DDT – Environmental Levels and Human Exposure

Air: when DDT is sprayed, any that fails to reach its target can drift away. Vaporisation from treated fields can be detected for more than 6 months after application. It can drift up to 1000 km

Environmental levels:

–Nonagricultural areas: < 1 – 2.4 ng m^-3

–Agricultural communities: 1 – 22 ng m^-3

–Communities with anti-mosquito programmes: up to 8.5 μg m^-3

Water: highest level recorded 0.84 mg/L (USA: 1964 – 1968)

–Over 90% of DDT in the general population comes from food

Acute exposure: Acute toxicity of DDT is high in insects and lower in mammals. Large doses causes focal necrosis of liver cells in several species. It increases liver tumours in mice

Human exposure: Can affect the nervous system. Acute intoxication by DDT can lead to symptoms such as nausea, vomiting, paraesthsia, dizziness, confusion, tremors and in severe cases convulsions

All the symptoms are rare

No evidence that DDT has reproductive or teratogenic effects

All epidemiological studies in humans have indicated that DDT is not carcinogenic