Phosphine is a vitally important fumigant used in the UK for the control of burrow living vertebrate pests (rabbits, rats and moles) and a wide range of invertebrate pests which infest stored food commodities.
Pure phosphine is a highly toxic colourless, tasteless and odourless gas applied as an easily handled solid known as Metal Phosphide; aluminium phosphide and magnesium phosphide are the metallic phosphides used and these react with water vapour in the environment to generate the active ingredient phosphine (Hydrogen Phosphide PH3); when freshly generated from solid formulations the resultant gas will contain impurities (substituted phosphine and disulphide) which gives it a garlic type smell and can serve as a warning to its presence in the atmosphere at very low concentrations. Phosphine may also ignite in air at concentrations above 18,000 parts per million.
Phosphine’s high toxicity makes it the most toxic substance used for controlling pests in the UK and, as such, deserves special attention to protect people and non-target animals from malicious or irresponsible use, storage, transport and disposal.
It’s use is governed under the Food and Environment Protection Act 1985 and the Control Of Pesticides Regulations 1986 and its supply to end users restricted. There is now a requirement for users to be certified in the use of the product under the Plant protection (sustainable use) regulations 2012. This will mean that:
Following consultation with affected parties, namely the distributors, trainers, pest control, farming and game keeping industries it is clear that there is a cross-industry consensus that recognises the need to maintain the product for controlling the pests for which it is currently approved and also to improve the level of stewardship without being anti-competitive with its supply.