HEALTH: Pesticides May Increase Disease in Developing Countries

By IPS Correspondents Reprint | | Print |

Judith Perera

LONDON, Jun 30 1996 (IPS) - The widespread and largely unregulated use of pesticides in developing countries could be contributing to the burden of ill health by weakening the effectiveness of their peoples’ bodily immune systems.

“The effect of pesticides on the immune system has not been monitored until relatively recently,” explains Peter Beaumont, Director of the London-based Pesticides Trust, “but there is now a growing body of evidence to suggest that there is a suppressive effect.”

He explains that preliminary work has shown this effect, especially with respect to the older established families of pesticides such as organophosphates, organochlorines, carbamates and the phenoxy compounds. He adds that regulatory bodies should ensure that test data supplied by pesticide manufacturers include immune system effects.

“But of course this would be impossible in many developing countries where control is minimal.”

A recent detailed study of pesticides and the immune system by the Washington-based World Resources Institute (WRI) identified hundreds of studies which showed that many widely-used insecticides, herbicides and fungicides can suppress normal immune system responses.

Developing countries are especially at risk because a larger proportion of the population still works in agriculture and because pesticide use is growing and is generally very poorly regulated. Farmers lack training and proper equipment for handling the chemicals, points out WRI vice-president Robert Repetto.

Yet people in the developing world are at high risk from any chemical exposure that weakens their immune systems. Infectious and parasitic diseases are still major causes of death and health care is generally inadequate.

It has long been known that exposure to pesticides can cause acute poisoning, birth defects and some types of cancer and test data normally takes this into account. However, immune effects are more subtle and difficult to identify.

Nevertheless the evidence is now substantial and testing should be extended to cover this, Beaumont insists.

Repetto examined epidemiological evidence from the former USSR, Asia and North America. In the former USSR, farmers in areas where pesticide use was heavy showed immune system irregularities such as reduced white blood cells and the presence of antibodies suggesting an auto immune response — a disorder in which the immune system begins to attack organs of the body.

Uzbek cotton farmers exposed to large amounts of chemicals showed increased levels of both infectious and chronic disease compared with people living in unaffected areas.

Other studies showed high mortality rates among Filipino rice farmers exposed to pesticides which rose as pesticide use increased. However their wives and men from neighbouring non- farming areas were not affected in this way.

Native American Inuits in northern Canada are especially at risk as pesticides such as organochlorines accumulate in much of the food that they eat such as fish.

Transported by ocean currents, atmospheric winds and rivers, persistent chemicals accumulate in arctic ecosystems in extremely high concentrations. Most at risk are babies who take in the chemicals from breast milk.

As a result, instead of boosting immunity as it should, breast feeding leads to immune suppression. Compared with bottle-fed babies, breast-fed infants have extremely high rates of infectious disease including meningitis.

Their immune systems are so compromised that they cannot be vaccinated against the usual childhood diseases because they are unable to produce sufficient antibodies.

While pesticide use is no longer increasing so rapidly in developed countries, it is continuing to rise in the Third World. It has almost tripled over the past 20 years in Latin America and is increasing in Asia where rice growing alone accounts for 14 per cent of world pesticide use.

In China pesticide use has doubled over the past decade and now totals around 300,000 tonnes a year. Moreover, many developing countries still allow the use of products which have long been banned in the industrialised states.

“There is now enough evidence linking pesticide exposure to immune system suppression to justify more comprehensive studies to clarify the risks,” says Repetto. “Such studies should be led by the WHO.

Multilateral and bilateral aid agencies should support such research and expand efforts to improve pest management practices.” He points out that a lot of development assistance has been channelled into improving sanitation and health care systems to reduce infectious disease.

“Complementary programmes to eliminate environmental threats to the immune system could be a cost effective method to insure the success of these on-going efforts.”