Apply 50/50 mixture of Boric Acid and Diatomaceous Earth, to the dead air spaces under bathroom and kitchen sinks and to the spaces behind all your wall plug sockets and switch plates and under all appliances like the refrigerator, stove, and dish washer. This mixture can be applied using an old turkey baster. Just fill the baster and poof the powder in those places. Use sparingly as all you want to do is to coat those areas with a thin film of powder. This mixture is one of the least toxic of any of the pest control chemicals, however take precautions not to put it into places where your kids or pets might play.
NO pest control chemical is 100% safe. This mixture can also be used to control ant problems.
Diatomaceous Earth can be purchased at any swimming pool supply store for about $8.00/20lb bag.
Boric Acid can be purchased at most grocery stores for about $5.00/2 lb container. If you purchase these two items in their minimum sizes, you should be able to treat your whole house and every neighbors house on the block for five years. If kept dry, this coating will keep killing roaches forever!