Children who drink tap water are at higher risk of lead exposure, which can be debilitating. Meanwhile, avoiding tap water, which contains helpful minerals, greatly increases your child’s risk of dental caries, which are less serious. These are the findings of a new study in the American Journal of Preventive Medicine. The results broadly suggest that, when it comes to choosing between tap water and bottled water for your children, you’re likely damned if you do and damned if you don’t.
“Elevated blood lead levels affect only a small minority of children, but the health consequences are profound and permanent,” said study co-author Anne E. Sanders of the University of North Carolina at Chapel Hill, in a 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.”
Parents don’t always trust tap water, perhaps with good reason. The 2016 lead crisis in Flint, Michigan is hard to forget — more than 100,000 residents were potentially exposed to high levels of lead, due to insufficient municipal water treatment. Flint isn’t alone. Even if every municipal drinking water source is now lead-free (an unlikely scenario), millions of Americans still get their drinking water from unregulated wells which can contain unsafe levels of lead and arsenic.
Still, there are advantages to avoiding bottled water and drinking straight from the tap. One obvious factor is cost — it is important for children to remain hydrated, and tap water is free. But there’s another advantage. Data from the Centers for Disease Control and Prevention suggests that, since fluoride was added to many cities’ water supplies, tooth decay has plummeted.
To better understand tap water’s double-edged sword, Sanders and colleagues surveyed 16,000 children between the ages of two and 19, interviewing many of them at home, collecting blood samples, and performing dental exams. They found that roughly 15 percent of children never drink tap water, and that these children were far more likely than others to have tooth decay — and slightly less likely to have elevated blood lead levels. On the other hand, those who drank tap water regularly were more likely to have high levels of lead in their blood, but less likely to have cavities. The data also revealed a racial divide — between 1 in 3 and 1 in 4 minority children reported never drinking tap water (perhaps due to Mexican immigrants, who still remember Mexico’s public water crises). Conversely, only 1 in 12 white children avoid tap water.
Although the study’s sample size was large and the results conform to what other researchers have long suspected about both lead exposure and dental caries, there are a few limitations. Lead exposure can come from many places — old paint chips, gasoline, solder — and the researchers did not confirm that the children with elevated blood lead were exposed to tap water with unsafe lead levels. Similarly, many factors can influence tooth decay, and the researchers did not confirm that the children with tooth decay were drinking tap water that was fluoridated.
Nonetheless, the study suggests that parents have a tricky decision to make when it comes to choosing drinking water for their kids. The researchers suggest that tap water is still probably the best choice — the risk of lead exposure is low, and the dental health benefits of fluoridation have been demonstrated again and again. “Community water fluoridation benefits all people, irrespective of their income or ability to obtain routine dental care,” said co-author Gary D. Slade, also of the University of North Carolina, Chapel Hill, in the statement. “We jeopardize this public good when people have any reason to believe their drinking water is unsafe.”