The Agriculture, Fisheries & Conservation Department has ordered the recall of 11 brands of mosquito coils after tests found that the products contain an active ingredient that is not registered in Hong Kong.

The tests, conducted jointly by the department and the Consumer Council, showed that 11 of 19 samples contained the unregistered ingredient octachlorodipropyl ether, or S-2.

The department has almost completely retrieved nine of the 11 brands of mosquito coils confirmed to have S-2 from the market, and must complete the recall of the remaining two by the end of the month.

Under the Pesticides Ordinance, only registered pesticides can be imported, manufactured, sold or supplied in Hong Kong.

According to the World Health Organization and other overseas regulatory bodies, there has been limited research on the safety of S-2 in mosquito coils. There is no conclusive evidence that using S-2-containing mosquito coils can cause human cancer.

An overseas report restricted to a laboratory study suggests burning S-2 might release a carcinogen known as BCME. The study also mentions that BCME was unstable in air and its concentration was difficult to detect accurately.

In another test, the body condition of rats in separate environments with burning mosquito coils with and without S-2 showed no differences.

New mosquito coils offered without S-2

Some suppliers have already introduced new mosquito coil formulations without S-2 to replace the old stocks in the market. The new products will be submitted to the AFCD for testing and approval before their sale on the market, with packaging that specifies the absence of S-2 for easy identification.

Both the Consumer Council and the AFCD advise consumers to use mosquito coils without S-2 to play safe, since there are alternatives available in the market. The public can dispose of S-2 mosquito coils as ordinary household refuse if they have any left.