Introduction
Effects on Humans
Effects on the Aquatic Environment
Monitoring Techniques and Standards
Safety Cards
Links

Introduction

*IARC: International Agency for Research on Cancer.

DDT is an organochlorine pesticide that has been used as an insecticide in agriculture and to combat insect vectors of diseases such as malaria and typhus. DDT is one of the earliest and most well known pesticides, and it was widely used until legislative restrictions were imposed after environmental impairments were manifested. This has led to a widespread contamination of water and soil resources and resulted in serious health effects in animals. Although banned in many countries, DDT continues to be used for residual indoor spraying in a number of countries.

Because of it's effectiveness at killing insects with few acute effects on humans, DDT had been a mainstay of many countries' fights against malaria, a disease that is a growing threat to health in much of the world. For this reason, the World Health Organization (WHO), while supporting an ultimate phase-out, continues to endorse the use of DDT for indoor residual application in government-authorized public health campaigns. (WFPHA, World Federation of Public Health Associations, 2000).

For most populations, the primary route of exposure to DDT and its metabolites is through food. DDT is readily metabolised into a stable and equally toxic compound, DDE. DDT and DDE are fat-soluble and are stored in adipose tissues of humans and animals. They break down very slowly, and are released primarily to urine and breast milk. DDT and its metabolites have been found in virtually every breast milk sample tested, including samples taken in tropical areas of Mexico. In many countries where the pesticide is still in use, levels exceed FAO/WHO ADI standards (0.01 mg/kg bw, 2000); concentrations of DDE are four-to five fold higher in mothers milk of Inuit women in northern Quebec compared with populations from southern Canada. (WFPHA, 2000).

Effects on Humans

A rise in reproductive abnormalities in both humans and wildlife over the last 20-40 years has caused some scientist to look for environmental factors that may be influencing reproductive capacity. DDT and its metabolites are considered to be environmental oestrogens. In a study in India, a group of men who worked with DDT was found to have decreased fertility, and a significant increase in still births, neonatal deaths and congenital defects among their children. Israeli men with unexplained fertility problem were also found to have high blood levels if DDT. (WFPHA, 2000).

Effects on the Aquatic Environment

Adverse health effects of DDT in animals include reproductive and developmental failure, possible immune system effects, and the widespread deaths of wild birds after DDT spraying. As is the case with many organochlorine insecticides, a major target of acute DDT exposure is the nervous system. Long term administration of DDT has brought about neurological, hepatic, renal and immunologic effects in animals. Research has shown that DDT prevents androgen from binding to its receptor thereby blocking androgen from guiding normal sexual development in male rats and resulting in abnormalities. Evidence has been found in alligators in which hatchlings from DDE-painted eggs are sexually indeterminate; possessing both male and female reproductive characteristics. (WFPHA, 2000).

In laboratory cultures of whole phytoplankton from the Caspian and Mediterranean seas, DDT reduced primary production by as much as 50% at a concentration of 1 ppb. Marine fish appear to be very sensitive to DDT: the 96 h LC50 for it ranges between 0.4 and 0.89 micrograms/l for a variety of teleosts. Bivalve molluscs, on the other hand, with their ability to concentrate organochlorine pesticides without coming to harm have a 96 h LC50 greater than 10 mg/l. (Clark, 1997).

Long range atmospheric transport of DDT into the northern countries, including the Arctic, is well documented, DDT has been detected in Arctic air, soil, snow and ice, and virtually all levels of the Arctic food chain. Many studies indicate that bottom sediments in lakes and rivers act as reservoirs for DDT and its metabolites. Despite a twenty-year ban in the U.S., It is still found concentrated in soils and freshwater sediments. Aquatic vertebrates such as fathead minnow and rainbow trout have also been found to contain DDT.

Monitoring Techniques and Standards

The HSDB, Hazardous Substances Data Bank: type DDT

This site reports a full list of information on the substance as: Human Health Effects, Animal Toxicity Studies, Environmental Fate & Exposure, Environmental Standards & Regulations, Chemical/Physical Properties, Chemical Safety & Handling, Occupational Exposure Standards, Laboratory Methods, Synonyms and Identifiers.

Toxicology report with toxicity data from the Vermont Safety Information Resources, Inc.

This site provides a list or toxicity tests results, references for toxicity literature reviews, USA standards and regulations, occupational exposure limits in different states all over the world, and reference to NIHOSH, National Institute for Occupational Safety and Health, analytical standard methods.

Safety Cards

ICSC, International Chemical Safety Cards European Union version

The International Occupational Safety and Health Information Centre (CIS) access to
International Chemical Safety Cards: two pages data sheets on pure substances from the ILO/WHO/UNEP International Program on Chemical Safety (IPCS).

ICSC, International Chemical Safety Cards U.S. National version

The National Institute for Occupational Safety and Health (NIOSH) access to
International Chemical Safety Cards.

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