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Study Finds Fluoride in Utero Linked to Lower IQ After Birth

If you live in the United States, there is a good chance that the water you get from your tap is fluoridated. And that is for a good reason. Since it was introduced to the public water supply (for about 75 percent of Americans) more than 70 years ago, there has been a 25 percent reduction in cavities in both adults and children. But some people are concerned about the safety of fluoride, especially in high doses. A new study has indicated that there could potentially be something to worry about.

The study, which was published in Environmental Health Perspectives, looked at approximately 300 sets of mothers and their children in Mexico, following the cognitive development of the children over the course of twelve years. In Mexico fluoride is not added to the water — people are instead exposed to it through other means, like supplements and fluoridated salt. Levels of fluoride in the mothers and children were evaluated by testing their urine.

CNN explains what the study found:

The study found a drop in scores on intelligence tests for every 0.5 milligram-per-liter increase in fluoride exposure beyond 0.8 milligrams per liter found in urine. However, although the researchers found a potential connection to a child's exposure to fluoride in utero, they found no significant influence from fluoride exposure on brain development once a child was born.

"Childhood exposure to fluoride is safer than prenatal. There is pretty good science now to support the fact that the fetal system tends to be more sensitive to environmental toxicants than once the child is born," said the study's lead author, Howard Hu, founding dean of the Dalla Lana School of Public Health at the University of Toronto.

The researchers stressed the fact that more studies need to be done on the issue. Since the levels of fluoride in American women were not measured, it is difficult to expand the findings to include other populations. And while low levels of fluoride are considered safe, high levels have been found to be toxic.

Previous studies have found fluoride to be a potential neurotoxin at extremely high levels. Many of these studies have been conducted in China, where fluoride levels in water can be as high as 30 milligrams per liter.

The US Public Health Service recommends an optimal level of fluoride concentration of 0.7 milligrams per liter. The Environmental Protection Agency has set a limit of 4 milligrams per liter.

Chronic excessive intake of fluoride can lead to discoloration of teeth and skeletal fluorosis, a condition that results in extreme joint and skeletal pain.

If your public water contains fluoride, there should be little cause for concern. But if you are pregnant, consider talking to your doctor if you also consume fluoride through supplements. Although the study was limited in its scope, it did show a correlation between high levels of fluoride during pregnancy and later cognitive development issues.