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Report Table of Contents
Executive Summary
Roads are the main arteries of life and commerce for most Americans. In California, close to 80,000 miles of state highways and county roads are used each day by millions of people who commute, transport materials or keep these roads open and safe. Each day of the year, 65% of the miles traveled by Californians are driven on state and county thoroughfares. Yet unknown to the communities through which they pass and the people who labor and travel on them, these roads are regularly sprayed with toxic herbicides.
 California's Department of Transportation (Caltrans), a nearly $6 billion bureaucracy, discharges these dangerous chemicals onto state highways yet cannot provide even the most fundamental information regarding the size and extent of its herbicide spray program.
In The Poisoning of Public Thoroughfares: How Herbicides Blight California's Roads, Californians for Alternatives to Toxics (CATs) describes for the first time ever how state and county agencies douse California roads - especially in the most populous regions - with huge quantities of chemical herbicides. Research for this report was conducted throughout a two year period beginning in early 1997 when a groundswell of public outrage over roadside spraying on the North Coast forced Caltrans to stop drenching local highways with toxic chemicals.
Caltrans and county transportation agencies suppress the seasonal profusion of roadside weeds for safety and for appearance. Caltrans claims that its goals of increased driver visibility and reduced risk of fire demand the use of chemical herbicides, but communities on the North Coast showed no increase in automobile accidents or roadside fires during a four year hiatus from herbicide spraying.
In limited toxicological studies, chemicals used in roadside vegetation control have been shown to be harmful to humans, wildlife and the environment. Of the eight most popular herbicides used on California roads, one is confirmed under California law (Proposition 65) to be a proven human carcinogen and development toxicant, six are identified by the federal Environmental Protection Agency as possible human carcinogens and three are linked to birth defects. More than half have been found in ground water and three quarters may pollute the air. The effects of these roadside poisons have not been sufficiently documented. Caltrans has refused to pursue further investigation of a controversial 1987 study that found elevated cancers among its employees or of a 1994 Department of Pesticide Regulation study that showed significant levels of herbicide residue on its applicator's clothing.
Several safe, effective and affordable ways to end the use of health threatening chemical herbicides exist. Caltrans and county road agencies can immediately reduce the amount of toxic chemicals they release by not spraying in areas managed solely for appearance. There are proven nontoxic alternatives to highly dangerous chemicals such as mowing, planting competitive vegetation, and mulching. Caltrans is also experimenting with steam spraying and corn gluten, but these efforts are constrained by the minimal financial commitment the agency is willing to make.
Based on the findings of CATs' research, it is recommended that Caltrans and county road agencies immediately budget sufficient funds to implement recognized alternatives methods of vegetation control and explore new options. During the transition to nontoxic roadside maintenance, Caltrans and county agencies should notify affected populations of herbicide spraying and cease the use of toxic substances on roadsides where they are not needed for safety.
California's use of roadside herbicides is widespread
CATs' report discloses that Caltrans and county road agencies apply more than 132,000 gallons of herbicide in liquid formulation and 91,000 pounds of dry weed killers to roadsides in a typical year. The more populated the area, the heavier the dose - despite danger to public health. Much of the spraying activity is condensed into a few weeks in late winter and early spring.
CATs found that Caltrans applies an average of about five gallons of liquid and more than two pounds of dry herbicide formulation per road-mile of the 15,000 miles of highways under its jurisdiction. In addition, the report found that 51 of the state's 58 county governments also rely on chemical poisons to kill weeds, averaging more than one pound and one gallon of herbicide per mile along the 64,000 miles of roads under county management.
Based on the combined herbicide applications of Caltrans and county road agencies, CATs found that people in Los Angeles, Orange, and Contra Costa counties were exposed to the greatest concentration of chemical weed killers. In stark contrast, no toxic spraying was conducted either by Caltrans or local road agencies in the counties of Mendocino, Humboldt and Trinity, which are located in the most vegetated region of the state.
Roadside herbicides are harmful to people and the environment
The eight herbicides shown in the chart account for 86.5% of roadside spraying in California. Studies of these toxic substances are limited, but the trials which have been conducted indicate that they possess a great potential for causing human illness and environmental degradation. None have proven non harmful to humans or animals.
Of the eight herbicides listed in this chart, the U.S. EPA recognizes six as possible human carcinogens and four may cause birth defects. Seven, including glyphosate, are linked to toxicity in the liver and blood. Another, oxadiazon, is recognized by state and federal agencies as a liver and kidney toxicant which also causes birth defects and cancer. Seven exhibit varying degrees of toxicity to fish while four are harmful to birds. Four of the toxic chemicals on this list have been detected in groundwater by California's Department of Pesticide Regulation, and the University of Florida has determined that six possess a high potential for runoff.
Roadside spraying constitutes a serious threat to the health of those traveling or working on California's roads. At increased risk are children, people with compromised immune systems, and the 17% of Californians found in a survey conducted by the Department of Health Services to have symptoms of chemical sensitivity. Also, women and men whose careers keep them on the road may be subject to greater risk through frequent exposure. These unsuspecting thousands are not notified when toxic chemicals in the form of herbicides are released into their work environment.
Caltrans is not effectively curbing herbicide use
Caltrans serves as a model for much smaller county road agencies throughout the state, yet has failed to act as a responsible state agency. As CATs discovered, most of Caltrans' twelve district offices could not provide a basic summary of their use of toxic herbicides. Caltrans officials in Sacramento are not even sure how much the agency spends on herbicides - annual expenditures can only be estimated at $4 to $6 million for weed killing chemicals.
A pledge made in 1992 to reduce its use of herbicides by 50% by the year 2000 is unlikely to be met by Caltrans despite millions of dollars spent on research studies. Promises to stop applying herbicides solely for the sake of appearances have been ignored, and the agency has not actively pursued the identification of school bus stops although it pledged to avoid spraying these areas.
Alternatives can replace toxic herbicides
Despite agency reluctance to halt the use of herbicides, several effective, affordable and nontoxic alternatives exist to kill weeds when it is deemed necessary. Most important is attention to what is actually required for adequate weed management. The use of chemical weed killers can be eliminated where they are used merely to satisfy a particular aesthetic, possibly reducing the overall use of these poisons to a significant degree.
A viable alternative to toxic herbicide spray is Integrated Vegetation Management (IVM), a systemized approach to weed control in which different methods are integrated into a total vegetation management system. In its 1992 Environmental Impact Report, Caltrans pledged to adopt an IVM program, but even at this late date has conducted extremely limited trials.
Caltrans and county road agencies could also use devices that spray nontoxic dry steam to kill weeds and their seeds. Steam spraying machines proved highly successful for British Columbia railways and have been developed by a California company for use on roadsides. Corn gluten, which stops weeds from sprouting, was intensively studied by Iowa State University before registration as an herbicide in California in 1998. Both alternatives are currently being explored in isolated, underfunded studies by Caltrans and the University of California, as is the use of fire-resistant native plants to choke out unwanted weeds.
There's even a venerable piece of equipment that has been in use since before chemical herbicides were invented: the mower. Counties that have not used herbicides for years manage their roadsides with special mowers, and further research into equipment design could improve their utility.
Recommendations
Based on its investigation, CATs urges Caltrans and county road agencies to immediately make the following changes for the health and well being of all those who work or travel on California's roads:
Invest at least as much as the agencies now spend on chemicals - up to $6 million annually for Caltrans - to implement alternative means of vegetation control and contract with IVM experts to recognize and eliminate unnecessary spraying.
During the transmission from chemical to nonchemical means of vegetation control, provide accurate advance notification, on-site warnings and records detailing herbicide use and audit already existing records to fully assess the actual cost of using herbicides to provide a basis for comparison to alternatives.
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