Freshly adjusted federal guidelines for fluoride levels in water hold special significance here.

In 1945 Grand Rapids became the first city in the country to add fluoride to its municipal water system, a public health triumph quickly duplicated elsewhere. Today, more than two-thirds of public water systems use fluoridation to promote healthy teeth.

The federal announcement recognizes that excessive amounts of fluoride can be harmful, causing spots on teeth and fracture-prone bones. The findings, however, do not recommend complete removal of the chemical from water systems, as some activists advocate. Fluoride in water remains a safe, cost-effective and easy way to promote dental health, which is tied closely to over-all health. The new government guidelines suggest fluoride should be adjusted, not discarded.

The U.S. Department of Health and Human Services last week recommended a reduction in the fluoride level to 0.7 parts per million. The standard since 1962 has been a range of 0.7 to 1.2 parts per million. Local municipal water systems maintain fluoride levels greater than the new recommended optimum level. The Grand Rapids water system, which serves the city and areas beyond, uses 1 parts per million. Wyoming’s system, which also serves communities beyond its own borders, uses 1.4 parts per million. Those systems should review standards now and change them as needed.

However, the new recommendation should not feed the flawed notion — promoted on and off since the advent of fluoridation — that fluoride must be removed entirely from drinking water. The World Health Organization, the American Dental Association (ADA), the American Medical Association, the Centers for Disease Control and Prevention — all affirm the proven benefits of fluoride in drinking water in the proper amounts. The American Dental Association has estimated that fluoride reduces tooth decay by as much as 40 percent.

The effects of over-fluoridation range from enamel fluorosis, a discoloration and pitting of tooth enamel, to skeletal fluorosis, which increases bone fractures. A recent government study found that about 2 out of 5 adolescents have tooth streaking or spottiness because of too much fluoride. These new levels are meant to address that problem.

At the end of the last century the CDC named fluoridation one of the 10 great public health achievements of the previous 100 years. Grand Rapids led the way. There is every good reason to continue to review and modify the science behind that significant advance. There’s no cause to turn back.

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