Restrictions on the use of the insecticide DDT to combat malaria have often been attacked by a group of campaigners who say the limitations are based on unsound science and cost lives in the developing world.

Now those campaigners have told a US Senate committee that lobbying for the restrictions may be commercially motivated.

DDT was once widely used on farms, but its use in agriculture dropped sharply from the 1970s because of concerns about its effect on the food chain, particularly on birds of prey. More recently, with malaria spreading in developing countries, some such as South Africa have sprayed DDT indoors to kill mosquitoes.

But they face obstacles. The World Health Organisation (WHO) prefers using bed nets to DDT. And the European Union has warned Uganda about the risks to its food exports if it uses DDT.

"While the EU fully acknowledges the urgent need to control malaria in Uganda, we are concerned about the impact the use of DDT might have on the country's exports of food products to the EU," the European Commission's Uganda delegation said last year.

In congressional testimony, Richard Tren of the Africa Fighting Malaria campaign said lobbying for restrictions might have commercial motives. Mr Tren cited an email to health academics from Gerhard Hesse, business manager for "vector control" - eliminating carriers of disease - for Bayer CropScience, cautioning against DDT.

Bayer manufactures alternative insecticides to DDT, which are generally more expensive. In the email, seen by the FT, Mr Hesse said: "We fully support EU to ban [sic] imports of agricultural products coming from countries using DDT." He said such a ban reflected the danger of DDT leaking into the agricultural system and ending up as residues in food.

But Mr Hesse, who sits on the partnership board of the WHO's "Roll Back Malaria" coalition, also admits: "DDT use is for us a commercial threat."

He argues that the commercial threat is not dramatic because of DDT's limited use, saying it is "mainly a public image threat".

Mr Tren told the Senate committee: "We fear that commercial entities such as Bayer . . . are using bad science and fear about DDT in order to advance their own particular interests."

In a statement, Bayer said Mr Hesse meant to refer purely to DDT for crop use. "Bayer CropScience rejects any interpretation that the company would support the EU move to ban imports of agricultural products coming from countries using DDT for company specific competitive reasons," it said.

"Gerhard Hesse's statement in this respect was written in a way which might lead to wrong conclusions. It does not reflect the actual opinion of Mr Hesse and of Bayer CropScience."

The EU said it did not ban food imports from countries using DDT but required them to comply with maximum residue limits.

Financial Times