Critics raise red flag over fluoride in tap water

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Critics raise red flag over fluoride in tap water

MARTIN MITTELSTAEDT

 

From Friday's Globe and Mail

 

http://www.theglobeandmail.com/servlet/story/RTGAM.20071123.wlfluoride23/BNStory\

/specialScienceandHealth/?cid=al_gam_nletter_newsUp

 

November 23, 2007 at 9:27 AM EST

 

Nearly a half-century after water fluoridation became widespread, a

small but growing number of medical officials and environmentalists

are again raising concerns over the practice.

 

Recent research is suggesting that fluoride may be connected to a

number of serious conditions, including the development in teenage

boys of osteosarcoma, the rare bone cancer that killed Canadian icon

Terry Fox, reduced intelligence levels in children, and impaired

thyroid function.

 

In Waterdown, Ont., a suburb of Hamilton, Cindy Mayor has approached

her city council and asked that it stop fluoridation for the area's

500,000 residents. " Here we are, mass-medicating with a drug, " she

says. The activist frets that fluoridation could be one reason for the

growing number of people being treated for lowered thyroid hormone

levels.

 

She isn't alone in worrying about fluoride, placed in many municipal

water supplies to make teeth more resistant to decay.

 

 

While those complaining about fluoride were often portrayed as a

kooky fringe - typified by the 1964 movie classic Dr. Strangelove, in

which a demented U.S. general feared fluoridation was a communist plot

- fluoride criticism has recently gone mainstream.

 

Although the research linking the chemical with serious conditions is

disputed, critics of fluoridation say that at the least it indicates a

review of the practice needs to be conducted.

 

A review is even more pressing, in the view of critics, because

scientists now believe that the main protective action from fluoride

does not come from ingesting the chemical, with the teeth absorbing it

from inside the body, but from direct absorption through topical

application to teeth.

 

This means swallowing water is a far less effective way to fight

cavities than brushing with fluoridated toothpaste. That may explain

the steep decline in cavity rates observed in industrialized countries

since the 1970s, irrespective of whether they fluoridate water. Almost

all of Europe does not, and yet has seen a sharp reduction in dental

caries.

 

" I think there is a much broader understanding that there might be

some legitimate concerns with fluoride, " said Richard Wiles, executive

director of the Washington-based Environmental Working Group, a public-

interest group that has been lobbying the U.S. National Institutes of

Health to provide a second opinion on fluoridation.

 

About 13.5 million Canadians, or about 43 per cent of the population,

live in communities with fluoridated tap water, but almost no

fluoridation is done in British Columbia or Quebec, according to

Health Canada.

 

The EWG worries that the public is being overexposed to fluoride, and

says water is the easiest source to eliminate.

 

Fluoridation is based on research from the 1940s, and Mr. Wiles

contends that it wouldn't be able to pass a modern risk assessment

used for drugs or pesticides.

 

" We took a look at the science and it was really apparent to us that

the current levels of fluoride exposure were unsafe, " he said.

 

The view on fluoride's potential downside is rejected out of hand by

Health Canada, as well as the Canadian Dental Association.

 

" The fluoridation of drinking water supplies is a well-accepted

measure to protect public health that is strongly supported by

scientific evidence, " Health Canada said in an e-mailed statement.

 

Nonetheless, the department said it is currently studying the recent

scientific findings and may adjust the amount it recommends for water.

 

The Canadian Dental Association also endorses fluoridation. " It's

among the greatest public-health measures that has ever been put in

place, right up there with vaccination, " said Darryl Smith, president

of the association.

 

Dr. Smith worries that if fluoridation critics have their way, it will

lead to a loss in the hard-won gains against tooth decay. Currently,

about half of the children in Canada younger than 11 don't have

cavities.

 

Although health authorities are confident fluoridation is a good idea,

they haven't been very good at picking the optimum dose.

 

Many jurisdictions have, with little fanfare, recently cut the amount

they add, to minimize chances that children will get dental fluorosis,

or mottled teeth.

 

The cuts have been substantial enough to suggest that previous levels

to which the public was exposed for more than three decades were too

high. Toronto's drinking water, after several reductions, now contains

half the fluoride it did before 1999, while the province of Quebec cut

the recommended amount by 42 per cent in 2004.

 

Fluorosis, if severe, causes unsightly staining of teeth, but in mild

cases the result is white streaking that many dentists consider

cosmetic. During the 1990s, anywhere from 20 per cent to 75 per cent

of children were afflicted in fluoridated areas.

 

Both Toronto and Quebec fluoridate below the level Health Canada

believes is optimum: 0.8 to 1 part per million fluoride to water.

Toronto is at 0.6 ppm.

 

Among the recent studies, the most worrisome is the possible

association with childhood osteosarcoma.

 

The disease, the cause of which is unknown, is fatal in about one-

third of cases and almost always leads to amputations.

 

 

The research indicates that fluoride exposure among boys, but not

consistently among girls, during a critical period of bone growth from

age 5 to 10 makes them more susceptible to the bone cancer during

their teenage years.

 

Scientists are on the lookout for effects on bones, because they

absorb half the fluoride people ingest.

 

A paper outlining the finding was published in 2006 in the journal

Cancer Causes & Control and produced by Harvard University

researchers.

 

Researchers found that boys aged 6 to 8 who were exposed to more

fluoridated water were about four times more likely to develop the

cancer than those exposed to lower levels. The researchers called

their results " remarkably robust. "

 

 

Although similar findings in young male rodents have been seen in

laboratory experiments, other studies that investigated lifetime human

exposure to the chemical did not detect any association with

osteosarcoma.

 

The EWG's Mr. Wiles said these findings are the kinds of research

clues that should cause governments to consider listing the chemical

as a probable carcinogen.

 

In its statement, Health Canada says it wants to see whether further

research confirms the cancer finding before taking action. " The

findings of the study are in contradiction with the majority of

current science, " it said, although it said health authorities around

the world " have taken seriously the suggestion that fluoridation might

increase bone cancer rates. "

 

Also worrisome are four studies in China, published in scientific

literature from 1996 to 2007, that found a strong association between

water with high fluoride levels and sharply reduced IQs in children.

 

Some parts of China have water naturally rich in fluoride and the

chemical was not deliberately added, as it is in Canada.

 

Although the concentrations that led to the reduced intellectual

functioning were far higher than found in Canada, the studies weren't

designed to discover whether neurological effects occurred at the

lower levels typical of the West.

 

Fluoride has also been found to disrupt normal thyroid hormone

functions. There are concerns that fluoride exposure may be associated

with hypothyroidism, a condition of lowered thyroid hormone levels.

Those with the illness often experience depression, fatigue and weight

gain.

 

Hardy Limeback, head of protective dentistry at the University of

Toronto and a former advocate of fluoridation, is alarmed by these

studies.

 

" We don't know what the health implications are of a lifetime exposure

to fluoride in drinking water, " he says.

 

If fluoridation is ended, it may lead to a modest increase in tooth

decay, which Dr. Limeback estimates at one extra filling in every

fifth child. Given the emerging data on its possible risks, he says,

this would be a small price to pay.

 

Ms. Mayor in Waterdown isn't waiting for Health Canada to complete its

study of the new research. She doesn't drink or cook with tap water,

and instead buys distilled water that has had fluoride removed.

 

Fluoride primer

 

Researchers hit upon adding traces of fluoride to water after

observing that people living in areas with drinking water naturally

rich in the element had lower cavity rates.

 

Fluoridation is primarily done in Canada, the United States and

Australia, but almost nowhere else in the world. Western Europe and

Japan have almost no fluoridated water supplies.

 

Small amounts of fluoride make teeth stronger so they resist decay

better. Too much fluoride causes teeth to be mottled.

 

A typical big city that fluoridates will spend about $1 per resident

each year to add the chem- ical to drinking water supplies.

 

Although fluoridation has been practised for nearly half a century, it

has always been controversial. Critics contend that if fluoride had to

pass a modern assessment for a new drug, it would flunk.

 

But health authorities insist that fluoridation is a good thing and

that the benefits of better oral health outweigh potential risks.

 

Once fluoride is added to water, it isn't easy to get out. It can't be

captured through simple filtering devices. It can be removed through

reverse-osmosis filters or through distilling.

 

Many bottled waters don't contain a lot of fluoride, but some are rich

in it. Those worried about fluoride should check the labels.

 

Martin Mittelstaedt

 

*****

 

Fluoride facts

 

Fluoridation practices vary widely around the world and in Canada.

Most of Europe doesn't fluoridate, and practices vary across the

country. There are no national figures to show whether cavity rates

differ substantially as a result of fluoridation.

 

 

Real knowledge is to know the extent of one's ignorance.

Confucius