Did bed bug insecticide kill Chiang Mai tourists?

An independent investigation that concluded a New Zealand tourist died from exposure to a pesticide used to kill bedbugs at a Chiang Mai hotel in northern Thailand “carries little weight”, a local medical expert says.

A toxic substances expert from the Public Health Ministry says he does not believe that a chemical used in insecticides led to the death of Sarah Carter, 23, in February, the Bangkok Post reported.

Ms Carter died and her friends Emma Langlands, 23, and Amanda Eliason, 24, became gravely ill while on holiday in Chiang Mai.

A total of seven tourists are believed to have died in similar circumstances in the region this year.

UK pensioners George Everitt, 78, and his wife Eileen, 73, were found dead in their hotel room while holidaying in Chiang Mai on February 19.

Their deaths came less than two weeks after that of Ms Carter, who had been staying at the same hotel.

Thai authorities said Mr and Mrs Everitt had suffered heart attacks within minutes of each other, despite family members in Britain insisting they had no history of heart problems.

Traces of the insecticide chlorpyrifos were found in samples New Zealand television show 60 Minutes took from the women’s hotel room and had independently tested.

United Nations scientist Ron McDowall said there was a strong likelihood Ms Carter died from excessive exposure to the substance, which causes identical symptoms to those suffered by the trio as well as several other tourists who died after staying at the hotel.

Chiang Mai Public Health Office deputy chief Surasing Visaruthrat told the Dominion newspaper that authorities had not ruled out all possible causes of the deaths.

Checks had been carried out when the three women were admitted to hospital and no trace of insecticides had been found, he said.

The chemical is not banned in Thailand but approval is needed before it is imported or exported.

An autopsy performed by Maharaj Hospital found no toxic substance residue and doctors suspected Ms Carter died from food poisoning, according to a Chiang Mai police report.

Thai officials suggested eating toxic seaweed in meals bought at a nearby night market was the cause of her death.

In an undercover investigation, New Zealand’s TV3 network sent a reporter to the hotel and took swabs from Ms Carter’s room, which were returned to New Zealand for analysis.

Officials in Chiang Mai claim the tourists’ deaths were nothing but coincidence, and have described them as “bad luck for that hotel”.