SPRI Home About SPRI

Dimethoate

Fosfamid, Cygon

SPRI Emission Reporting Threshold
0.01 Kg/yr Pollutant Emissions to Water
0.01 Kg/yr Pollutant Emissions to Waste Water
0.01 Kg/yr Pollutant Emissions to Air
Disclaimer
This sheet is a generic summary, designed to give the reader a basic level of background information about the substance in question. Great care has been taken to represent as effectively and correctly as possible the broad range of (not necessarily consistent) information which is available from a variety of sources. The reader must accept therefore that this sheet has no legal status and cannot be relied upon in any legal proceedings. SEPA disclaims any responsibility or liability whatsoever for errors and omissions in this sheet.
What is it?
Pure Dimethoate is colourless crystals, which have a faint chemical smell. It often contains impurities, which give it a grey colour. It melts at 52 degrees celsius. It dissolves in water to give a stable solution. Acidic solutions are similarly stable, but alkaline solutions are unstable. Dimethoate is highly soluble in organic (carbon-containing) solvents.
What is it used for?
Dimethoate is an organophosphorus pesticide. It has been widely used as an insecticide on a range of crops and fruit trees. It can also be used to control domestic insects such as houseflies. In common with other organophosphorus pesticides, Dimethoate works in a similar way to chemicals developed as "nerve gas" during the second world war.
Where does it come from?
Releases of Dimethoate will occur during its manufacture, transport, storage and use as an insecticide. There are not thought to be any natural sources of Dimethoate to the environment.
How might it affect the environment?
Dimethoate is very toxic to non-target insects such as bees and also to birds and aquatic organisms. It may also harm other wildlife and livestock. There is also concern that exposure to Dimethoate may interfere with the hormone systems - that it is an "endocrine disruptor". When applied to crops, Dimethoate does not bind significantly to soils and so will evaporate into the atmosphere, run off into surface water bodies and also seep into groundwaters. It is broken down in air within a few days, whereas breakdown in soils and water can take months. Dimethoate does not accumulate in the environment. It is not considered likely that Dimethoate pollution has any effects on the global environment.
How might exposure to it affect human health?
Dimethoate exposure mainly occurs in the occupational environment. Dimethoate can enter the body either by inhalation of air containing dimethoate, accidental ingestion of dimethoate or ingestion of contaminated food, or by dermal contact with dimethoate. Inhalation of air containing elevated levels of dimethoate can lead to a range of health effects including breathing difficulties, headache, dizziness, tiredness, slurred speech, blurred vision, a lack of coordination, sweating, slow or rapid heart beat, convulsions, incontinence and in extreme cases unconsciousness and death. Exposure to dimethoate over long periods of time can cause similar symptoms as those described above and may also lead to impaired memory, depression, irritability, confusion and insomnia. Ingestion of dimethoate can cause vomiting, diarrhoea, abdominal pain, faecal incontinence and effects similar to those for inhalation. Dermal contact with dimethoate can cause sweating. Absorption of large quantities through the skin may lead to effects similar to those for inhalation and ingestion. Eye contact may cause irritation. The International Agency for Research on Cancer has not designated dimethoate in terms of its carcinogenicity. However, exposure to dimethoate at normal background levels is unlikely to have any adverse effect on human health.
What steps are being taken to limit the potential impacts?
Releases of Dimethoate are controlled through the Food and Environmental Protection Act (FEPA 1985) and the Control of Pesticides Regulations (COPR 1986). It is also regulated through the UK Pollution, Prevention and Control (PPC) Regulations and the UK Surface Waters (Dangerous Substances) Regulations (SI 1997/2560). European Directives regulating levels of Dimethoate include that concerned with the pollution of the aquatic environment (76/464/EEC). At an international level, Dimethoate is listed as a candidate substance under the Helsinki and OSPAR Conventions, which protect the marine environment of the Baltic Sea and north-east Atlantic Ocean respectively.