Mandatory water fluoridation introduced by the former Queensland government is being rolled back by some local councils, which have been given the power to decide whether to continue with the public health measure. There are even indications that some local government councils have moved with remarkable haste to decide to cease water fluoridation at the behest of a vocal, small minority of anti-fluoridationists.

Unfortunately for their citizens, councils may have made their decision without dedicating enough time and resources to become properly informed. And it’s not a decision of no consequence.

The burden of pain and discomfort, disfigurement and disability from dental decay is surprisingly large in Australia because dental decay is so ubiquitous. The ideal solution to such a widespread problem needs to help all of the population. Measures that reach very large numbers of people but require little or no individual effort are best, and they need to save more dollars in averted treatment than what they cost to implement.

Water fluoridation for the prevention of dental caries is an excellent example of such a public health measure. It’s been described as one of the ten great public health measures of the 20th century and is one of only a handful of health promotion measures in Australia that’s cost saving.

The decision to fluoridate is usually made by elected members of government and it’s implemented at the community level. People making the decision need to consider the public good of the measure, balancing the evidence of potential benefit and possible harms.

Queensland’s former Labor government introduced the Water Fluoridation Act 2008, mandating the fluoridation of water supplies across the state. But last year, the current Liberal-National government changed the law so local governments now decide whether to fluoridate water supplies.

The Act was based on research from the 1990s that showed children who were continuous residents of Brisbane had considerably more dental decay than their counterparts in Townsville, which has had fluoridated water since 1964. Not only did a higher percentage of Brisbane children have dental decay, their decay was also more severe.

Research looking at data from across the 1990s in Queensland and South Australia showed that children without access to water fluoridation developed new decay at a higher rate over a three-year period than those who did have access. More recently, research examining the interplay between sweetened beverage consumption and exposure to fluoridated water showed children without the latter had less protection against the former, causing increased tooth decay.

Fluoridation had covered 87% of Queensland before the Water Fluoridation ACT 2008 was changed and it was predicted that the dental decay rates in previously non-fluoridated areas would decrease to levels comparable to those seen in fluoridated Townsville. The drop in decay rate being denied some children in Queensland can be surmised from similar situations elsewhere.

A 2009 report compared the tooth decay rate in the Blue Mountains in New South Wales, which fluoridated from 1992, to the Hawkesbury area, which had been fluoridated in 1968. It found that the dental decay rate among five to eight-year-old children in Hawkesbury didn’t reduced much from 1993 to 2003 (2.99 to 2.79 teeth per child), but across the same period in the Blue Mountains, the rate fell from 4.22 to 2.48 per child.

Among eight to eleven-year-olds, the adult teeth decay rate in Hawkesbury children reduced from 1.96 to 1.92 teeth per child, but for the Blue Mountains children, the rate fell from 2.21 to 1.73 teeth.

While the changes to the Water Fluoridation Act 2008 moves the decision closer to the individual community, it doesn’t change the requirement for the decision to be informed and considered. Councils have a duty of care to ratepayers and their children and should seek out and consider the guidance of national health authorities such as the National Health and Medical Research Council, and Food Standards Australia and New Zealand.

Guidance about the claims made in the lay media about the benefits and risks of water fluoridation is also available from state health authorities. Unfortunately, the changes to the Water Fluoridation Act 2008 abolished the Queensland Fluoridation Committee, which might have served as a resource for councils making a decision.

Councils have no obligation to publicly indicate that they will consider water fluoridation or when that might occur. And local governments don’t bear the cost of decommissioning fluoridation plants and can eliminate an ongoing operational cost of water fluoridation. But ratepayers and the state government (and possibly the federal government in the future) will carry the cost of preventable dental decay.