What are the "Other" Ingredients in Lawn Care Products? Inerts & Adjuvants
Take a gander at the ingredients on an herbicide or pesticide label, and you'll note that "other" or "inert" ingredients significantly outweigh the active ones. For example, in the herbicide Barricade, ingredients are listed as follows:
Active ingredient: Prodiamine, 40.7%
Other ingredients, 59.3%
In the pesticide Roundup for Lawns, "inert" ingredients make up 93% of the product.
So, what's in there?
According to the Environmental Protection Agency (EPA),
An inert ingredient is any substance (or group of structurally similar substances if designated by the Agency), other than an “active” ingredient, which is intentionally included in a pesticide product. It is important to note, the term “inert” does not imply that the chemical is nontoxic (2015, 1).
Herbicide and pesticide formulations often include chemicals that help active ingredients work better. For example, they may help the active chemicals to penetrate or stick to leaves, or spread evenly over the leaf surface rather than beading (Witt). Inert ingredients may extend the product's shelf-life or protect active ingredients from degradation from sunlight. "Emulsifiers, solvents, carriers, aerosol propellants, fragrances, and dyes" are common (EPA 2020).
Chemicals added to lawn care formulations to improve their efficacy are often called adjuvants.
Inert Ingredients vs. Adjuvants
While reading about inert ingredients/adjuvants, I found what looked like conflicting information. While the EPA states that "all inert ingredients in pesticide products, including those in an inert mixture, must be approved for use by the EPA" (2015, 2), reputable university extension publications, like in the following quote from Penn State, note that "because adjuvants themselves have no pesticidal properties, they are not required to be registered by the U.S. Environmental Protection Agency (EPA)" (Hock). What's with the discrepancy?
Many sources, like the National Information Center (NPIC), define pesticide-enhancing chemicals as adjuvants whether they are found in a product formulation, or sold separately and mixed with a pesticide upon application (2019). However, the EPA calls a chemical an adjuvant only in the latter situation (2015, 7). In lawncare formulations, non-active ingredients are distinctly defined as "inert" ingredients by the EPA—even though they may serve the same function as adjuvants, and may even be the same chemicals.
This document offers information about registering pesticides with the EPA. It states:
Although adjuvants are not subject to registration when added in tank mix by growers, those adjuvants intended for use in conjunction with a pesticide in tank mixes for application to a food or feed crop/site are required to be cleared under the Federal Food, Drug and Cosmetic Act (FFDCA), prior to being used. Adjuvants that are to be used with pesticides [on crops or feed] are evaluated in a process similar to the one for inert ingredients" (1992, 1-3).
In sum: Inert ingredients included in a pesticide product must be registered with the EPA, but adjuvants mixed with a pesticide later by the chemical applicator do not need to be registered if they are not applied to food crops.
Why does this matter? Selling a chemical separately from a pesticide formulation, as an adjuvant, appears to be a way to get around registering a chemical with the EPA--which presumedly also circumvents safety testing.
So, do local lawn care applicators use unregulated adjuvants? Or do they typically use formulations whose inert ingredients are regulated? A casual internet search turned up several lawn care articles praising the use of adjuvants to enhance pesticide formulations. According to an article in Lawn & Landscape, an industry publication,
Pre-emergents and adjuvants have come a long way and it’s becoming much more common for lawn care operators to utilize them in their lawn care programs. In fact, the lawn care operators (LCOs) we spoke with all said that the use of these products is almost a “given” in most cases (Getz).
For folks who want to forage violets and dandelions or start a veggie garden in a previously treated lawn, it's important to consider that lawn applicators are allowed to apply chemicals that not only aren't permitted for food crops, but also may not be on the EPA's radar since they don't need to be registered. Most states don't regulate the distribution of adjuvants, either (Hock).
Which "Inert" Ingredients are in This Product?
It's pretty difficult to find out exactly which chemicals are lumped into the "Other" or "Inert" category on a pesticide or herbicide label. Companies are not required to disclose these ingredients, thus preserving trade secrets and recipes. The EPA has a confidential database of all inert ingredients and product formulas, but the public Trade Names of Inert Ingredients database is voluntary--not required--for chemical manufacturers and formulators to post information in (EPA 2015, 11).
If you visit the Trade Names of Inert Ingredients Database, you'll see the following column headers:
Since the database doesn't tell us what "910" and the other numbers indicate, I dug around and found an explanation of what these food-permitted safety ratings mean. The last page of this document offers a chart, if you're you're curious.
The EPA also offers this InertFinder database, which I found pretty unhelpful as a layperson. You can browse thousands of chemical names of inert ingredients, but you can't see which products the inert ingredients are found in. Nor can you search a product name to see what's in it, or learn much about the chemical's safety. If there is a specific inert ingredient whose name you somehow already know, you can find out whether it's approved for food use or for non-food use only.
To make sure I couldn't get my dirty gardener fingers on lawncare formulas, I reached out to Syngenta and Bayer (owner of Monsanto) to ask for a list of inactive ingredients in Barricade and Roundup, respectively, to share with gardening students and readers. Not surprisingly, I've received no reply after several months. I'll keep you posted if any formulas come my way.
Image: Homegrown calendula and mint leaves for tea
Fragrances in Pesticides
I'd never considered that pesticides and herbicides may have artificial fragrances added to make them smell fresh and appealing. This article discusses the safety risks to children when we make pesticides smell like bubble gum. It also asks how adults might use the products differently, perhaps exercising more caution and moderation if the products smell like toxic chemicals (which they are) rather than a bowl of cherries (Duffy).
I've often read that "Fragrance formulations are considered a 'trade secret' and therefore protected from disclosure – even to regulators or manufacturers" (Zanolli). Though this is true of fragrances found in hygiene and cleaning products (shampoos, soaps, detergents, perfumes, etc.), fragrances are regulated as inert ingredients when found in pesticides and a Confidential Statement of Formula must be submitted.
I couldn't find details about how much data a company must submit to make the case for the fragrance's safety. The EPA says that "the data needed to support the request for approval will depend on the use pattern of the fragrance. Requestors are encouraged to have a presubmission meeting with IIAB to determine the data necessary for a complete submission" (EPA 2015, 10).
Impurities
Impurities in pesticides are formed from chemical reactions that occur during pesticide formulation, or during storage. "These impurities generally exhibit similar physical and/or chemical characteristics to the active ingredient, but the toxicological or ecotoxicological hazards may differ...It is noteworthy that manufacturing processes cannot be optimized for control of all impurities, so they could vary [between] batches" (Azierta).
The EPA defines an inert ingredient as one "intentionally included" in a pesticide product. This means that impurities don't count. Impurities are also not considered to be "pesticide chemicals," which means they aren't required to have a tolerance or tolerance exemption like pesticides intended for food crops. "Therefore, there is no formal petition process for impurities in inert ingredient formulations" (EPA 2015, 7). However, the EPA adds:
All impurities in inert formulations need to be reported and are evaluated on a case by case basis. There is no [minimum] level for impurities related to inert ingredients. The Agency looks at the amount in the formulation, the manufacturing information, and what steps are taken to limit or remove impurities. This information would be needed to make a determination regarding the need for further action (EPA 2015, 7).
It's nice that the EPA requires companies to disclose which impurities are found in their products, but I don't get the sense that safety standards around impurities are very stringent.
Final Thoughts
When it comes to regulating the inert ingredients in a pesticide product, the EPA does some things right. As we've seen, lawn care chemical companies are required to submit safety information on active and "inert" ingredients, as well as fragrances. Impurities are also required to be reported.
If a new chemical is closely related to a permitted chemical, that's not enough to welcome it into the flock of the approved. It must be reviewed for safety just like any other new chemical (2015, 11). I'm also thankful that "regardless of their percentage in formulation...all intentionally added inert ingredients must be approved for the intended use" (12). This means that ingredients used in tiny amounts are not exempt from regulation.
However, as I explored in "Lawn Chemical Safety: Using Critical Thinking" and "Book Recommendation: Better Safe Than Sorry," EPA-approved doesn't indicate that a product is safe. Companies have long conducted and submitted their own safety research since the EPA hasn't had the budget to do its own "unbiased" testing on new chemicals.
In "Lawn Chemical Safety," I touch on the fact that studying chemicals in isolation is an inaccurate way to determine a chemical's safety. These substances are sold and applied in formulations, and they interact with other chemicals in the environment once applied. We've also learned that pesticides are often applied with adjuvants, which are not registered with the EPA and whose effects when mixed with pesticides have not been properly studied.
In Better Safe Than Sorry, Nora MacKendrick observes "a disturbing but familiar pattern in the U.S. retail landscape: a food or product is assumed to be safe, evidence emerges that associates it with health problems, this evidence is disputed, [by the corporations who produce them], and the product is left on the market, leaving consumers to figure out what to do" (2). When it comes to lawn care products, citizens can't begin to discern for themselves whether a formulation is safe when we don't have access to the ingredients list.
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Sources:
Duffy, Andrew. "Canada: Sweet-Scented Pesticide 'Sugarcoats a Toxic Pill'". Originally published by Ottowa Citizen. Aug 20, 2000. Viewed at CorpWatch: https://corpwatch.org/article/canada-sweet-scented-pesticide-sugarcoats-toxic-pill
Ace Hardware. "Roundup for Lawns Northern Weed Killer Concentrate." Visit the webpage here.
Azierta. "Toxicological evaluation of impurities in pesticides." Azierta Blog. Nov 12, 2019. https://www.azierta.com/en/blog/toxicology/toxicological-evaluation-of-impurities-in-pesticides
Getz, Lindsey. "Using Pre-Emergents & Adjuvants." Lawn & Landscape. Feb 13, 2013. www.lawnandlandscape.com/article/ll0213-pre-emergents-adjuvants-lawn-care/
Zanolli, Lauren. "Why smelling good could come with a cost to health." The Guardian. May 23, 2019. https://www.theguardian.com/us-news/2019/may/23/fragrance-perfume-personal-cleaning-products-health-issues
Hock, Winand. "Spray Adjuvants." Penn State Extension. Updated Feb 25, 2016. https://extension.psu.edu/spray-adjuvants
Lawncare Academy. "Increase Herbicide Effectiveness with Spray Adjuvants." viewed May 2, 2020. https://www.lawn-care-academy.com/spray-adjuvants.html
National Pesticide Information Center. "Adjuvants in Pesticides." Updated July 24, 2019. http://npic.orst.edu/ingred/adjuvant.html
New York State Department of Environmental Conservation. "Other Pesticide Product Registrations." https://www.dec.ny.gov/chemical/98907.html
United States Environmental Protection Agency. "General Information on Applying for Registration of Pesticides in the United States: Second Edition." Aug 1992. View here.
United States Environmental Protection Agency. "Inert Ingredient Frequently Asked Questions." Updated December 2015. www.epa.gov/sites/production/files/2015-12/documents/faqs.pdf
United States Environmental Protection Agency. "Inert Ingredients: Overview and Guidance." Updated January 30, 2020. https://www.epa.gov/pesticide-registration/inert-ingredients-overview-and-guidance
Witt, James. "Agricultural Spray Adjuvants." Oregon State University. http://psep.cce.cornell.edu/facts-slides-self/facts/gen-peapp-adjuvants.aspx
