Chapter 2
Registration of Biologicals How Product Formulations Affect Data Requirements Michael L. Mendelsohn, Thomas C. Ellwanger, Robert I. Rose, John L. Kough, and Phillip O. Hutton Office of Pesticide Programs, U.S. Environmental Protection Agency, 401 M Street S.W., Washington, DC 20460
Among those pesticide products currently registered with the U.S. Environmental Protection Agency (EPA), there exists a subgroup of products known as biologicals. Biologicals include 1) certain microorganisms and 2) compounds classified as biochemical pesticides that act to control pests as defined in § 2 of the Federal Insecticide, Fungicide and Rodenticide Act. Biochemical pesticides are distinguished from conventional chemical pesticides by their nontoxic mode of action toward target organisms and by their natural occurrence, e.g., insect pheromones. Data requirements for experimental use and full commercial registration of these pesticide products are somewhat different than those required for conventional chemical pesticide products. Formulation choice has a large impact on the data necessary to support a particular biological pesticide product. This chapter stresses the importance of formulation choice in product development as it relates to E P A regulatory requirements.
What Are Biological Pesticides? Pesticides are defined in § 2(u) of the Federal Insecticide, Fungicide and Rodenticide Act as "(1) any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest and (2) any substance or mixture of substances intended for use as a plant regulator, defoliant or desiccant" except those articles considered to be new animal drugs or animal feeds bearing or containing a new animal drug. Biological pesticides include microbial and biochemical pesticides. Microbial pesticides include the following microorganisms when they act as pesticides per FIFRA § 2(u): 1) eucaryotic microorganisms including protozoa, algae and fungi; 2) procaryotic microorganisms including bacteria and 3) viruses. This chapter not subject to U.S. copyright Published 1995 American Chemical Society
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Biochemical pesticides are distinguished from conventional chemical pesticides by their nontoxic or indirect mode of action toward target organisms and by their natural occurrence or structurally similarity and functional equivalence to naturally occurring compounds, e.g., insect pheromones and certain growth regulators.
EPA's Role The process through which a pesticide use is approved for large scale experimental or full commercial use is managed at the federal level by the Environmental Protection Agency. A major part of EPA's review process is the evaluation of data submitted by the applicant regarding mammalian and nontarget organism toxicology and product identity/analysis. In order to justify the approval of large scale experimental or full commercial use of a biological pesticide, the Agency must determine that such use will not result in unreasonable adverse effects to the environment. In other words, the pesticide cannot pose too high a risk to human health or the environment. Applicants can often affect the risk of their product by the way they formulate.
What Is Risk? Risk = (Hazard) X (Exposure) In order to affect risk in a product, one must either affect the hazard of the product or its exposure to man and/or the environment. Either end can be accomplished using various formulation strategies. When the way in which a product is formulated reduces the hazard and/or exposure to a particular pesticide product, often not only is risk reduced, but also the need for some of the nontarget organism and human health data normally required for large scale experimental and full commercial use may be obviated.
Nontarget Organism Data Nontarget organism Tier I testing requirements for biochemical and microbial pesticides generally include avian acute oral, avian dietary, freshwater fish L C , freshwater invertebrate L C , nontarget plant, nontarget insect and honeybee tests according to Title 40 of the Code of Federal Regulations (40 CFR) Parts 158.690 and 158.740. The test substance for these Tier I tests is normally the technical grade active ingredient (TGAI). However, both the actual nontarget organism studies required and the test substance of those studies can be affected by formulation. 40 C F R Part 158.75(b) provides that, on a case-by-case basis, testing may be required with the following: 5 0
5 0
1)
an intentionally added inert ingredient in a pesticide product;
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2)
a contaminant or impurity of an active or inert ingredient;
3)
a plant or animal metabolite or degradation product of an active or inert ingredient;
4)
the end-use pesticide product;
5)
the end-use product plus any recommended vehicles and adjuvants; and
6)
any additional substance which could act as a synergist to the product for which the registration is sought.
In addition to the TGAI, inert ingredients and manufacturing or formulation process changes have the potential to adversely affect nontarget organisms. Examples of these ingredients and their possible effects could include, but are not limited to, the following: 1.
Bacterial cultures have been stored under mineral oil to preserve them. Oils have been used in some formulations. Oils have been used as mosquito larvicides because they form surface films which also affect other nontarget organisms that depend on the integrity of the water surface.
2.
Plastic devices are used for controlled release of volatile pheromones that are classified biochemical pesticides. Depending on shape, they could result in intestinal damage to animals that eat them or trap animals that become entangled in them.
3.
A change in fermentation, recovery or manufacturing process may result in concentration of byproducts that, at low levels may cause no adverse effects, but as concentration increases, effects occur.
4.
A preservative, diluent or other formulation ingredient may be used that is potentially more toxic than the active ingredient.
5.
The biochemical or microbial pesticide is combined with a conventional chemical pesticide which exacerbates adverse effects.
6.
A granular, pellet or other formulation is introduced that is attractive to birds or other wildlife resulting in collection by animals and increased oral exposure compared to other formulations and uses of the same active ingredient.
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Product Specific Acute Toxicity Data Requirements The acute toxicity studies required for labeling purposes to support registration of pesticide products include: acute oral, dermal and inhalation toxicity, eye and dermal irritation, and dermal sensitization. This data is required to label these products for human safety, i.e., precautionary statements (how to avoid exposure) and statements of practical treatment (first aid if exposure does occur). This same data can trigger Restricted Use Classification and Child Resistant Packaging requirements depending on the resulting toxicity categories. Applicants may satisfy these requirements in any one of several ways. Applicants may elect to cite someone else's data providing the referenced studies used a test material similar, from an acute toxicological perspective, to the proposed end-use product. Applicants may elect to "bridge" their acute toxicity data to another data set by supplying a reduced set demonstrating the extent of similarity or difference compared to the existing data set. Applicants may also "bridge" their data by establishing that each of its active and inert ingredients are within a range of ingredient combinations between two registered products having complete data sets showing identical acute toxicity profiles. A third way of "bridging" data involves the quantity of water used in a formulation. A proposed simple water dilution of an existing registered product can utilize data from the registered product for those studies in Toxicity Categories III and IV (least toxic categories) since the product labeling can not reflect any less acute hazard. Studies would have to be submitted to fulfill requirements not covered by Toxicity Category III and IV studies. Alternatively, a proposed product containing less water than a registered product may utilize data from any studies already in Toxicity Category I (most toxic category) since the product labeling can not reflect any higher level of hazard. Again, studies would have to be submitted to fulfill the remaining requirements. Beyond citing existing studies on similar products or "bridging" using a combination of existing data and new data, registrants may elect to generate all their own data or have a contract laboratory generate it. For microbial/biochemical pesticide products, the components/constituents of the formulation, including both active and inert ingredients, can have a great influence on the acute toxicity data requirements. It must be understood that the term "inert ingredient" applies only to the fact that the ingredient is pesticidally inert, and does not mean that the ingredient is assumed to be biologically inert. It has been the Office of Pesticide Programs' experience that it is frequently the inert ingredients rather than the active ingredients which drive the acute toxicity profile for a product. This is the case for conventional chemical pesticides and especially for biologicals where the active ingredients are more frequently relatively innocuous. Each of the six acute toxicity data requirements for labeling must be satisfied by citing existing studies, submitting new studies or using a combination of cited and submitted studies. Still another option is a request for one or more specific waiver(s) accompanied by a detailed scientific justification. Waivers are addressed in two documents, 40 CFR Part 158.45 and a recently completed Acute Toxicity Waiver Guidance Document. The latter is available by phone at (703) 308-8341. Biological end-use products whose inerts are naturally occurring materials such as water, cereals,
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vegetable oils, sugars, corn cobs, etc. or are formulated in such a way as to substantially reduce human exposure are more likely to be granted requested waivers than products using inerts such as petroleum distillates, alcohols or surfactants. The former are less likely to pose any significant health risks. It should be noted that the dermal sensitization study required for both chemical and biochemical end-use pesticides is not required for microbial end-use pesticides. Instead, the registrant must submit any reported incidents of hypersensitivity which occur.
Examples of Formulation Based Reductions in Mammalian Toxici ty Data Requirements As stated earlier, certain risk scenarios can be mitigated by altering the exposure to the hazardous substance since risk is the product of hazard times exposure. Potential hazards from biological pesticides, like other pesticides, can often be addressed by lowering the exposure through pesticide formulation technology. The efficacy for many pheromone biochemical pesticides is dependent on being able to deliver the volatile compound at certain rates over an extended period of time to confuse mating behavior. Therefore, the efficacy can be enhanced by dispensing formulations that slow the rate of delivery. These range from cigarette filters, hollow tubes and twist ties to flakes, chopped fibers and microscopic granules. Taking advantage of this development period in pheromone technology, the EPA is encouraging pheromone pesticide manufacturers to develop their pheromone products with dispensers that reduce the risk of food contact or incorporation by being large enough to be easily seen and retrievable. On December 8, 1993, the Agency proposed exempting arthropod pheromones from the requirement of a tolerance when used in solid matrix dispensers at a rate not to exceed 150 grams active ingredient/ acre /year in accordance with good agricultural practices (58 FR 64539). Further, the Agency established an exemption from the requirement of a tolerance for all inert ingredients of certain types of semiochemical dispensers under 40 C F R Part 180.1122 on December 8, 1993 (58 FR 64494). With use of these dispensers the manufacturers avoid having to address the risks associated with repeated, direct food exposure. By reducing pesticide exposure, pheromone applicants have often successfully obviated the need for teratology and subchronic feeding studies on their product due to the formulation and use rate chosen. Microbial pesticides have also been formulated into products that may alter the toxicological risks through reduced exposure. Some fungal pathogens of insects are known to produce toxins of unknown mammalian toxicity. Broadcast spray formulations of such a fungal agent would require the manufacturer to directly test the product for the presence of these toxins considering the extensive exposure to the fungal agent especially in raw food. Use of these same agents in enclosed traps greatly reduces the likely exposure to any toxin potentially produced by the fungus. The lessened exposure can mitigate against the need to test the product directly for toxins, especially if previous acute toxicology testing showed no untoward effects.
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Product Performance Product formulation can affect performance in a variety of ways. Microbial pesticides are uniquely formulated in comparison to their traditional chemical counterparts for a variety of reasons. Most bacteria and viruses are activated in the gut of the host, and thus must be eaten to be effective. Obviously any changes in the product formulation which would stimulate ingestion may also improve product performance. Likewise, the active ingredients of a product may be quite capable of providing control, but will never have the opportunity if the formulation inhibits ingestion. Arthropod organoleptics; studying the gustatory stimulation and inhibition of various formulations, has become a critical element in the production of microbial pesticides intended for insect control. A second area of formulation technology affecting performance involves protection of the microbial active ingredient from degradation. For viruses and bacteria, this most commonly involves protection from the ultraviolet spectrum which can shorten the active life of the product on the leaf surface. The addition of U . V . inhibitors to viral pesticides is now becoming a commonplace practice to increase the duration of effectiveness. One area where formulation technologies are similar between microbial and traditional chemical pest control agents are the elements of sprayability, spreadability, and stickability. For any product to be successful, it must be able to be applied with the equipment typically available by growers. This is no mean feat considering the coarse raw intermediate product that comes out of the fermentor. If a product doesn't stay in suspension, it may never make it out of the nozzle. No microbial agent can control pests from the inside of a 500 gallon tank. Once out of the nozzle (hopefully undamaged), the microbial formulation must be able to provide the required coverage with reasonable volumes of diluent. Even coverage is essential, for uneven coverage may result in uneven control. Finally, the formulation must have staying power, to stick to the plant. After delivery, the microbial will be subjected to rain, wind and other factors. Again, even the best product cannot perform its' intended function if the product has been washed to the soil while the pests are still up chewing on the plant. Acknowledgment The authors thank William Schneider for kindly presenting this chapter at the 1994 American Chemical Society National Meeting.
References Betz, F . , Forsyth, S., and Stewart, W. "Registration Requirements and Safety Considerations for Microbial Pest Control Agents in North America" In L . Marshall, L . Lacey, and E . Davidson, ed. Safety of Microbial Insecticides (CRC Press, Boco Raton, F L , 1990).
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Mendelsohn, M . , Rispin, A . , and Hutton, P. "Environmental Protection Agency Oversight of Microbial Pesticides" In A . Rosenfield and R. Mann, ed. Dispersal of Living Organisms into Aquatic Ecosystems (Maryland Sea Grant College, College Park, M D , 1992). Matten, S., Schneider, W . , Slutsky, B . , and Milewski, E. "Biological Pesticides and the U.S. Environmental Protection Agency In L . K i m , ed. Advanced Engineered Pesticides (Dekker, N Y . 1993.) U.S. Congress, Federal Insecticide, Fungicide, and Rodenticide Act of 1972, 7 U . S . C . 136 et seg^, as amended October 24, 1988. U.S. Congress, Federal Food, Drug, and Cosmetic Act, and as amended. 21 U . S . C . 201 et. seq.. 1991. Title 40, Code of Federal Regulations, Parts 158, 172, and 180, 1991. Mendelsohn, M . , Delfosse, E . , Grable, C , Kough, J., Bays, D . , and Hutton, P. "Commercialization, Facilitation and Implementation of Biological Control Agents: A Government Perspective" in C. Wilson and M . Wisniewski ed. Biological Control of Postharvest Diseases - Theory and Practice (CRC Press, Boco Raton, F L , 1994.) RECEIVED
January 31,1995
