Environmental Health Officers take questions and queries from our clients practically every day on a wide range of subjects, Mosquito Control included. One of the questions that reached the desk of the Coalition is timely for its relevance to the most recent string of posts (Part 11, Part 1) on Malathion usage in our region.
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QUESTION: Fogging, the carrier is diesel. Has there been any study about what breathing that in will do to the body?
ANSWER:
Pesticides have always been a source of concern for trained and licensed operators, the scientific community and, of course, the general public whom we shall refer to as “residential/bystanders”. Our fears have centered on the simple fact that since such products are designed to kill, albeit pests and vermin, they can also be harmful to the human population as well. However, a review of the scientific literature would substantiate what we already know in the Vector Control Unit, that exposure by inhalation to chemicals used for fogging has little or no significant adverse health effects on residential bystanders, whether be they adults or children.
The Pest Management Regulatory Agency (PMRC) of Health Canada, referring to Malathion, explains it thus: “The droplets of pesticide are very small and do not drift or deposit like larger droplets. Spray droplets may evaporate during this period of suspension in the air, and so, not deposit at all…. Thus, exposure is minimized and adverse effects are, as a result, limited.” The ATSDR (Agency for Toxic Substances and Disease Registry put it this way, again speaking of Malathion: “(it) can be absorbed after inhalation, oral, or dermal exposure, but is readily excreted in the urine, and does not accumulate in organs or tissues.” The National Library of Medicine and the National Institutes of Healthpublished a study on the subject of fogging using organophosphate insecticides.
The study indicates that “…inhalation of spray mist was negligible. No clinical signs or symptoms of intoxication were discovered in either study, nor were inhibitions of cholinesterase (ChE) activity of health significance established under the conditions of the studies.”
The Vector Control Unit of the British Virgin Islands’ Environmental Health Division has in the past fogged to control adult mosquitoes using chemical products from the Organophosphate (Malathion) and Synthetic Pyrethroid (Chemrez 25 S, Biomist) classes in addition to Diesel Oil, which serves as an accelerant. The Diesel burns the chemicals to produce a white smoke that the wind can easily carry in and around our premises where the pest mosquitoes are most active. Understandably, residential bystanders tend to feel vulnerable when overcome by that “smoke.”
The Cholinesterase enzyme is inhibited by chemical exposure and thus is a good pointer to the ill effects of a pesticide on the human person. The Vector Control inspectors employed by the Environmental Health Division were all tested for lowered Cholinesterase inhibition in 2005. All of them were passed fit. Some of the inspectors have worked in this field for many years, decades in some instances.
However, exposure to the ULV (ultra low volume) formulations employed by truck-mounted equipment is to be avoided during and immediately after a spray event in the same way that a house should be evacuated after spraying for mosquitoes with a household aerosol.
