Inerts

Is polyvinyl acetate allowed as a wood treatment? 

By Jacky Castañeda

The Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) defines an inert ingredient in a pesticidal product as “an ingredient which is not active.” USDA National Organic Program (NOP) regulations follow this definition when considering products formulated as pesticides. While the definition is simple and any number of ingredients may be defined by this classification, limitations exist, especially when dealing with synthetic substances.

Synthetic materials that fall under the inert classification must only serve an inert function. The National List at §205.601(m) allows synthetic materials “as classified by the Environmental Protection Agency (EPA), for use with nonsynthetic substances or synthetic substances listed in [§205.601—allowed synthetic materials] and used as an active pesticide ingredient in accordance with any limitations on the use of such substances.” In other words, synthetic inert materials in pesticides must fall under one of two designations:

1. EPA Lists 4A and B—Inerts of minimal concern, or
2. EPA List 3—Inerts of unknown toxicity, limited for use only in passive pheromone dispensers.

Therefore, a synthetic inert material must meet the definition of “inert” and appear in either the EPA’s 2004 List 4A or 4B (or List 3 if used in passive pheromone dispensers) for it to be allowed under the NOP regulations.

An example of such a synthetic material is polyvinyl acetate (PVA), found on List 4B. This material is a polymer resin commonly used as the chief component in wood treatment products. In this example, the active ingredient is PVA, as it functions as a sealant or protectant against mold, mildew and other such pests. Although the material is commonly used this way, in order for it to be compliant under the NOP regulations, the material must not be the active ingredient, but must instead be used as an inert ingredient with an allowed active ingredient; this definition does not apply to our example PVA product. However, if PVA were to be used as a binder to keep porous active ingredients together, the allowance would apply. This function is present in products with ingredients that cannot easily be mixed uniformly (e.g., oils, water and emulsifiers). PVA may be compliantly used to bind these ingredients together and form a uniform product.

OMRI requires that the function of each component be clearly stated for applying products. In order for a product to be allowed for organic crop production, all synthetic inert ingredients must be allowed under §205.601(m). Any product containing 2004 EPA List 4 synthetic inert ingredients must use those ingredients to formulate with allowed active components. Organic producers should always check with their certifier before using a new input product.   

This article was originally published in the summer 2021 edition of the OMRI Materials Review Newsletter.