The growing threat from pesticides

Date:06-03-2011

The environmental impact of pesticides is often greater than what is intended by those who use them. Over 98% of sprayed insecticides and 95% of herbicides reach a destination other than their target species, including non target species -- air, water, bottom sediments, and food. Pesticide contaminates land and water when it escapes from production sites and storage tanks, when it runs off from fields, when it is discarded, when it is sprayed aerially, and when it is sprayed into water to kill algae.

Pesticides can contribute to air pollution. Pesticide drift occurs when those suspended in the air as particles are carried by wind to other areas, potentially contaminating them. Pesticides that are applied to crops are volatile and may be blown by winds into nearby areas, potentially posing a threat to wildlife.

In the United States pesticides were found to pollute every stream and over 90% of wells sampled in a study by the US Geological Survey. Pesticide residues have also been found in rain and groundwater. Studies by the UK government showed that pesticide concentrations exceeded those allowable for drinking water in some samples of river water and groundwater.

Many of the chemicals used in pesticides are persistent soil contaminants, whose impact may endure for decades and adversely affect soil conservation. The use of pesticides decreases the general biodiversity in the soil. Not using the chemicals results in higher soil quality.

Pesticides inflict extremely widespread damage to biota, and many countries have acted to discourage pesticide usage through their biodiversity action plans. Animals may be poisoned by pesticide residues that remain on food after spraying, for example when wild animals enter sprayed fields or nearby areas shortly after spraying.

Pesticides can enter the human body through inhalation of aerosols, dust and vapor that contain pesticides; through oral exposure by consuming food and water; and through dermal exposure -- direct contact of pesticides with skin. When pesticides are sprayed onto food crops, especially fruits and vegetables, they secrete into soils and groundwater which can end up in drinking water, and pesticide spray can drift and pollute the air. Exposure to pesticides can range from mild skin irritation to birth defects, tumors, genetic changes, blood and nerve disorders, endocrine disruption, and even coma or death.

In recent decades, the indiscriminate use of agricultural pesticides has created very serious health and environmental problems in many developing countries. One to five million farm workers are estimated to suffer pesticide poisoning every year according to WHO, UNEP and at least 20,000 die.

Researchers at the Institute of Development Policy Analysis in Bangladesh found banned and suspect pesticides among the 12,000 tonnes imported into the country last year -- a three-fold increase over the last decade. Suppliers continue to sell many chemical and also 12 particularly controversial pesticides dubbed the "dirty dozen" by activists campaigning worldwide to stop their manufacture. But gullible and illiterate farmers are persuaded by glib sales talk at promotional camps, and through incentive schemes, to buy new unregistered formulations that promise to protect crops against pest attacks and disease.

In a recent survey of 820 boro (winter rice), potato, bean, eggplant, cabbage, sugarcane and mango farmers in Bangladesh, more than 47 per cent of farmers were found to use more pesticides than needed to protect their crops.

With only four per cent of farmers formally trained in pesticide use or handling, and over 87 per cent freely admitting that they used little or no protective measures while applying pesticides, overuse is potentially a very threatening problem to farmers' health as well as the environment in this country. Thus, in Bangladesh there is an urgent need to actively promote safer pesticide use and hygienic practices among people who handle these substances.

Research findings also highlight the need for policymakers to design effective, targeted outreach programmes that address pesticide risk, safe handling, and protection. The approach should ideally be participatory, with a view to addressing the most dangerous information gaps. Another important finding from Bangladesh is that specific crops and geographic locations experience more overuse than others. For the most measurable results, interventions should focus on these crops and regions.

Information on how pesticides affects health is quite limited in Bangladesh. Farmers in Bangladesh are often unable to distinguish the symptoms of pesticide poisoning from other health problems. This suggests that regular medical checkups and blood tests should be conducted for those who handle highly or moderately toxic pesticides. Also, farmers should be encouraged to switch to lower-hazard pesticides and use protective gear to reduce individual health risks.

Even when individual farmers are careful, pervasive contamination from others' pesticide use and persistent pesticide residues in local water, air and soil may pose significant health risks. Collective measures, therefore, can be an important complement to individual actions.

Chemically polluted runoff from fields has contaminated surface and ground water, damaged fisheries, and destroyed freshwater ecosystems in Bangladesh. A significant part of such contamination is the result of unregulated pesticide use.

But a great deal of positive changes can occur with Integrated Pest Management (IPM) and conventional techniques. IPM comprises a range of approaches, from carefully targeted use of chemical pesticides to biological techniques that use natural parasites and predators to control pests.

Results from Bangladesh suggest that the productivity of IPM rice farming is not significantly different from the productivity of conventional farming. Since IPM reduces pesticide costs with no accompanying loss in production, it seems to be more profitable than conventional rice farming.

Interview results also suggest substantial health and ecological benefits. However, collective adoption of these methods is a must. Neighbours' continued reliance on chemicals to kill pests will also kill helpful parasites and predators, as well as exposing IPM farmers and local ecosystems to chemical spillovers from adjoining fields.

Source: The Financial Express