California growers made 1,047 bifenthrin applications on cotton in 2023 — nearly double the 555 recorded in 2022 — and a new state law will force that chemical use into public view. Governor Gavin Newsom signed Assembly Bill 1603 on Sept. 27, requiring the Department of Pesticide Regulation to identify pesticides containing PFAS and track their use.

Bifenthrin, an insecticide listed in University of California integrated pest management guidance for cotton, is one of two cotton-relevant chemicals the Environmental Working Group classifies as a PFAS pesticide. The other is trifluralin, a herbicide that also appears in the university's cotton treatment resources. EWG co-sponsored the legislation.

The 2023 bifenthrin treatments covered a cumulative 107,087 acres, up from 69,098 acres in 2022, according to a California Department of Food and Agriculture report updated in April 2025. Each application to a field counts separately in that figure.

What does AB 1603 actually require?

The law does not ban anything. It establishes tracking and disclosure duties:

• The Department of Pesticide Regulation must flag PFAS-containing pesticides in its public pesticide-use database and report use trends.
• It must publish a list of registered pesticides with PFAS ingredients by Jan. 1, 2028.
• PFAS identification must appear in the database by Jan. 1, 2028, or when it posts 2026 pesticide-use data, whichever comes first.
• The scope covers PFAS intentionally added as active, adjuvant or inert ingredients.

An earlier draft went further: it would have blocked state registration of new PFAS-containing pesticides, except for applications submitted before Jan. 1, 2027. Lawmakers stripped that provision as the bill advanced.

Why does this matter for apparel sourcing?

For apparel companies, the law raises a question upstream of the water- and stain-resistant finishes usually associated with PFAS: which chemicals grow the raw fibre itself?

California already restricts regulated PFAS in new textile articles under AB 1817, whose prohibitions began taking effect last January, subject to exceptions. AB 1603 addresses a different supply-chain tier — agricultural inputs — through public reporting rather than product bans.

Once the database goes live, brands sourcing California cotton will be able to query PFAS pesticide use by chemical and acreage. That data will also be available to NGOs and journalists.

"Tracking and monitoring is the crucial first step. You can't fix what you can't see," Assembly member Nick Schultz, the Burbank Democrat who authored the bill, said in a statement.

How big is the PFAS exposure in state agriculture?

Across California agriculture, growers applied roughly 2.5 million pounds of PFAS pesticide active ingredients annually on average from 2018 through 2023, according to EWG, which calculated the figure from state pesticide-use records.

PFAS also account for a growing share of pesticide chemistry overall. A 2024 peer-reviewed paper in Environmental Health Perspectives classified 14 percent of U.S. conventional pesticide active ingredients as PFAS under the authors' definition. For ingredients approved during the preceding decade, the share reached 30 percent. The authors included researchers from the Center for Biological Diversity, EWG and Public Employees for Environmental Responsibility.

What drove the 2023 spike?

A wet winter set up a significant Lygus bug outbreak in California cotton fields in 2023, state agriculture data shows. Growers responded with more broad-spectrum insecticides, including bifenthrin.

Those treatments carry trade-offs. By killing beneficial insects, they can leave fields vulnerable to aphids and whiteflies later in the season. Those pests can cause "sticky cotton," which damages processing equipment and can make the fibre unsellable. The state report's authors called for chemical and nonchemical approaches to managing Lygus over the long term.

"We need to help our farmers transition away from these persistent chemicals so California can be a global leader in food safety," Susan Little, EWG's California legislative director, said in a Sept. 28 statement.

The sourcing decision ahead

Sourcing teams with California cotton in their fibre mix now face a disclosure deadline of their own. When the database publishes 2026 use data — no later than Jan. 1, 2028 — PFAS pesticide application records will be publicly searchable by crop. Brands that have scoped PFAS compliance only to finished-goods chemistry under AB 1817 will need to decide whether fibre-level chemical use belongs in their restricted substance and supplier questionnaires before that data becomes public.