USA - CDC Asks for Comments on New Fluoride Level Proposal

For more than 70 years, fluoride has been added to community water systems to prevent tooth decay and improve oral health. According to the Centers for Disease Control and Prevention (CDC), fluoride works best at levels of 0.7 mg/liter. Now the agency is seeking comments on its proposed recommended range of 0.6 to 1.0 mg/liter, which would still maximize prevention of tooth decay while minimizing the possibility of dental fluorosis.

“Water operators work to keep the fluoride levels at 0.7 mg/liter. There are factors that influence the amount of fluoride additive that they have to add to keep it at that level,” said Johnny Johnson Jr, DDS, MS, president of the American Fluoridation Society. “What this rule is doing is to establish the lowest level the operator can get to and still be considered to be preventing decay as desired. It also establishes an upper operating level which is intended for them not to go above.”

In 1962, the federal government recommended a range of 0.7 to 1.2 mg/liter for community water systems. The range was established due to differences in climate across the country, as residents of warmer regions drank more water than those in more temperate areas. By 2015, noting that air conditioning had negated many of these differences, the Public Health Service (PHS) released a single new recommended level of 0.7 mg/liter. 

But community water systems have to account for varying levels of naturally occurring fluoride and adjust their additions accordingly. Also, surface sources of water will have changing levels of fluoride based on recent rainfall and evaporation, compared to underground sources. When water levels are lower in reservoirs, fluoride becomes more concentrated. When the season has been rainy and water levels are higher, fluoride becomes more diluted. 

“Think of it as you trying to maintain 55 mph on the highway. Sometimes as you start to go up a hill, you’ll decrease in speed and have to press on the accelerator to get up to 55. Then as you crest the hill, you’ll pick up a little speed and have to ease off the accelerator. This is exactly what the CDC is establishing for the water operators, a range around 0.7 mg/liter that is considered an acceptable operating range.” 

According to the CDC, several state water fluoridation and drinking water programs asked for revised operational control range guidance around the 0.7 mg/liter level after the 2015 PHS recommendation. These programs asked the CDC to consider how they could stay within an operational range on a daily basis. Since these systems favor lower feed rates for adding fluoride to water, the CDC recommended an asymmetrical range of 0.6 to 1.0 mg/liter to consistently meet the 0.7-mg/liter target.

Published studies have shown that water systems can maintain at least 80% of daily measurements during the month within the proposed operational control range, the CDC reports. The CDC also recommends that monthly average fluoride levels be maintained within the proposed operational control range, with 80% of daily measurements of fluoride maintained within the proposed operational control range. The CDC’s request for comment does not apply to water systems with natural fluoride levels exceeding the proposed range. 

Written comments may be submitted via the Federal eRulemaking Portal or by mail to the Division of Oral Health, Centers for Disease Control and Prevention, 4770 Buford Highway, MS S107-8, Atlanta, Ga 30341, attn: Docket Number CDC-2018-0064. All submissions must include the agency name and docket number and be received on or before October 11, 2018.

“Water operators have been asking for this since 2015,” said Johnson. “Government works slow at times. But the CDC was doing their due diligence on this wiggle room and now has to go through the comment period. Once that is done, the range will be published.”