California’s Rodenticide Ban, Measured: Pest Control Switched Poisons Instead of Baiting Less

A law with a measurable before and after

AB 1788, the California Ecosystems Protection Act of 2020, was signed on 29 September 2020. It prohibits the use of four second-generation anticoagulant rodenticides, brodifacoum, bromadiolone, difenacoum and difethialone, anywhere in the state until the Department of Pesticide Regulation completes a reevaluation and certifies new restrictions. It exempts public health and vector control agencies, water infrastructure, offshore island eradication, declared public health emergencies, research, medical waste generators, certain registered facilities, and “agricultural activities”, which the law defines to include food warehouses, slaughterhouses, canneries, factories, breweries and wineries. A later statute describes the restriction as implemented in January 2021.

California’s pesticide use reports record every structural rodenticide application by active ingredient, before and after. We extracted every year from 2016 to 2023, the most recent published, to see what the law changed.

What happened to the restricted compounds

Source: California Department of Pesticide Regulation, Pesticide Use Reports 2016 to 2023, site code 10, Structural Pest Control, application counts by active ingredient. Difenacoum, the fourth restricted compound, had at most 13 applications in any year. Author calculation.

What it means. The restriction worked on its own terms, quickly. Structural applications of the four compounds fell 85.4 percent between 2020 and 2021 and 87.6 percent by 2023. Before the law they made up nine in every ten rodenticide applications in California structural pest control; by 2023, fewer than one in eleven.

What limits it. 263,926 applications remained in 2023. The reports record the site code but not which exemption applied, so we cannot say how much of the remaining use is in food facilities, public health work or something else. Difethialone held up best, at 24 percent of its 2020 level in 2023.

What took their place

Source: as above. All rodenticides are the eleven active ingredients in the published CSV. Author calculation.

What it means. Pest control did not bait less. Rodenticide applications rose in every year from 2016 to 2023, and their share of all structural applications rose from 11.9 to 16.2 percent. The restriction changed which poison went into the bait station. Diphacinone, an older first-generation anticoagulant, absorbed the largest share, rising from 127,104 applications in 2020 to 1.2 million in 2023 and becoming the fifth most applied ingredient in all of California structural pest control. Bromethalin, a neurotoxin that is not an anticoagulant, rose eighteenfold.

What limits it. An application count says nothing about the quantity of bait or the number of rodents. Cholecalciferol peaked in 2021 and fell back, so the substitution was not a single clean switch. Cholecalciferol use had already doubled in 2020, the year the bill passed, which suggests some businesses moved before the law took effect.

The substitute was restricted next

AB 1322, the California Ecosystems Protection Act of 2023, was signed on 13 October 2023. It extends a statewide prohibition, with the same kinds of exemptions, to diphacinone, and designates it a restricted material, until the department completes a reevaluation of it.

What it means. The 2023 law targets the compound that the 2020 law made dominant. Diphacinone’s 1,203,949 structural applications in 2023 are the baseline the second restriction acts on. The 2024 Pesticide Use Report, not yet published at the time of writing, will show whether the pattern repeats and where the applications go next. On these data, the candidates are bromethalin, cholecalciferol and chlorophacinone, a first-generation anticoagulant that AB 1322 does not name and whose applications rose from 15,384 in 2021 to 228,057 in 2023.

What limits it. We report what the statutes say and what the use data show. We do not assess whether the substitutes are safer for wildlife; our report on rodenticides in California wildlife found anticoagulant residues in 128 of 158 animals tested in 2022, with second-generation compounds still among those most often detected in birds, and our report on rodenticides not measured in water covers the gap in water monitoring.

Weight tells the same story

Second-generation anticoagulants applied in structural pest control fell from 62.8 pounds of active ingredient in 2020 to 3.8 pounds in 2023, while diphacinone rose from 5.3 to 55.0 pounds. Rodenticide baits contain very low concentrations of active ingredient, so these weights are small; their direction matches the application counts.

Tests of the finding

1. Is the break at the law, or a trend?

Method. Compared year-on-year change in second-generation applications before and after 2021.

Result. From 2016 to 2020 they rose every year, by between 0.3 and 19.8 percent a year. In 2021 they fell 85.4 percent. No earlier year comes close.

Limitations. Other things changed in 2021, including the pandemic’s effect on commercial buildings; they cannot explain a fall confined to four named compounds while rodenticide use overall rose.

2. Did total rodent work fall?

Result. No. Rodenticide applications rose from 2,475,381 in 2020 to 2,708,435 in 2021 and 3,042,550 in 2023.

3. Complete series

Method. All eight annual archives from 2016 to 2023 were read in full, 58 county files each, with the application count counted per active ingredient.

Result. No missing years. Totals for 2022 match the product-level total used in our other reports exactly, 3,017,398 rodenticide applications.

Related: where the remaining restricted-rodenticide use happens, and how concentrated it is, in after California’s rodenticide ban, county by county.

Related research: who applies rodenticides in California, by sector; wildlife exposure before and after the restriction.

Download the data

The tables in this report are published as CSV files under a Creative Commons Attribution 4.0 licence. You may republish, remix and build on them, including commercially, with attribution to The Pest Control Brief and a link to this page.

• Structural rodenticide applications, pounds and reports by active ingredient and class, California, 2016 to 2023 (CSV, 88 rows)

How to cite this report

The Pest Control Brief, “California's Rodenticide Ban, Measured: Pest Control Switched Poisons Instead of Baiting Less”, 2 October 2026. https://thepestcontrolbrief.com/california-rodenticide-ban-data/

References

1. California Legislature. AB 1788, Pesticides: use of second generation anticoagulant rodenticides (California Ecosystems Protection Act of 2020), Chapter 250, Statutes of 2020. leginfo.legislature.ca.gov AB 1788. Accessed 2 October 2026.
2. California Legislature. AB 1322, Pesticides: second-generation anticoagulant rodenticide: diphacinone (California Ecosystems Protection Act of 2023), Chapter 836, Statutes of 2023. leginfo.legislature.ca.gov AB 1322. Accessed 2 October 2026. Source of the statement that AB 1788 was implemented in January 2021.
3. California Department of Pesticide Regulation. Pesticide Use Report annual archives, 2016 to 2023. files.cdpr.ca.gov/pub/outgoing/pur_archives/. Accessed 2 October 2026.
4. The Pest Control Brief. Rodenticides in California wildlife. thepestcontrolbrief.com/rodenticide-wildlife-exposure-data. Source of the 2022 wildlife testing figures, from the California Department of Fish and Wildlife.

How the series was built

Scope. Every Pesticide Use Report record with site code 10, Structural Pest Control, for 2016 to 2023.

Unit. The application count field, summed by active ingredient. Rodenticide products contain one active ingredient each, so ingredient totals add up to product totals.

Classes. Second-generation anticoagulants are the four the statute names. First-generation anticoagulants are diphacinone, chlorophacinone and warfarin. Non-anticoagulants are bromethalin, cholecalciferol, strychnine and zinc phosphide.

What we did not do. We did not attempt to identify which exemption covered remaining second-generation use, did not analyse agricultural or other site codes, and did not assess wildlife outcomes.

Limitations. Structural pest control only; rodenticide use under agricultural and other site codes is excluded. About 12 percent of licences state no application count on some reports. Data end in 2023.

Last reviewed: 2 October 2026.

For reporters covering rodenticide policy

Most quotable statistics

1. Structural applications of second-generation anticoagulant rodenticides in California fell 85 percent in the first year of the state’s restriction, from 2,128,528 in 2020 to 310,290 in 2021.
2. Total rodenticide applications rose 22.9 percent from 2020 to 2023, to 3,042,550.
3. Diphacinone applications rose 9.5 times, from 127,104 to 1,203,949, before California restricted it too in 2023.
4. Bromethalin applications rose 18 times, from 48,433 to 870,661.
5. Second-generation compounds fell from 90 percent of rodenticide applications before the law to 8.7 percent in 2023.

Caveats that travel with them

Structural pest control only. Exempt uses continue, and the reports do not record which exemption applied. Application counts are not quantities of bait or numbers of rodents.

Press summary

California’s 2021 restriction on second-generation anticoagulant rodenticides cut their use in structural pest control by 85 percent in its first year, but pest control did not use less rodenticide overall, according to an analysis of state pesticide use reports by The Pest Control Brief. Applications of the restricted compounds fell from 2.13 million in 2020 to 310,000 in 2021, while total rodenticide applications rose 22.9 percent between 2020 and 2023. Diphacinone, an older anticoagulant, rose ninefold to 1.2 million applications and was itself restricted by a 2023 law. Bromethalin, a non-anticoagulant neurotoxin, rose eighteenfold.

Headlines editors could use

1. California’s rodenticide ban worked, and pest control switched poisons
2. Second-generation rodenticide use fell 85 percent in a year
3. The replacement rodenticide California banned next
4. Rodent baiting rose 23 percent after California’s poison restriction

Questions about the restriction

Did California’s rodenticide ban reduce use?

Of the four restricted compounds, yes. Their structural pest control applications fell from 2,128,528 in 2020 to 310,290 in 2021 and 263,926 in 2023.

What rodenticides are banned in California?

AB 1788 prohibits brodifacoum, bromadiolone, difenacoum and difethialone statewide with exemptions, from 2021. AB 1322, signed in October 2023, adds diphacinone. Both remain in force until the state completes reevaluations.

Why are banned rodenticides still being used?

The law exempts uses including public health and vector control, water infrastructure, food warehouses, food production sites, factories, breweries and wineries. The reports do not say which exemption applied.

What did pest control companies use instead?

Mainly diphacinone, a first-generation anticoagulant, and bromethalin, a non-anticoagulant, with cholecalciferol and later chlorophacinone.

Did rodent control decline after the ban?

No. Rodenticide applications in structural pest control rose from 2.48 million in 2020 to 3.04 million in 2023.

Is diphacinone banned in California?

AB 1322, signed 13 October 2023, prohibits its use statewide with exemptions and makes it a restricted material until a reevaluation is completed. Our data end in 2023, before that restriction applied.

Are the replacement rodenticides safer for wildlife?

This analysis does not assess that. It measures what was used.

Where can I get the yearly figures?

All eleven rodenticides, eight years, with applications, pounds and report counts, are in the CSV above.