The primary pesticides used in the larval control operations have very low human/mammalian toxicity and most are very environmentally friendly. Most are biological agents that have bacteria as the active ingredient and are very specific to mosquitoes while in the larval stage. Minnows are often used when feasible as a natural control.
The pesticides used to control adult mosquitoes also have very low human/mammalian toxicity and have been used and tested for many years. Most are "synthetic pyrethroids" which are man-made to work like a natural product made from exotic chrysanthemum plants. Some are also natural pyrethrums and are actually made from plants. This is where some people may have an allergic reaction if they are allergic to these types of plants. These people may contact their local mosquito control district and ask to be placed on a "contact list" to be contacted when spray operations are planned, or call the spraying hotline to find out when spraying is scheduled and where.
Even though these same pesticides are used in the agricultural market for pest control on plants, they are applied in the public health industry at a much lower application rate and are widely used in home pest control products. These products have very limited residual and biodegrade rapidly in the environment. They have very low human/mammalian toxicity. A good part of the odor and taste that might be experienced is from the mineral oil that is used as a diluent. There is currently much research and work being done with aqueous materials that can eliminate or at least greatly reduce the use of these oils.