Guest Blog: Nitrates and Birth Outcomes

This guest blog comes from Jason Semprini, an Assistant Professor of Public Health at Des Moines University. His research uses novel data linkages and causal inference methods to evaluate the impact of public health policies or environmental exposures on health outcomes and equity.

Iowa is currently facing an unprecedented drinking water crisis. Recent reports indicate alarming nitrate levels in the Raccoon River; so high that city officials enacted emergency measures such as lawn water bans, to ensure water treatment facilities could comply with regulatory standards for safe drinking water. Unfortunately, at least for pregnant women, any level of nitrate in drinking water appears unsafe.

In my peer-reviewed study published by PLOS Water, I analyzed nearly 360,000 Iowa birth records from 1970 to 1988, linking births to nitrate measurements in public drinking water at the time of conception. During this time frame, nitrate levels in public water increased 8% annually. Although the data is old, the results still concern us all today.  

Consistent with evidence outside of Iowa, I found that prenatal nitrate exposure at levels far below the current EPA standard of 10 mg/L significantly increases risks of adverse birth outcomes such preterm birth and low birth weight. Specifically, early prenatal exposure to nitrate levels as low as 0.1 mg/L increased the likelihood of preterm births. Exposure at levels of 5 mg/L, just half the EPA threshold, was linked with an elevated risk of low birth weight. These findings demonstrate that any amount of nitrate exposure during pregnancy may harm infant health.

The Impact of CAFOs on Water Quality

Farms with livestock operations have dotted Iowa’s landscape for more than a century, but the number of livestock reared in Iowa has exploded in the last 30 years. Most of the growth has been in the form of large, concentrated animal feeding operations (CAFOs), especially large hog and hen confinements.

Ninety-five percent of Iowa's counties produce more animal manure than human waste, which can threaten local water sources with nitrates. Accumulated nitrates, found in livestock waste, contribute to a variety of health problems including thyroid disease, cancer, birth defects, and pregnancy complications. Learn more about nitrates at our newest blog, IEC Explainer: Nitrates and Public Health.

Advancements to Regulate CAFOs in Minnesota

Minnesota is emerging as a leader in enacting regulations for CAFOs. The Minnesota Pollution Control Agency (MPCA) is working to address nitrate contamination by updating existing animal feedlot rules. The new rules will address excess fertilizer application and nutrient runoff which contribute to fish kill events and polluted drinking water for public supplies and private well owners.

After a series of public meetings, officials from MPCA and other regulators will create a task force to address manure pollution. This will include farmers, environmentalists, and other residents as they draft new rules. Read more from the Minnesota Star Tribune.

Get Involved

• June 30: Protecting Iowa Wetlands - Virtual
• July 8: Cancer in Iowa Listening Session - Albia
• July 15: Drought, Deluge, and Drinking Water - Virtual
• July 16: Cancer in Iowa Listening Session - Elkader
• July 17: Cancer in Iowa Listening Session - Decorah
• July 23: Cancer in Iowa Listening Session - Red Oak
• July 30: Toxic by Design: Understanding Coal Ash Pollution in Iowa - Virtual

Cancer in Iowa Listening Sessions
Iowa has the second-highest cancer rates in the nation, and it is among only two states where cancer rates are increasing. We want to hear from you: Iowans who wish to learn more about cancer in our state, and Iowans who have been impacted by cancer. Register for a listening session near you.

Protecting Wetlands Webinar
On Monday, IEC's General Counsel Michael Schmidt and Hardin County farmer John Gilbert will present on the impact of wetlands and the Swampbuster case. This free webinar will include background on IEC's intervention into the federal case, the many benefits of wetlands, what the decision means for farmers.

Hear from IEC's Water Program Director

Hello, Weekly Water Watch readers!

As you can imagine, our staff have received many questions from concerned Iowans about the safety and reliance of their drinking water this week. While IEC is closely monitoring source water nitrate levels, we encourage you to reach out to your water utility with questions and read the FAQ responses from Central Iowa Water Works. You can also check out this video on our social media where I break down what nitrates are, their impact to drinking water, and common misperceptions.

Have a wonderful weekend!
- Colleen Fowle