Cockroaches do not cause disease, and they rarely cause household damage. They can cause human allergies, particularly among asthma sufferers. However, they are hated by people as a symbol of uncleanliness.
Substances toxic to humans should not be used to kill cockroaches indoors. Homes are tightly sealed, especially in winter, and the inside environment is not subject to natural environmental processes. Pesticides remain dangerous for much longer periods indoors than if they were applied outdoors. People living in houses treated with insecticide can experience severe health reactions to the chemical. Cockroaches are so common that they have the potential to reach any building at any time. Spraying can not solve the problem. Prevention of cockroach infestations is your best means of ensuring a cockroach free environment.
To control cockroaches in buildings:
Don't expect instant results. Any place infested with cockroaches will also be infested with their eggs, so it takes at least a couple of weeks to get rid of all of them. That's another reason why the pesticides often used to kill them are so dangerous - they have to remain lethal for several weeks too.
See also Environment Canada's fact sheets on pest control.
Provided by the Health Dangers of Urban Use of Pesticides Working Group of the Region of Ottawa-Carleton, Ontario Canada. Approved by Regional government and by the Ottawa-Carleton Health Department. Please feel free to copy.