Nitrates in Water and Health Risks

Nitrates can be a naturally occurring compound that is found in everything from leafy greens to manure.

But, high concentrations of nitrates in your drinking water (typically due to the use of synthetic fertilizers) may pose a health risk to you and your family.

The relationship between nitrates and health is a complex topic, and there is a growing body of research to digest.

This makes it an important issue to discuss with your doctor if you live in an area with high nitrates in the water supply, and you are concerned it may be impacting your health.  

In this post, we’ll explore the research around nitrates and health—and share clear guidance on how to address this concern.

What regulations currently exist for nitrates in drinking water? 

The EPA (Environmental Protection Agency) has set the maximum contaminant level for nitrates in public drinking water supplies in the United States as 10 mg/L (as nitrate-nitrogen [NO3-N]).

The EPA summarizes the rationale for this level as follows:

Infants below the age of six months who drink water containing nitrate in excess of the MCL (maximum contaminant level) could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue baby syndrome.

What level of nitrates in drinking water is safe for chronic exposure? 

The federal maximum contaminant level of 10 mg/L for nitrates in drinking water was set in 1962, specifically in relation to acute illness in infants. All public drinking water systems must meet this minimum standard.

Unfortunately, we do not have large-scale definitive studies about the safe limit for chronic exposure to nitrates in water for adults or children. However, the EPA does state on its website that “while nitrate does occur naturally in groundwater, concentrations greater than 3 mg/L generally indicate contamination.”

Even though we do not have definitive answers, there has been a growing number of early-stage studies associating nitrates in drinking water with multiple of health conditions, including:

• Pediatric Cancers (Brain Cancer, Non-Hodgkin Lymphoma)

• Adult Cancers (Colorectal, Gastric, Thyroid, Kidney, Bladder)

• Blue Baby Syndrome

• Headaches

• Nausea 

• Fatigue

• Abdominal Cramps

• Hypothyroidism

• Preterm Birth and Neural Tube Defects

Here’s a visualization of some of some of the study findings, as well as the guidance from the EPA:

Read the studies on colorectal cancer, pediatric brain and other CNS cancers, leukemia and lymphoma, and increased risk of ovarian cancer.

According to the a recent comprehensive study:

“The included studies provided some support to the hypothesis that nitrate in maternal drinking water may have some adverse health effects in the offspring, including preterm delivery, lower birth weight, and birth defects, also at drinking water levels below the current European and US drinking water standards.”

• Prenatal Exposure to Nitrate in Drinking Water and Adverse Health Outcomes in the Offspring (2023)

What areas of the United States have high nitrates in their water?

The first step to reduce your own level of exposure and risk is to understand whether you reside in an area with high nitrates. (These areas tend to correspond with agricultural activity.)

Below is a map from the U.S. Geological Society of areas in the United States where nitrate contamination levels of groundwater are high. If you live in one of these regions, you can likely conduct a search of your own state to find a county-by-county map.

Talking to your doctor about nitrates and your health

While we wait for more broad guidance on safe levels for chronic exposure to nitrates, you can take individual action and talk to your doctor about your health risk.

The American Academy of Pediatrics, shares this about the role of providers in providing education on drinking water from private wells:

“Pediatric care providers can be effective communicators when they partner with local and state public health authorities in counseling families about routine and periodic well water testing.^133,134  The states, the Navajo Nation, and the EPA offer suggested inspection and testing schedules on their websites. Testing can be expensive, and the AAP encourages states and counties to provide free or low-cost testing to families who need their water tested and cannot afford it. Pediatric care providers can also counsel families about other household practices to ensure safe drinking water…” 

I personally recommend advocating for an occupational therapy referral, if you would like a health care professional to dig deeper into this with you. That way, you can connect with a health professional who will take the time to sit down with you and provide education on what we know (and don’t know) about nitrates—and how the research may be related to your own health condition. OTs can also provide assistance with testing the water in your home to ensure it is safe—and helping you navigate potential programs for mitigation.

Removing nitrates from your water: a complex problem with a straight forward solution 

When you start reading about water, you quickly learn that high nitrates may be the canary in the coal mine for multiple other contaminants. (And, as this review indicates, the devil may be in the details of these interactions.)

Luckily, the most straightforward course of action is to install a reverse osmosis (RO) system, which will ideally decrease levels of nitrates AND other contaminants.

Remember, to prevent acute illness, shoot for a reading that is below 10 mg/L.

There is not a definitive target level to reduce your risk of health impacts from chronic nitrate exposure in your drinking water, but most signs point to “lower is better.” (I personally try to keep my levels below 3 mg/L.) 

My hometown of Aurora, Nebraska, has become a case study on whether the maximum safe limit for chronic exposure should be lower for adults and children.

Thankfully, our state offers some testing and RO programs through their Natural Resources Districts and a state-wide tax credit for households with satisfactory readings. In Nebraska you can also contact your local health department to learn more about publicly available testing support.

The more our state agencies hear from concerned citizens, the more likely they are to expand and continue to fund programs like this.

How to learn more about this complex topic 

There is a lot of nuance to this conversation. Questions for further exploration include:

• How do nitrates interact with other farm chemicals?

• How do they interact with heavy metals found in the ground?

• Are nitrates really considered a “canary in the coal mine?” Why?

• What is needed for us to definitively say that nitrates cause cancer?

Learn more in this one-hour podcast with Dr. Jesse E. Bell!