HONG KONG: Hong Kong residents have become distracted this week by fears of dioxin poisoning, as worry grows about the effects of about 10,000 rounds of tear gas fired across the financial hub over more than five months of anti-government protests.

Many people are steering clear of fresh fruit and vegetables and warning family and friends to wait a week before eating anything that might have been exposed to the gas that has shrouded various neighbourhoods at times over the months.

According to some advice that has spread online, women should avoid becoming pregnant for two years if they have been affected by the agent.

The city government has said it has found no evidence of dioxin poisoning from tear gas, but that looks unlikely to allay the fears, especially, some critics say, as authorities have not fully explained what chemicals are in tear gas.

"Spread this message, avoid eating poisonous fruits, dioxin is extremely toxic, peeling off the fruit skin won't remove the toxin," one online message said this week.

Most fruit in Hong Kong is sourced from a wholesale market in the working-class district of Yau Mai Tei on the Kowloon peninsula, a protest hot spot where police fired volley after volley of tear gas on Sunday and Monday.

Yau Mai Tei is also a stone's throw from Polytechnic University, the scene of some of the most intense clashes between protesters and police last weekend.

On Monday, patients at the nearby Queen Elizabeth Hospital were advised to stay indoors and others to steer clear of its out-patient clinics.

Fruit vendors at the Yau Ma Tei market said business had dropped up to 80% this week.

Some have shut up shop or closed early as customers stay away, but they all shrugged off worries about their fruit.

"All of the fruit that arrives here is boxed, and the fruit offloading hub is six blocks away from Nathan Road. Tear gas cannot travel this far," said a vendor surnamed Li, adding that fresh fruit arrives every day.

"I won't blame the people, they don't understand the process. But it's hard to say how long the impact will last, I can't help it if people believe the rumours."

DEFORMED BABIES?

Online messages and forums also focussed on the effects of tear gas on pregnant women. Some residents say tear gas releases dioxin and cyanide in extremely high temperatures, which could lead to miscarriage or infant deformities.

Doctors say they have been inundated with enquiries.

"One patient asked me whether her baby would be deformed because she inhaled tear gas last week," said obstetrician Kun Ka-yan.

Kun said CS gas, the main component of tear gas, does not directly result in miscarriage or baby deformities, while dioxin and cyanide only affect pregnant women if they are exposed to a large dose, or if the agents contaminate the food chain.

"The problem is the government has not actively explained the components of tear gas and their impact on health," he said.

"People got worried after the online rumours this week."

Secretary for Food and Health Sophia Chan has tried to ease the concerns.

"The Department of Health and Hong Kong Poison Information Centre of Hospital Authority have reviewed relevant medical literature and scientific evidence but have found no literature or scientific evidence on dioxin poisoning cases caused by the use of tear gas," she said.

Chan added, however, it was better to be safe than sorry.

"For the sake of prudence, food suspected to be contaminated or showing abnormality should not be consumed," she said.