- Cabana, Jean
Gouvernement du Québec
In 1984, within its fifteenth operation of the aerial spraying of insecticides against the spruce budworm (Choristoneura fumiferana), the Ministère de l'Energie et des Ressources (Department of Energy and Resources) carried out sampling program to evaluate the concentrations of Bacillus thuringiensis in the air of two municipalities of region 01 (St-Honoré de Témiscouata and Causapscal). A total of 49 24-hour air samples were taken from June 11 to July 7. Analysis of the samples showed concentrations varying from 0 to 132.59 spores-min/1 (94. spores/m^3). However, they were generally less than 2 spores-min/1 (1.4 spores/m^3). A definite correlation was noticed between the concentrations detected and spraying operations performed close to these stations but other factors, such as the wind, the amount of product sprayed and the local topography, might have had a significant effect on the drift of B.t. spores.
B.t. toxicity tests performed on man and certain animal species tend to reveal that it is harmless when inhaled or ingested even in doses several thousand times greater than those detected during this study. Thus, it appears that spraying biological insecticides would constitute a negligible hazard to the health of the citizens of these municipalities.