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Californians drive an average of 65% of their vehicle miles on state highways and county roads each day of the year, yet few are ever aware that toxic herbicides are discharged along the roads on which they travel. In fact, government agencies spray more than 130,000 gallons and 90,000 pounds of herbicides into the environment of these intensively used public facilities in a typical year.
Information regarding the amount and identity of the herbicides used along these roads was compiled for this report using data provided by more than seventy road maintenance agencies, including Caltrans headquarters, the twelve Caltrans district offices and fifty-eight county road maintenance departments. The assorted statistics depicting their herbicide use, shown on the charts on this page, are considered representative of a typical year since, according to a sampling of road maintenance personnel, the annual use of roadside vegetation control chemicals does not vary significantly. Figures representing Caltrans' annual use are drawn from MMS971-B forms for 1997 Pesticide Use Reports that are submitted directly to the Department of Pesticide Regulation. Those from each of the county road agencies are taken from 1996 and are based on Pesticide Use Report records submitted to each county's agricultural commissioner or from summaries compiled by agency staff. Eight of the herbicides account for 86.5% of the total used on California's thoroughfares. Surfactants, toxic chemicals which enhance the performance of herbicides, are also compiled as pesticidal agents according to the definitions and practices of the California Department of Pesticide Regulation.
Chemical Mixtures
Herbicide formulations are combinations of various chemicals. Several formulations can share the same active, or herbicidal, ingredient but, in addition, each usually contains any number and proportion of other chemicals. To present the most accurate account of the actual volume of chemical herbicides used on the state's roads, the total volume of all formulations containing the same active ingredients was combined and tallied for this report.
For example, the total of one active ingredient, glyphosate, is described as 62,512 gallons, referring to the combined total of glyphosate and any number and types of other chemicals mixed with it in the formulations used on California's roads. Herbicide use was described this way because chemical companies disclose only the identity of the active ingredient, refusing to identify most of the other chemicals contained in the formulations they brew. With the manufacturers' secrecy supported by federal and state pesticide regulators, the public is kept ignorant of the full extent of the chemicals actually being used.
Describing the relative volume of herbicide use is also excessively difficult. The industry imposed and government supported restrictions on information also prevents the public from conducting an adequate comparison of the value of weights and measurements.
Herbicide volumes are described in this report as liquid gallons and dry pounds, the composition of the chemicals before they are mixed with other materials such as water and detergents prior to application. A gallon may contain several times more chemical than does a pound but, again, the stealth of herbicide manufacturers prevents the public from obtaining enough information to compare the two forms. In all cases, the amounts described in this report are for concentrate before dilution.
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