Dental News - Tap water good for teeth but may cause higher blood lead levels

Dental Tribune International

Thu. 11. January 2018

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CHAPEL HILL, N.C., U.S.: American children and adolescents who drink tap water, which is typically fluoridated, are much less likely to have tooth decay, according to a new study. However, researchers have confirmed that those who consume tap water are more likely to have elevated levels of lead in their blood compared to those who primarily drink bottled water.

Drs. Anne Sanders and Gary Slade, of the Department of Dental Ecology at the University of North Carolina in Chapel Hill, analyzed a nationally representative sample of nearly 16,000 children and adolescents, aged from two to nineteen years old, who participated in the National Health and Nutrition Examination Survey (NHANES), from 2005 to 2014. More than 12,000 records included data on blood lead levels and about 5,600 contained dental caries examination data. NHANES is the U.S. benchmark for the national surveillance of blood lead levels and is the sole national source of dental examination data.

Following an at-home interview, participants visited a mobile examination center where they donated a blood sample, completed a dietary interview and underwent a dental examination. An “elevated blood lead level” was defined as having at least three micrograms of lead per deciliter of blood. “Tooth decay” was defined as the presence of one or more tooth surfaces that are affected by dental caries, as determined by dental examiners using a standardized protocol.

According to the results of the study, children and adolescents who did not drink tap water (about 15 percent) were more likely than tap water drinkers to have tooth decay, but were less likely to have elevated blood lead levels. Those who drank tap water had a significantly higher prevalence of elevated blood lead levels than children who did not drink tap water.

Overall, nearly 3 percent of children and adolescents had elevated blood lead levels and almost 50 percent had tooth decay. Among American children and adolescents, one in five living below the federal poverty level, one in four African Americans and one in three Mexican Americans do not drink tap water—vastly exceeding the one in twelve non-Hispanic, white children who do not.

“Elevated blood lead levels affect only a small minority of children, but the health consequences are profound and permanent,” explained Sanders. “On the other hand, tooth decay affects one in every two children, and its consequences, such as toothache, are immediate and costly to treat.”

The study’s statistical analysis also took into account other factors that could account for the relationship between the non-consumption of tap water and blood lead levels and tooth decay. A limitation of the study was that the fluoridation status of the participants’ tap water was unknown, therefore the observation that drinking tap water protects against tooth decay may be an underestimate of fluoride’s protective effect.

“Our study draws attention to a critical trade-off for parents: children who drink tap water are more likely to have elevated blood lead levels, yet children who avoid tap water are more likely to have tooth decay,” commented Slade. “Community water fluoridation benefits all people, irrespective of their income or ability to obtain routine dental care. Yet, we jeopardize this public good when people have any reason to believe their drinking water is unsafe.”

Public awareness of the hazards of lead-contaminated water has increased since 2014, when concerns were raised after the drinking water source for Flint in Michigan was changed to the untreated Flint River. A federal state of emergency was declared and Flint residents were instructed to use only bottled or filtered water for drinking, cooking, cleaning and bathing.

The study, titled “Blood lead levels and dental caries in U.S. children who do not drink tap water,” was published ahead of print online in November 2017. It will appear in the American Journal of Preventive Medicine in February, 2018.