Acute Inhalation Toxicity Testing of Bacterial-Based Microbial Pesticide Products
Microbial pesticides based on bacteria are increasingly used because they offer more environmentally friendly pest control. These products have advantages such as high specificity toward their target and rapid degradation in the environment. However, because they utilize living organisms, their safety aspects need to be evaluated more thoroughly.
One important aspect of safety assessment is acute inhalation toxicity, which refers to the potential hazards that arise when the product is inhaled over a short period. Acute inhalation toxicity testing for microbial pesticides is necessary to ensure that no toxic effects, irritation, or infections occur in the user’s respiratory system.
The importance of this test continues to grow alongside the expanding use of microbial pesticides. The biological characteristics of bacteria, which differ from chemical substances, require a more specific approach in inhalation toxicity assessment. With proper testing, the product can be confirmed to be safe for use while also supporting the sustainable application of microbial pesticides.
- Bacterial Pest Control Agents: Who Are They?
- Acute Inhalation Toxicity Testing of Bacterial-Based Microbial Pesticide Products
Bacterial Pest Control Agents: Who Are They?
Within the group of microbial pesticides, bacteria are among the most widely used and extensively studied agents for controlling plant pests. Bacteria are utilized because they can produce various toxic metabolites, antibiotics, enzymes, or volatile compounds capable of suppressing the growth of plant pathogens and insect pests. Some commonly used bacterial groups include Bacillus, Streptomyces, Pasteuria, and Pseudomonas.
Species of Bacillus are the most dominant bacterial agents used in biological control. The most well-known example is Bacillus thuringiensis (Bt), which produces Cry proteins with insecticidal activity specific to various insect groups. Bt is used to control larvae of Lepidoptera, Coleoptera, and Diptera through a mode of action involving damage to the insect midgut epithelium after ingestion.
Streptomyces is known for producing a wide range of antimicrobial metabolites and enzymes that are effective against plant pathogens. These bacteria act through space and nutrient competition, antibiotic production, and rhizosphere colonization. Several strains are used to control soil-borne diseases such as Fusarium and Rhizoctonia.
Bacteria of the genus Pasteuria are used as bionematicides. These microbes specifically infect plant-parasitic nematodes by attaching to their cuticle, then developing inside the host and eventually killing it. Due to their high specificity, Pasteuria species are considered safe for non-target organisms.
Pseudomonas fluorescens and Pseudomonas chlororaphis are frequently used as biocontrol agents to suppress plant diseases. These bacteria produce siderophores, antibiotics, and enzymes that inhibit pathogens, and they are also capable of inducing systemic resistance in plants.
Acute Inhalation Toxicity Testing of Bacterial-Based Microbial Pesticide Products
Acute inhalation toxicity testing is an important parameter used to assess the potential hazards of a substance when inhaled over a short period. For bacterial-based microbial pesticides, this parameter is particularly relevant because spores, whole cells, or bacterial fragments may become airborne during application. Such conditions increase the likelihood of direct exposure to the respiratory system of users or field workers.
Bacterial pesticides may form aerosols or fine dust when applied as sprays, dry granules, or dispersed powders. Bacteria in such formulations can enter the respiratory tract if particle sizes are below 50 micrometers, allowing them to reach the lower regions of the lungs. Owing to this risk, international regulations mandate inhalation toxicity evaluation to ensure that exposure does not result in toxic effects or infection.
Acute inhalation toxicity tests typically follow OECD Guidelines 403 or 436, involving several hours of exposure in test animals, followed by a 14-day observation period. For bacterial pesticides, the goal is not only to detect toxic symptoms but also to determine whether the bacteria can survive, multiply, or cause inflammation in lung tissue. This approach is necessary because some biocontrol bacteria produce metabolites or enzymes capable of triggering immune responses.
Despite advancements, no in vitro method currently exists that can fully replace animal inhalation testing for microbial pesticides. Cell culture models such as the air–liquid interface (ALI) system offer progress but remain limited because they cannot simulate bacterial infectivity or the complex interactions between living microbes and respiratory tissues. As a result, animal testing remains the gold standard for assessing inhalation toxicity.
Read more:
3 Recommended Pesticide Lab Tests to Pass the Ministry of Agriculture’s Distribution Permit!
After understanding the potential inhalation risks of bacterial microbial pesticides, it becomes clear that safety testing is not merely a regulatory formality, but a fundamental step in ensuring products are truly safe for users. Manufacturers need to ensure every formulation has undergone accurate, well-documented pesticide testing that aligns with international standards so it can be trusted by the market and meet registration requirements. This is where the role of a qualified testing laboratory becomes essential.
IML Testing and Research provides comprehensive pesticide testing services to evaluate product safety and quality, including toxicity testing in accordance with international guidelines. With standardized laboratory facilities and accurate, reliable test results, IML helps ensure your pesticide products are ready for safe and responsible use. Consult your pesticide testing needs with IML Testing and Research to ensure every product on the market complies with required safety standards.
Author: Dherika
Editor: Sabilla Reza
References:
Betz., F.S., Hammond, B.G., & Fuchs, R.L. (2000). Safety and Advantages of Bacillus thuringiensis-Protected Plants to Control Insect Pests. Regul Toxicol Pharmacol, 32(2), 73-156.
Wend, K., Zorrilla, L., Freimoser, F.M., & Gallet, A. (2024). Microbial Pesticides – Challenges and Future Perspectives for Testing and Safety Assessment with Respect to Human Health. Environmental health, 23, 49, 1-29. https://doi.org/10.1186/s12940-024-01090-2.
