All but two of the studies were conducted in China, where water fluoride levels were sometimes much higher than is typical in the U.S.
LeFevre added in an email, “The Task Force recommendation for supplements when the water supply is deficient in fluoride is based on the benefits and harms found in trials of supplementation in those selected circumstances. The Task Force did not examine the epidemiologic studies related to fluoridation of water.”
“Dental varnish is not expected to have much systemic absorption,” he wrote.
Grandjean, who was not involved in the new recommendations, said he could not assess possible risks of water fluoridation in the U.S. and called for research to clarify fluoride’s role in potential adverse effects on brain development.
In 2011, the U.S. Department of Health and Human Services lowered recommended fluoride limits in water, saying too large a dose of the mineral, which is also found in toothpaste and mouth rinses, may have damaged some children’s teeth.
The new task force report, published in Pediatrics, points out that about 42 percent of children between two and 11 years old get cavities in their baby teeth. That percentage decreased from the early 1970s until the mid-1990s, when tooth decay began increasing again, particularly in preschool-aged children.
Hayes said she regularly sees children with mouths full of unhealthy teeth in her Chicago pediatric dental practice. Just this week she said she treated a four-year-old girl with two front teeth that needed to be extracted, six molars that needed crowns, two molars that needed fillings and four that needed partial root canals.
The child had been drinking four cups of soda per day, Hayes said. Now, at Hayes’ insistence, she drinks just milk and water.
Renee Sharp, research director for the Environmental Working Group, a research and advocacy group, said she was more comfortable with the new recommendation on professionally applied fluoride varnish than she was with the recommendation on parent-administered fluoride drops for infants.
She is based in Oakland, California, and was not involved with the guidelines.
“We certainly have concerns with the drops because it’s so imprecise, and it would be so easy to overexpose a child to fluoride,” Sharp said.
The task force recommendations do not address educating parents about optimal dietary and other health practices for their children’s oral hygiene. The guidelines do call for more research on the question.
The panel members also conclude there is not enough evidence to recommend that primary care doctors routinely