Yesterday Canadian economics blogger Mike Moffatt posted his thoughts about the costs of reducing the murder rate by 30 percent through water treatment. The post was based on a Big Think article that studied correlations between higher lithium amounts in public drinking water and drops in suicides and violent crime rates.

Lithium, a mood-booster, is used as psychotropic treatment against bipolar disorder. The theory, in a nutshell, is that giving the public a little bit of lithium makes us all a little more mentally stable.

The idea’s met some outcry. Aside from the ethical issues surrounding mental health, the Big Think author notes that lithium is known to be more powerful than fluoride, with greater chances of side effects.

But lithium isn’t the only substance that can be added to public drinking water. Thiamine has been proposed as a means of eradicating Wernicke-Korsakoff syndrome among alcoholics. And the use of fluoride has repeatedly caused a stir.

After six decades of fluoride use in public water supplies, there is still little scientific consensus on the issue.

The U.S. Centers for Disease Control and Prevention listed fluoridation of drinking water among 10 great public health achievements of the last century. At a a price near one dollar per citizen each year, the U.S. surgeon general has lauded fluoridation for its cost-effectiveness. More than 65 percent of the population uses fluoridated water.

But WHO data shows little-to-no difference in oral hygiene between countries who chose whether to fluoridate public water. WHO only advocates fluoridation for countries with poor health infrastructure, and removal of fluoride from water sources with too much of the substance.

Most European countries, western and eastern, started fluoridating until the ’70s and ’90s, respectively. Some countries now fluoridate salt or even milk instead, and toothpaste with fluoride has been prevalent since the 1970’s.

This month, the U.S. government proposed lowering the amount of fluoride added to public water for the first time in almost 50 years over increasing rates of fluorosis among children.

Fluoridation gained prevalence in the Western world in the 1950s, decades after researches studied a lower rate of cavities in areas where water sources are naturally rich in fluoride. Under the red threat, paranoid Americans rallied against fluoridation, calling it a communist plot to undermine public health and brainwash the population. Some today even argue that fluoridation violates Nuremberg laws forbidding human experimentation.

Fluoridation has often been controversial in Canada. Anti-fluoridation activists often point to research claiming a correlation with everything from lower IQ scores to diminishing thyroid hormone levels. Communities across Canada debate fluoridation every few years, a trend that’s existed since fluoridaiton began in Canada.

In recent years, research on humans and rats has proposed a link between fluoride and childhood osteosarcoma in boys, a rare bone cancer that killed Terry Fox and often leads to amputations. The Canadian Cancer Society notes that these claims are heavily contested and require further study. Conflicting research suggests long-time exposure to fluoride may not increase the risk of osteosarcoma. When fluoride is ingested, half the substance is absorbed by the bones and accumulates over time.

In a November referendum in Waterloo, Ontario, 50.3 percent voted against continuing fluoridation. Last week, the Calgary Herald published an editorial calling for an end to fluoridation. The city is considering doing away with its aging fluoridation equipment, which would cost $6 million to replace.

A 2009 Health Canada report found that 43 percent of Canadians use fluoridated tap water. Water quality falls under provincial jursidiction and fluoride usage in Canada varies by region, with Ontario clocking in at almost 76 percent fluoridation, a number that drops to 6.4 percent in Quebec and 3.7 for British Columbians.

Health Canada recommends 0.7 parts per million fluoride to water, the same level now being proposed in the U.S. Toronto’s fluoride level was reduced from 1.2 p.p.m. to 0.8 p.p.m. In 1999, then to 0.6 p.p.m. in 2005.

[Creative Commons Water photograph by Flickr user visualpanic]