Our government acknowledges that many pesticides are toxic in nature and have to be handled carefully. It regulates their manufacture, import, supply, sale and storage. That is as it should be given how harmful they can be to children and animals and, depending on exposure, to health in general. The mystery, then, is why some products that are under scrutiny elsewhere are available here, and why there is no oversight of the people most likely to come into contact with the chemicals - those who spray them.
The 1962 book Silent Spring, about the dangers of DDT, first raised general concern about pesticides. Only after decades of study can their effects on human health truly be known. Governments have since been ever more stringent with requirements and regularly issue updates about particular products as more research is carried out. The Hong Kong authorities have to keep up to date with developments elsewhere and make the necessary adjustments.
They nonetheless seem unconcerned about a pesticide highlighted by this newspaper on Monday - diazinon, which has been restricted or is under review in Britain and the United States because of data gaps and concerns about its effects on the nervous system. A government spokeswoman said different governments adopted different levels of control. She said a licensing system for pest control companies would impose an unnecessary burden on the trade. This does not appear a responsible position in light of the acknowledgement of the possible harm to health that pesticides can cause.
The Agriculture, Fisheries and Conservation Department publishes information on the safe and proper use of pesticides. That is not enough. Allowing anyone to commercially spray hurts credible and responsible firms. Only people properly trained in the safe handling, storage and application of pesticides and able to identify and manage pests should be allowed to operate. It is not a matter to take lightly.