Acute Injection Toxicity/Pathogenicity for the assesment of MPCA products (Microbial Pest Control Agents). EPA-OPPTS 885. 3200: 1996.

Test wih the Certificate of Good Laboratory Practices (GLPs).

The results obtained with lung toxicity/pathogenicity studies following this standard, provide information on the health hazards that can arise after a single exposure intravenously (for small microorganisms such as bacteria) or intraperitoneal (for microorganisms such as fungi or protozoa). of an MPCA (Microbial Pest Control Agent) product intended for pest control, using a single high dose in a test with experimental animals, and monitoring post-exposure. If the test substance cannot be administered in a single dose, it should be divided into small doses over 24 hours.

The MPCA product can contain any type of infectious agent (bacteria, fungi, parasites or viruses). The MPCA agent evaluated must be quantified by the appropriate microbiological methods according to the type of agent, so the manufacturer must report the microbial content of the product and its quantification per unit volume or weight of the product since the method requires administering a dose of 107 MPCA units to each animal.

The recommended animals are rodents (mice or rats) young adults of both sexes, of similar weight, although with justification other types of animals can be used. The inoculated animals should be evaluated with a daily follow-up from the beginning of the inoculation until a later period of 21 days (unless it must be prolonged because the signs of toxicity and pathogenicity persist, or the animals die). The clinical follow-up to observe the corporal and behavioral manifestations of the animals must be complemented with the pathological examination of a part of the inoculated animals (6 animals) three days after the administration of the product, and weekly thereafter, after administration (4 evaluations on days 3, 7, 14 and 21, with study of internal organs of 6 animals in each of them). In addition, an uninoculated control group undergoing the same type of monitoring should be included. If the toxicity of the vehicle (excipient) of the MPCA product is not known, another control group for the toxicity of the vehicle (excipient) of the product should be included, so the manufacturer/promoter of the test should inform about it. Periodic and final monitoring, in addition to observations to detect clinical manifestations, will include weighing animals, gross examination of internal organs, and detection/quantification of the MPCA agent in the lungs, liver, brain, kidneys, spleen, lymph nodes, blood and cecal content. The qualitative and quantitative microbiological evaluation aims to assess the organic spread and clearance, if any, of the MPCA agent. The intermediate slaughter of animals will only be carried out in the case of intravenous inoculation. 

Manufacturer/Promoter Required Information

For the reasons stated, the manufacturer/promoter of the MPCA test must inform the type of presentation of the MPCA product; the size of the particles in case of being solid or of being suspended in a liquid; of the microorganism included in the product and in the case of fungi if it contains conidia (spores) or also hyphae of the mycelium; of its quantification per unit of weight or volume; and of the knowledge, if it exists, of the toxicity of the vehicle (excipient). With the information provided, the laboratory will be able to evaluate the total number of animals needed to carry out the study, as well as the microbiological methods necessary for its evaluation. In addition to the untreated control group required, the EPA guideline includes two additional control groups: a vehicle control group (only required when the toxicity of the vehicle is unknown) and a control group dosed with inactivated MPCA (needed when the final product is tested to evaluate the toxic properties of the MPCA). Depending on the product to be tested, the study should be performed with the indicated controls. Twenty additional animals would be used for each one of the chosen controls.