Treatment: Use of methyl bromide as a fumigant
Effective 2 August 2019
Methyl bromide is widely used as a fumigant for timber, agricultural products, empty containers, foodstuffs, seeds, plants, and fresh fruit and vegetables. It is favoured due to its high toxicity to a wide range of insects coupled with its good penetrating ability and speed of action.
The gas is regarded as a safe fumigant for seeds providing the moisture content is not excessively high and fumigation is not repeated.
Methyl bromide is odourless so small concentrations of chloropicrin (tear gas) are sometimes added as a warning agent. However, chloropicrin is very phytotoxic and must not be used for the fumigation of live plants, fruits, vegetables and seeds.
Residues are likely to be greater in commodities with high oil contents such as nuts.
Highly painted, varnished or glazed timber products are believed to inhibit the penetration of the fumigant.
Plastic wrapping does inhibit the penetration of the fumigant.
Methyl bromide is also known to react with materials containing sulphur to produce objectionable odours which may persist even after prolonged aeration.
Products not ordinarily fumigated with methyl bromide are:
butter, lard and fats unless in airtight cans
nuts with high oil content
soybean flour, whole wheat flour, other high protein flours; and baking powders
charcoal and cinder blocks
furs, felts, horsehair articles, feather pillows, rug pads
high rag content writing papers and other high sulphur papers
iodized salt; salt blocks containing sulphur or its compounds
leather goods, particularly kid
photographic chemicals (not camera film or X-ray film), photographic prints and blueprints
silver polishing papers
rubber goods, particularly sponge rubber, foam rubber and reclaimed rubber including pillows, mattresses, rubber stamps and upholstered furniture
woollen, especially angora; soft yarns and sweaters; viscose rayon fabrics
sulphur-based paint and oil artworks