PANNA: Use of the Most Toxic Pesticides Increasing in California


Pesticide Action Network Updates Service (PANUPS)

Use of the Most Toxic Pesticides Increasing in California

July 16, 1999

Use of pesticides that are nerve poisons, reproductive toxins or cause cancer continues to increase in California, according to an analysis of pesticide use data recently released by the California Department of Pesticide Regulation (DPR). In addition to their analysis, the state has also released use data for each year from 1991 to 1997 that includes both agricultural and non-agricultural pesticide applications; pesticides used by consumers are not included.

The director of DPR called for use of high hazard pesticides to be reduced in California, signaling a new approach to pesticide regulation in the state, according to Californians for Pesticide Reform (CPR). Under the previous governor’s administration, pesticide use data were not released to the public for three years and no analysis of trends in use of the most toxic pesticides was ever conducted. CPR, a coalition of groups fighting for elimination of the most hazardous pesticides, is calling on state government to put greater efforts into pesticide use reduction and promotion of sustainable alternatives.

Carcinogenic Pesticides

According to the DPR data, use of pesticides that cause cancer increased steadily by about four million pounds a year–from over 31 million pounds in 1991 to over 56 million pounds in 1997, a total increase of 81%. Pesticides included are those listed by the U.S. Environmental Protection Agency as B2 carcinogens (probable human carcinogens) or are on California’s Proposition 65 list of chemicals “known to cause cancer.” Among the highest use pesticides listed by DPR in this category were petroleum oils and mineral oil. The inclusion of these compounds is misleading, since only a small fraction of the components of these oils are carcinogenic, compared to a substance such as metam sodium, which is 100% carcinogenic. If oils are excluded from the category, the total pounds of carcinogenic pesticides drops by half, but the rate of increase climbs to 111%.

Excluding the oils, the highest use carcinogens were metam sodium and 1,3-dichloropropene (also known as Telone), both soil fumigants. Metam sodium use increased from 4.8 million pounds in 1991 to nearly 15 million pounds in 1997. Use of Telone was severely restricted in the early 1990s, with only 14,000 pounds used in 1991 and 2,200 pounds in 1993. After the restrictions were removed, however, use skyrocketed to 2.4 million pounds in 1997, an amount 17 times greater than the 1991 use figure.

Reproductive Toxicants

Use of pesticides that cause birth defects, reduced fertility and sterility and are identified by the State of California as reproductive hazards increased 34%, from 24.4 million pounds in 1991 to 32.6 million pounds in 1997. This is an average of two million pounds per year, including a slight reduction since 1995. While methyl bromide remains a major pesticide in this category, its use has decreased slightly from 18 million pounds in 1991 to 16 million pounds in 1997. Metam sodium, in addition to being a carcinogen, is also a reproductive toxicant and was a major contributor to increased releases of this class of chemicals into the environment.

Organophosphate and Carbamate Pesticides

Use of acutely toxic systemic nerve poisons (organophosphates and carbamates) increased 17%, from 13.8 million pounds in 1991 to 16.1 million pounds in 1997–an average of 500,000 pounds per year. These pesticides disrupt enzymes that control the nervous system. Increased used of chlorpyrifos and methomyl (widely used on cotton) and thiobencarb (used mainly on rice) accounted for much of the change.

PAN North America and CPR will be releasing an in-depth analysis of California pesticide use trends following the projected August release of the 1998 pesticide use data. The upcoming report will evaluate pesticide use, agricultural production and pesticide toxicology.

With the release of these data, DPR grouped pesticides by their toxicity categories for the first time. These groupings were very similar to the Pesticide Action Network North America’s approach in its 1997 report, “Rising Toxic Tide: Pesticide Use in California 1991-1995.” The DPR analysis provided pesticide use data for carcinogens, reproductive toxicants, organophosphate and carbamate pesticides (grouped together because they have a similar mechanism of toxicity to the nervous system), and pesticides that are listed as Toxic Air Contaminants or as Groundwater Contaminants, in both pounds of active ingredient and acres treated.

Pesticide Use Report, Annual 1997, DPR’s summaries of pesticide use in 1997 categorized by chemical and crop or site, is available on DPR’s web site at

Source/contact: Pesticide Action Network North America.



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