Mr. Charles Broley, a retired banker from Winnipeg was a naturalist banding Bald Eagles in Florida and was the first to suggest a relationship between DDT use and the decline of the bald eagle population. After DDT was discontinue the Eagle population started to recover.
DDT and other dangerous chemicals may still be found in other parts of the world.
Travelers to developing countries must be made aware that restrictions on chemicals may be different so they may be able to purchase insecticides that are no longer used in North America. Be careful to only consume fruits and vegetables that are unlikely to have pesticide or herbicide resides.
Winnipeg is the only major city in Canada with an ongoing Malathion nuisance-adult-mosquito-control program
Malathion is an organophosphate insecticide which binds irreversibly to cholinesterase.
Malathion had been widely used in other cities but gradually abandoned.
Its use in Winnipeg is to eliminate nuisance mosquitoes but we do not spray to prevent West Nile Virus (WNV).
Humans and animal share enough chemistry with insects that we are also affected by organophosphates.
The Malathion Health Resource page http://www.chem-tox.com/malathion/research/
written by Florida doctors, reports health problems with malathion.
High doses of malathion are definitely associated with severe allergies and even death while small amounts are less defined with other health problems.
Malathion if ingested can be metabolized to malaoxon which is 61 times more toxic and a known carcinogen.
Poorly stored malathion has also been contaminated with isomalathion that has poisoned persons handling malathion.
The problem with widespread spraying is that organophosphates will kill many insects and accumulate in the food chain affecting fish, amphibians and birds. These natural predators play major role in controlling insects in the first place.
Mosquitoe populations also bounce back faster than their predators.
With indescriminating spraying we are actually making it easier for mosquitoes (both nuisance and disease carrying mosquitoes to become established. Not all mosquitoes will carry diseases and in fact most Manitoban ones don’ t. The introduction of new insects can always change things.
Winnipeg is fortunate that we do not have mosquitoes that carry tropical disease except for West nile viruses. One very serious concern is that if there were 3-4 weeks of warmer weather each summer other mosquitoes that carry tropical infections such as Aede egypyti could become established.
Invading or translocated species can become more established when an areas natural predators are suppressed. This has happened in many instances when the eradication of one problem insect led to mass environmental problems in each of the communites sprayed as detailed in Rachel Carson’s 1962 book , Silent Spring which launched the modern Environmental Movement .
Winnipegs can still do much to limit the spread of mosquitoes.
Eliminating sources of stagnant water both privately and in the community will decrease the breeding oppurtunities of mosquitoes. Ironically deeper bodies of water that can support frogs, koi fish and attract other insect predators of mosquitoes will have less mosquitoes since all the natural controls are in place. We can do our best to restablish this.
Horse owners can also immunize their horses against west nile virus since a horse being a large animal can be bitten by hundreds of mosquitoes daily and could amplify WNV in its vicinity. Immunizing horses prevents those mosquitoes from picking it up and spreading it to us.
Specific bacterial insectisides such as Bacillus thuringienis israelensisare (BTI) are lethal to mosquitoes but not other organisms.
Insecticides including malathion are still useful and people should make informed decisions on its use.. I encourage everyone to review available information before using any insecticide.