Nitrates and Nitrites in Drinking Water

Nitrates and nitrites are naturally occurring chemicals in our environment, found in soil, water, and plants. While they are not typically harmful at low levels, high concentrations in drinking water can pose a significant health risk. It’s essential to monitor and control nitrate and nitrite levels, especially in water sources such as wells, rivers, and lakes, where contamination is more common.

Nitrates and nitrites come from various sources, both natural and human-made. They can enter the water supply through agricultural runoff, industrial pollution, or even improper disposal of waste. Ensuring safe drinking water involves understanding the potential risks posed by these chemicals and taking the necessary steps to remove or reduce them from our water sources.

In this article, we’ll explore what nitrates and nitrites are, how they enter the water supply, their health effects, and how we can monitor and manage their presence in our water.

Nitrates (NO₃⁻) and nitrites (NO₂⁻) are compounds that contain nitrogen and oxygen. These chemicals are part of the nitrogen cycle, which is a natural process that occurs in soil and water, helping plants grow. However, the levels of nitrates and nitrites can increase due to human activities, leading to contamination of drinking water.

Nitrates

Nitrates are a naturally occurring form of nitrogen found in soil, water, and air. They are essential nutrients for plants, as they help in their growth. When plants absorb nitrates from the soil, they can use them to build proteins and other essential compounds. However, when nitrates accumulate in high levels in drinking water, they can be harmful.

Nitrites

Nitrites are similar to nitrates but differ in their chemical structure. Nitrites are often produced in the water when nitrates are reduced by bacteria. While nitrites are less stable and more reactive than nitrates, they are also harmful when present in high concentrations.

Short-Term Health Effects

• Methemoglobinemia (Blue Baby Syndrome): The most well-known health effect of high nitrate levels is methemoglobinemia, also called “blue baby syndrome.” Infants under six months old who drink water with high levels of nitrates are at risk of this condition. Nitrates can interfere with the ability of hemoglobin in the blood to carry oxygen, leading to suffocation-like symptoms. Symptoms include a bluish tint to the skin, especially around the mouth and hands. 
• Stomach irritation: High nitrate levels can irritate the stomach lining, leading to nausea, vomiting, and diarrhea.

Long-Term Health Effects

• Cancer risks: Some studies suggest that long-term exposure to high levels of nitrates and nitrites may increase the risk of certain types of cancer, such as colon, stomach, and bladder cancer. This is believed to occur due to the formation of nitrosamines, which are carcinogenic compounds formed when nitrites interact with amines in food or the body. 
• Thyroid problems: Excessive nitrate intake can potentially disrupt thyroid function, particularly in individuals who are already at risk for thyroid disease.

Vulnerable Populations

• Infants: Infants are especially vulnerable to the effects of nitrates due to their developing digestive and respiratory systems. They are more likely to develop methemoglobinemia from consuming nitrate-contaminated water. 
• Pregnant women: Pregnant women may be at a higher risk of certain health issues if exposed to high levels of nitrates, particularly related to their thyroid function or the development of their baby.
• Elderly individuals and those with weakened immune systems: Older adults and individuals with compromised immune systems may also be at higher risk from the effects of nitrate contamination, including increased susceptibility to infections or other illnesses.

Signs of Contamination:

• Taste and smell: Nitrate-contaminated water often has no distinct smell or taste, making it difficult to detect without testing.

• Cloudy or discolored water: High levels of nitrates and nitrites can cause a cloudy appearance in the water.

Laboratory Testing –

The most accurate way to detect nitrates and nitrites is through a laboratory test. Water testing kits specifically designed for nitrates and nitrites can be purchased at hardware stores or online. These kits are easy to use and provide results within minutes, though laboratory testing is still more reliable.

Safe Limits –

• EPA Standards: The U.S. Environmental Protection Agency (EPA) sets a maximum contaminant level (MCL) for nitrates at 10 milligrams per liter (mg/L), and 1 mg/L for nitrites in drinking water.

• WHO Guidelines: The World Health Organization (WHO) has similar guidelines for safe nitrate levels in drinking water, emphasizing the need to control levels to protect vulnerable populations.

Effective Water Treatment Methods –

• Reverse Osmosis (RO): Reverse osmosis is one of the most effective ways to remove nitrates and nitrites. RO systems filter out impurities, leaving behind clean water. They are often used in homes with well water.

• Distillation: Water distillers can also reduce nitrate and nitrite levels. These systems boil the water, capture the steam, and condense it back into liquid, leaving contaminants behind.

• Ion Exchange: Ion exchange systems are designed to replace nitrate ions with other harmless ions like chloride, reducing nitrate levels in water.

• Activated Carbon Filters: While activated carbon filters are excellent for removing chlorine, VOCs, and other contaminants, they are less effective at removing nitrates and nitrites. It is best to use these in combination with other systems.

Prevention Tips –

• Maintain septic systems and wastewater treatment: Ensure proper maintenance of septic tanks and wastewater systems to prevent the release of nitrates into groundwater.

• Use less fertilizer: Reduce the use of chemical fertilizers in agriculture and landscaping, as they are a primary source of nitrate contamination.
  
• Proper disposal of waste: Be mindful of waste disposal practices to prevent the introduction of nitrates and nitrites into local water supplies.