Parents face critical trade-off in deciding between tap, bottled water

Mary Otto

About Mary Otto

Mary Otto, a Washington, D.C.-based freelancer, is AHCJ's topic leader on oral health and the author of "Teeth: The Story of Beauty, Inequality, and the Struggle for Oral Health in America." She can be reached at mary@healthjournalism.org.

Worries about the safety of the nation’s tap water were already a reality before the 2014 lead-contamination crisis in Flint, Mich.

Exposure to lead poses serious health risks to children. And while research shows blood lead levels have decreased substantially over the past 40 years in response to the federal Safe Drinking Water Act and Lead and Copper Rule, concerns about corrosion from aging lead service lines and lead pipes in older homes have fueled questions about water quality in communities nationwide.

Now a new study, based upon a decade’s worth of federal data, offers insights into tap water consumption patterns across ethnic and socioeconomic groups and their impact upon children’s health.

Researchers found that children who don’t drink tap water are less likely to have elevated levels of lead in their blood. But at the same time, children who are not drinking tap water are missing out on the cavity-fighting benefits of fluoride, which has been added to most public water supplies for decades. According to the study, published in the American Journal of Preventive Medicine, children who do not drink tap water suffer from higher levels of oral disease.

“Our study draws attention to a critical trade-off for parents: children who drink tap water are more likely to have elevated lead levels, yet children who avoid tap water are more likely to have tooth decay,” noted one of the paper’s authors, Gary Slade of the Department of Dental Ecology at the University of North Carolina at Chapel Hill, in a press statement released at the time of the paper’s publication.

Researchers analyzed data from the National Health and Nutrition Examination Survey (NHANES) to reach their conclusions. They looked at a nationally-representative sample of nearly 16,000 children and adolescents ranging in age from 2 to 19 who participated in NHANES from 2005 to 2014. Their records included data on blood lead levels, tooth decay rates and water consumption habits.

About 15 percent of the children reported they did not drink tap water.

Overall, the researchers found elevated lead levels in 3.1 percent of children who consumed tap water and 1.9 percent in those who did not.

(The threshhold for an elevated blood lead level was defined as 3 or more micrograms per liter.)

Conversely, caries rates were higher for those who did not drink tap water. Nearly half of children – 49 percent – who drank tap water had tooth decay but 55.3 percent of children who did not drink tap water had caries.

Water consumption patterns varied widely among ethnic groups, the researchers found. While only 8 percent of non-Hispanic white children reported that they did not drink tap water, 21.5 percent of non-Hispanic black children said they did not and more than 32 percent of Mexican-American children said they did not drink tap water.

“Aversion to tap water among Mexican-American children is noteworthy,” the authors wrote in the paper. “One explanation is the legacy of experiences in Mexico, where rapid industrial development and urbanization produced high levels of environmental pollution and unsafe drinking water.”

The prevalence of elevated lead levels was higher among boys than girls, among preschool children than older children, among African-American children than non-Hispanic whites, and among children from low income homes versus higher income homes.

The study had limitations, the authors acknowledged. Environmental sources of lead, in paint chips, dust, gasoline and solder might have confounded the relationship between tap water and blood lead levels in the children. The researchers also noted that the fluoridation status of the participants’ tap water was unknown. Still, they stressed, the study offers new insights into the connections between water quality and the health of children.

“Elevated blood lead levels affect only a small minority of children but the health consequences are profound and permanent,” observed study co-author Anne E. Sanders, also from UNC, in the statement.

“On the other hand, tooth decay affects one in every two children and its consequences, such as toothache, are immediate and costly to treat.”

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