UN alarm at rogue pesticides

Pesticides are used for controlling diseases such as malaria

The United Nations has warned that about 30% of pesticides marketed in the developing world contain toxic substances which pose a serious threat to human health and the environment.

The rogue pesticides contained chemicals either banned or severely restricted elsewhere in the world, or concentrations of chemicals which exceeded international limits.

Scientists linked one common pesticide with Parkinson's

The problem was particularly serious in sub-Saharan Africa, where regulation was generally weak, said two UN agencies in a joint statement.

The Food and Agriculture Organisation (FAO) and the World Health Organisation (WHO) urged governments to make legally-binding the voluntary standards specified by the UN.

Pesticides in developing countries are used both in agriculture and for public health, for instance in the control of insects that spread malaria.

Pesticides costing about $3bn were sold to developing countries last year, out of a global market of $32bn.

Possible causes of low quality of pesticides can include both poor production and formulation, and the inadequate selection of chemicals.

But poor quality labelling and packaging was also blamed.

Brain damage fear

The UN said: "The labelling, often written in improper language, fails to provide data on the active ingredient, application, date of manufacture and safe handling of the chemical."

Pesticides came in for attack last year when it was found that one commonly in use, Rotenone, caused symptoms similar to Parkinson's disease when small amounts were injected into rats over time.

Regulation is weak in parts of Africa

It added weight to theories that repeated exposure to low levels of agrochemicals may also be causing cumulative damage to the human brain.

Scientists also found that pesticides encourage potentially dangerous bacteria to thrive on some crops.

And they warned that people who eat raw fruit and vegetables such as strawberries, raspberries and lettuce could be at risk.

New Scientist magazine reported that the researchers, from University of Manitoba in Winnipeg, carried out research after a rise in reported cases of food poisoning caused by fresh produce.