Bromomethane

Long-term toxicity to fish

Description of key information

According to Commission Directive 96/12/EC, a chronic toxicity study must be carried out unless it can be justified that continued or repeated exposure of fish is unlikely to occur. Methyl bromide is intended as a soil and space fumigant. Where methyl bromide is intended as a space fumigant it is highly unlikely to come into contact with surface water unless due to leakage from the building/container. 
Where methyl bromide is used as a soil fumigant the application involves incorporation of the product into the soil matrix. Methyl bromide is never applied directly on to surface water. Furthermore, methyl bromide is applied once per season prior to planting. It is proposed that for this case continued or repeated exposure of fish, and hence chronic toxicity to fish from methyl bromide is unlikely to occur.
Furthermore, methyl bromide does not leach readily from treated areas covered with plastic sheeting (sheeting in place usually for 3-4 days after application). The half-life(t½) of methyl bromide in soil under aerobic conditions is 1.95 days. The soil is thus, covered for 1.5 to 2 times the half-life of methyl bromide in soil thereby reducing the possibility of it being flushed out of the soil.