Pesticide product ingredients are classified as active or inert. Active ingredients are the chemicals that are meant to kill or repel the pest, while inert ingredients (inerts) perform some other function for the pesticide product. Thousands of chemicals are used as inerts, and they are not required to be listed on product labels, though many are neither chemically nor toxicologically “inert.”
Inert ingredients are often biologically active, yet labeled as inerts under lax regulatory requirements protecting “confidential business information.” Some inerts are known to cause cancer and others have been linked to genetic damage, reproductive harm and a wide variety of health problems.
In general, the purpose of each inert ingredient is to increase the pesticide’s ability to realize the toxicologic end points, such as developmental neurotoxicity, genotoxicity, and hormone function disruption in pests.
According to the National Pesticide Information Center, inert ingredients are generally added to pesticide products for the following reasons:
- To stabilize the product and extend shelf-life
- To help the pesticide stick to surfaces like leaves and soil
- To help the pesticide spread over surfaces
- To help the pesticide dissolve in water
- To prevent caking or foaming
- Ease of application (prevent clogging, product uniformity)
- To make ingredients compatible
- Drift control
Inerts can also increase the pesticides’ toxicity to non-target pests, including increased phytotoxicity and toxicity to fish, amphibians, and microorganisms. Inerts may also increase human exposure by increasing dermal absorption, decreasing the efficacy of protective clothing, and increasing environmental mobility and persistence.
Resources:
Unidentified Inert Ingredients in Pesticides: Implications for Human and Environmental Health (Environmental Health Perspectives)
NPIC: Inert or “Other” Ingredients