Research conducted by a team of scientists from Aarhus University in collaboration with colleagues from the Geological Survey of Denmark and Greenland (GEUS) shows that the risk of colon and rectal Cancer increases with exposure to nitrates in Drinking water.
Nitrate contamination of groundwater resources and drinking water, originating primarily from fertilizers used in crop production, has long been suspected of posing an increased risk of cancer. Now, the largest public health study ever conducted on this issues reveals that there is a link, even when nitrate levels in drinking water are far lower than current safety levels set for drinking water.
For the study, which was recently published in the International Journal of Cancer, the researchers looked at the levels of nitrate that Danish consumers were exposed to in their drinking water and compared this data to cancer diagnoses in the country. The study, which is the largest of its kind in this research area, analyzed nitrate concentrations in drinking water samples collected from over 200,000 locations, and followed the health of 2.7 million Danish consumers between 1978-2011.
"Each year, approximately 5,000 Danes contract colorectal cancer, which can have many causes. Our study shows that nitrate in drinking water may be one of them," says Jörg Schullehner, PhD from the Department of Public Health at Aarhus University and lead author of the study. "In the study, people who were exposed to the highest concentration of nitrate in drinking water (above 9.3 mg per liter of water) had a 15 per cent greater risk of getting colorectal cancer compared to those who had least exposure (less than 1.3 mg per liter of water). The current drinking water standard is 50 mg nitrate per liter of water, but the increased risk of cancer could already be seen at concentrations greater than approximately 4 mg nitrate per liter of water."
The drinking water standard for nitrates in Denmark and other countries in the European Union comply with levels recommended by the World Health Organization (WHO) to prevent 'Blue Baby Syndrome' — which results from nitrite poisoning that prevents oxygen uptake by the body in infants and can be fatal.
The results of this research confirm suspicions that exposure to nitrate in drinking water increases the risk of colorectal cancer — the third most common form of cancer worldwide, and also very common in Denmark. Once nitrate is absorbed by the body it is converted into carcinogenic N-nitroso compounds, which pose the cancer threat.
According to Torben Sigsgaard, a professor in the Department of Public Health at Aarhus University and co-author of the study, the results of this study echo those of other international studies that suggest the standard for nitrate in drinking water should be lowered to protect consumers against other chronic health risks rather than just Blue Baby Syndrome alone.
According to Schullehner, data collected by GEUS surveys suggest that nitrate levels at public water utilities serving the majority of Danish consumers have been reduced over the last few decades and are currently low. The problem areas consist mostly of small private drinking water wells and areas where there is a high rate of nitrate leaching, particularly areas where the geological and soil conditions are conducive to nitrate leaching into the groundwater. These are the areas that we need to focus on, says Schullehner.
While the berkey water filter does remove nitrites, unfortunately nitrates are very difficult to remove from the water, and they are one of the only contaminants that the Berkey is unable to remove. We're hoping we can change this in the future.
Jörg Schullehner, Birgitte Hansen, Malene Thygesen, Carsten B. Pedersen, Torben Sigsgaard. Nitrate in drinking water and colorectal cancer risk: A nationwide population-based cohort study. International Journal of Cancer, 2018; DOI: 10.1002/ijc.31306