Pesticides in fish are a health danger in Asia
Farming communities in South-east Asia, where fish and water plants are on
the daily menu, are at risk of absorbing poisonous substances found in
pesticides. A preliminary risk analysis performed by Alterra of Wageningen
UR and six other international research institutes throws light on some of
the more frightening risks resulting from heavy pesticide use in Thailand
and Sri Lanka. A decision support system has now been developed to manage
pesticide use in these areas.
The calculations made by the researchers indicate that the pesticide
prothiofos occurs in food in concentrations that are sometimes 3000 times
higher than the maximum level allowed in a normal diet. The use of this
organophosphate is banned in a number of countries. Long-term exposure to
organophosphate compounds has a negative effect on the central nervous
system and is thought to be associated with chronic fatigue syndrome. The
researchers stress that more measurements need to be made and chemical
analyses must be done, but the first indications paint a grim picture.
The researchers have discovered that poisonous substances found in a wide
range of pesticides that end up in surface water are also found in
dangerously high concentrations in fish and water plants. They base this
conclusion on information on pesticide use and their preliminary
calculations on the possible effects on health.
The research is part of a broader four-year project for which the EU has
made 900,000 euros available and the Dutch Ministry of Agriculture 85,000
euros. Alterra is working together with the Dutch Agricultural Economics
Research Institute (LEI) and six other research institutes from Portugal,
England, Sri Lanka and Thailand.
One of the Alterra researchers, Dr Paul van den Brink, names various
pesticides that can be dangerous to the human population because they are
absorbed by fish and water plants: “The water mimosa is a aquatic plant
that is eaten a lot in Thailand, and pesticides such as chlorfenapyr are
sometimes found in high concentrations in this plant. This can cause
stomach cramps. Fish containing large amounts of the insecticides EPN and
cypermethrin also have the same effect. Thai people eat a lot of fish; in
the area where we worked, 82 grams of fish a day is a normal amount.