Effects of B.t. preparation additives
Commercial B.t. preparations basically contain the toxin crystals, spores and cellular debris to which various substances are added, the majority of which are the water or oils used to suspend the spores and toxins. Next, additives intended to increase the insecticide's effectiveness are added to the suspension. These additives are diluents (water, oil, powdered clay), emulsifiers, thickeners, humectants, foam inhibitors, substances that encourage the insects to eat the crystals (such as sugar), and stabilizing agents (antioxidants, antibacterials, evaporation suppressants). It must be specified that since the nature and chemical composition of these additives are protected trade secrets, it is impossible to know the exact potential toxicity of commercial B.t. preparations.
However, we do have enough information to state that some of these additives have slightly irritating properties, as confirmed by the warnings contained on commercial product data sheets. The organs most sensitive to additives are the respiratory system and the eyes. Eye irritations and conjunctival congestion observed in rabbits are caused by the abrasive properties of the additives. A case of corneal ulceration, diagnosed in a man who splashed insecticide into his eye, was also caused by the additives. Finally, the higher frequency of eye, nose and throat irritation, chapped lips and dry skin in workers exposed to B.t.K., as compared to a control group, could be a response to the presence of products other than the bacteria. In addition, the symptoms of irritation were observed more in workers with a prior history of allergies (asthma, eczema, seasonal allergies).
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