Pesticides have become commonplace across most of the world, and the Bay Area is no exception. We use pesticides in and around our homes, on our pets, in our parks, on our crops, on our golf courses, and practically anywhere else weeds, insects, and other pests are unwelcome. While pesticides are designed to kill specific plants or insects, they often have harmful effects on nontarget species, including humans. Statistics on pesticide use in the Bay Area are only available for commercial applications -- even though past research has revealed that a significant share of pesticide use is in and around the home. Available data indicate that commercial pesticide application in the Bay Area has remained steady over the past 10 years. These overall statistics, however, obscure considerable increases and decreases in pesticide use in individual counties.
NRDC researchers examined pesticide data from the California Pesticide Use Reporting System that were compiled by the Pesticide Action Network North America, a nonprofit organization. The data cover all types of pesticides used by licensed applicators -- exterminators, golf-course greenskeepers, lawn services, farmers, commercial and park groundskeepers, etc. -- between 1991 and 1998, broken down by county. (Use of pesticides by individuals is not tracked.) NRDC researchers also examined these data for use of the most hazardous pesticides, including those that are acutely toxic, that can affect the reproductive system or child development, that are known carcinogens, or that attack the nervous system.
Overall, commercial pesticide use in the Bay Area has remained relatively steady since 1993, at around 11 million pounds applied per year. Some counties, however, had sharp changes in their usage patterns during the period examined. Total use in San Francisco, for instance, decreased more than 100-fold between 1991 and 1998, after a colossal increase in 1992. That year, the city used an astonishing 8.5 million pounds of pesticides, but in the following years brought its use down dramatically, to an average of less than 30,000 pounds per year from 1993 to 1998 -- by far the lowest amount of any Bay Area county.
In contrast, pesticide use in Santa Clara more than doubled from 1991 to 1998, and use in San Mateo went up by 81 percent. Other counties with increases included Sonoma (73 percent), Marin (62 percent), and Napa (30 percent). Which county applied the greatest quantity of pesticides? In 1998, the last year of tracking, that distinction went to Sonoma, which applied nearly 4 million pounds. Napa was next on the list at 2.7 million pounds; Solano and Santa Clara counties were third and fourth.
Total use of the most hazardous pesticides declined slightly during the same period, with decreases seen in all jurisdictions except Marin, San Mateo, Solano, and Sonoma. Use of acutely poisonous pesticides declined overall by 36 percent, with decreases seen in virtually all Bay Area counties. Use of carcinogenic pesticides rose between 1991 and 1998 by about 64 percent, largely as a result of significant increases in Marin, Napa, San Mateo, Santa Clara, Solano, and Sonoma Counties. Use of one particularly harmful group of pesticides, organophosphates (which are designed to attack insects' nervous systems by inhibiting production of the critical brain enzyme acetylcholinesterase -- and which have the same effect on humans), declined by 61 percent in the Bay Area. San Mateo County had a 31 percent increase in licensed use of these neurotoxins. Use of chemicals that interfere with reproduction or child development decreased by about 28 percent in the Bay Area overall, but increased in San Mateo, Solano, and Sonoma Counties.