restarted as Agency priorities change.”

Kate Payne was an Iowa City-based Reporter