Nitrate in drinking water can increase the risk of birth defects
The risk of a newborn baby being born with birth defects is greater if the mother has drunk drinking water with even small amounts of nitrate during pregnancy. This is shown by a large study carried out by researchers at the universities in Aarhus and Illinois, USA. The results have been published in the journal Lancet Regional Health Europe.
If the foetus is exposed to nitrate, which is found in our drinking water, the risk of the child being born with birth defects may increase. A new research result found particular evidence showing that exposure to nitrate can increase the risk of defects in the eye.
"Our findings confirm previous research which has documented foetal defects in relation to exposure to nitrate in drinking water. This leads to the obvious question; whether the current threshold values for nitrate in drinking water are adequate to protect our children," explains Professor Leslie Stayner from the University of Illinois, who is the principal author of the article.
The researchers studied a cohort of more than one million births in Denmark and calculated nitrate concentrations based on 130,944 samples of drinking water from almost 4000 public waterworks. The levels of nitrate were generally below the current threshold values in Europe and the USA. The threshold value for nitrates in drinking water in Denmark is determined on the basis of recommendations issued by the WHO.
Originates from fertiliser
The results also suggest that nitrate plays a role in defects in the ear, face, neck and nervous system among children born to mothers under the age of 25.
"We don't know why the mother's age plays a role in connection with foetal defects, but we think that it may be an effect of something other than nitrate pollution, such as smoking and air pollution, and we therefore view thus finding as a little uncertain," says Torben Sigsgaard from Aarhus University, who is behind the Danish contribution to the study.
Nitrate is one of the most frequently identified pollutants in water systems around the world, and originates primarily from agricultural fertiliser. For decades, not only has nitrate been subject to environmental focus, it has also been suspected of being a carcinogen.
"These results are particularly worrying for areas of the world with intensive agriculture and higher exposures to nitrate, and there’s no doubt that further studies are clearly warranted," says Leslie Stayner.
The results of the study remained largely unchanged when the analysis was limited to mothers who had not been exposed to concentrations of nitrate above the current threshold values.
Background for the results
- The study is a cohort of more than one million births in Denmark.
- Partners: The Center for Integrated Register-based Research, CIRRAU, Aarhus University; The University of Illinois, School of Public Health, Chicago; Groundwater and Quaternary Geology Mapping, The Geological Survey of Denmark and Greenland; The Department of Public Health, Aarhus University; The Department of Public Health, The University of Copenhagen.
- The study is financed by: Grants from the National Institute for Environmental Health Sciences and the Karen Elise Jensen Foundation.
- The scientific article can be read in Lancet Regional Health Europe.
Contact
Professor Torben Sigsgaard
Aarhus Universitet, Institut for Folkesundhed
Mail ts@ph.au.dk
Mobile: 28 99 24 26