DUBAI, United Arab Emirates — Water authorities in the emirate of Abu Dhabi are working to rid drinking water of elevated levels of bromate, a chemical compound thought to cause cancer in humans, health experts told The Associated Press.

Bromate can appear when drinking water is produced from salty sources, and in the United Arab Emirates and other desert countries, desalination of sea water is the dominant process for for potable water.

Local and international officials stressed that the risk of cancer from bromate is probably very low -- but not fully understood. No known cases of cancer in humans have been linked to bromate in water, experts said.

"We think that for the moment, there isn't an immediate threat to health," said Houssain Abouzaid, a Cairo-based water quality expert with the World Health Organization familiar with the bromate problem in the Middle East.

"But something needs to be done. It's a long term problem, something that builds up over years," he said.

Tests of drinking water samples from the Abu Dhabi Water and Electricity Authority, which serves the Abu Dhabi emirate, have shown bromate levels around 10 times the WHO's recommended guidelines, according to Global Water Intelligence, an industry newsletter that reported the contamination in June.

Nick Carter, who heads Abu Dhabi's Regulation and Supervision Bureau, confirmed the findings and said the eight private plants that produce water for the emirate have been taking steps to reduce bromate below the WHO threshold by Jan. 1.

"It's not a big problem and within six months of finding the cause of it, we've solved it," Carter said.

The bromate was introduced into the water after plants switched from treatment with volatile chlorine gas to using seawater-based chlorine, Carter said. Some plants are returning to using chlorine gas until a better treatment solution can be found, he said.

"It was such a dangerous gas to move around. There was a desire to move away from that," Carter said. "But in so doing, we created this bromate problem."

At the levels reported by the newsletter -- around 100 parts per billion -- bromate levels in water from the Abu Dhabi plants would surpass even WHO's previous guidelines of maximum levels of 25 parts per billion. The organization tightened that standard last year to 10 parts per billion, Abouzaid said.

In Britain last year, bottled water sold by the Coca Cola Co. that was found to contain around 25 parts of bromate per billion was recalled from store shelves.

Bromate has cropped up in drinking water elsewhere in the Gulf and around the world, said Joseph Cotruvo, a water quality consultant for the WHO and former director of drinking water standards and risk assessment at the U.S. Environmental Protection Agency. Cotruvo declined to name countries.

But Abouzaid said authorities in Kuwait and Oman were looking into the possibility that the chemical was present in their drinking water.

Governments in the region have been tightlipped about the contamination, which WHO experts said was widespread.

The other six emirates that make up the United Arab Emirates have not provided requested data on bromate levels, Carter said.

Authorities in Oman and Dubai did not respond to requests for comment. A water expert in Kuwait said he was unable to retrieve bromate test results from that country's water authority.

Natural bromide in seawater can be converted to bromate when technicians produce their own chlorine by electrolyzing seawater and using it as a disinfectant, Cotruvo said.

Bromate also appears when saline water is treated with ozone, a disinfectant especially popular with producers of bottled water.

The chemical can be difficult to identify and to remove from water supplies, Abouzaid said.

Abouzaid and Cotruvo stressed that there was no need for the public to stop drinking tap water as long as water authorities were working to reduce bromate levels.

A university study last year in Greece found bromate in ozone-treated groundwater typically used by small firms selling bottled water.

The Coca Cola Co. recalled 500,000 bottles of its Dasani bottled water in Britain last year after finding elevated levels of bromate. Coke blamed the bromate problem on its practice of adding calcium chloride to the treated tap water it sold as Dasani. Coke's Dasani water sold in the United States is also produced from tap water, but is not treated with calcium chloride, the company said last year.

After the Dasani recall, Britain's Food Standards Agency said bromate "is a chemical that could cause an increased cancer risk as a result of long-term exposure, although there is no immediate risk to public health."

Cotruvo and Abouzaid noted that bottled water, which is subject to the same contamination, was probably no safer than generally high quality tap water in the Gulf.

Bromate occurrence in desalinated water can be reduced if utilities change disinfection methods. By using chlorine from sources that do not contain bromide, bromate levels can be cut to within WHO guidelines, Abouzaid said.

Source: Associated Press