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Mammalian safety of microbial agents for vector control: a WHO memorandum
Abstract:
This Memorandum outlines recommended safety tests for application to biological agents under consideration for widespread use for pest control. The basic principles utilized in developing these recommendations were that: (i) the hazards presented by microbial pesticides are inherently different from those associated with chemical pesticides and the tests used to determine hazard potential to man should reflect this; (ii) a high proportion of negative results is likely; (iii) tiered testing systems should be used; negative data obtained at any level would obviate the need for further testing; (iv) the primary tier testing protocols should be designed to expose test animals to the microbial agents under conditions that provide maximum opportunity for the expression of any adverse effects.Outlines of tests proposed for use with four groups of biological agents (bacteria, fungi, protozoa, and viruses) are given. The safety tests required at each level of development of a microbial agent are described.The present status of safety testing of the agents already under development for possible use in vector control is considered. It is concluded that, for Bacillus thuringiensis H-14 and B. sphaericus, a level of safety testing has been reached that permits their use in large-scale field trials.Suggestions for applied research are made, covering safety aspects of cottage-industry production of microbial agents, studies on allergic responses, serological surveys on laboratory workers, and the investigation of environmental persistence of newly developed agents.
Insights
This study recommends tiered safety testing for microbial pesticides, emphasizing distinct protocols for biological agents compared to chemical pesticides. Bacillus thuringiensis H-14 and B. sphaericus are deemed safe for field trials.
Area of Science:
- Environmental Science
- Microbiology
- Toxicology
Background:
- Microbial pesticides present unique hazards distinct from chemical pesticides.
- Existing safety testing paradigms may not adequately address biological agents.
- A structured approach is needed to evaluate the safety of microbial pest control agents.
Purpose of the Study:
- To outline recommended safety testing protocols for microbial agents used in pest control.
- To establish tiered testing systems that prioritize early identification of potential hazards.
- To assess the current safety testing status of microbial agents for vector control.
Main Methods:
- Development of tiered testing strategies tailored to microbial agents (bacteria, fungi, protozoa, viruses).
- Emphasis on protocols maximizing the potential for adverse effect expression in test animals.
- Review of safety data for agents like Bacillus thuringiensis H-14 and Bacillus sphaericus.
Main Results:
- Recommended tiered safety testing protocols for various microbial agent groups.
- Identification of Bacillus thuringiensis H-14 and Bacillus sphaericus as meeting safety standards for large-scale field trials.
- Assessment of current safety testing levels for microbial agents in vector control.
Conclusions:
- The proposed tiered testing system ensures comprehensive safety evaluation of microbial pesticides.
- Bacillus thuringiensis H-14 and Bacillus sphaericus demonstrate sufficient safety for advanced field testing.
- Further research is suggested for cottage-industry production safety, allergic responses, and environmental persistence.