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Section Five: The Government's Response

Dealing with New Information

For nearly two decades, new discoveries about pesticide threats have prompted a number of responses: chief among them, more extensive pesticide monitoring.

In Florida, for example, the 1982 discoveries of aldicarb in groundwater led to a one-year ban on use of the product, while regulators considered how to control the threat. After the year's prohibition, the state limited allowable application rates of the insecticide for use on potatoes and citrus, restricted the time-periods for application to avoid heavy rains, and prohibited use of the product within setback areas surrounding drinking water wells. The setback distance varied depending upon local conditions, ranging from 300 to 1,000 feet. ²

The same pesticide was found above recommended health protection levels in Wisconsin's Central Sands potato-growing region. The 1981 discovery of the problem there led to state-imposed restrictions on application rates, requirements that the pesticide be used only by "certified applicators," and new limitations on the retreatment of fields on which aldicarb had been applied in the previous year. ¹

In 1984 the State legislature passed the Wisconsin Ground Water Law, and some concepts from that law are mirrored in EPA's proposals to address pesticide contamination. ² Under the Wisconsin law, the state sets two types of standards or criteria to trigger action. "Enforcement standards" are set at the level of public health concern -- corresponding in general to federally set drinking water standards or state alternatives. Detection of a pesticide above this level triggers a prohibition against use in the affected area. The additional tier of standards are termed "Preventive Action Limits" or PALs. 

Three tiers of PALs are used in Wisconsin: 10 percent of the enforcement standard, 20 percent and 50 percent. Detection of a pesticide at these levels triggers increasingly stringent restrictions to "prevent" further contamination and avoid the situation in which the groundwater will exceed the enforcement standard. ³

California's Central Valley was particularly hard hit in terms of pesticide contamination of groundwater, and that diverse state with its large agricultural sector may now be unique in the extent of its groundwater monitoring and reporting requirements as well as its pesticide record-keeping rules. 4

Following passage of the California Pesticide Prevention Act in 1985, the state developed its own list of suspected problem pesticides and has focused many of its efforts on this list. If a pesticide is determined to have contaminated groundwater as a result of legal application, the chemical is subject to a review which could potentially result in cancellation of its uses in the state. ⁵

As a matter of practice, the State has shied away from cancellations, instead relying on various application safeguards and geographic restrictions. In the cases of atrazine and simazine -- weed-killers used in both agricultural and non-agricultural settings -- the state did prohibit non-crop related uses. ⁶ Neither atrazine nor simazine may be used in California for control of vegetation on rights-of-way. Both are still used on crops -- though usage in California is not as intense as it is in the Midwest and other field crop-growing regions of the country.

At the federal level, EPA undertook the National Pesticides in Drinking Water Supply Survey, an extensive and unprecedented water sampling effort aimed at assessing the nationwide extent of the problem and developing a better understanding of groundwater vulnerability. That multi-year and multi-state study, though criticized by some environmentalists as focused on the wrong targets, indicated that 10.4 percent of community wells and 4.2 percent of private water supply wells had detectable levels of pesticides. From the survey results, EPA estimated that less than 1 percent of community or private rural wells contain pesticides at levels above established health-based standards.7

The most frequently detected pesticide-related contaminants were DCPA acid metabolites, breakdown products of DCPA -- a weed killer used on lawns, turf, golf courses and a number of fruits and vegetables -- and atrazine, the broad-spectrum weedkiller used on field crops as well as lawns and rights-of-way. ²

In addition, EPA staff worked to gather and summarize existing health effects data on many pesticides. Few drinking water standards for pesticides had been set prior to the Survey, and EPA knew that testing for many chemicals "unregulated" by the Safe Drinking Water Act would raise questions about possible health threats. Thus, the Agency worked to set non-binding health advisory levels for pesticides not governed by enforceable drinking water standards. ⁹ At the same time, the Agency also moved forward with enforceable drinking water rules or MCLs (maximum contaminant levels) for more pesticides. (See table below.)

Under authorities of  FIFRA, the Agency also issued "data call-ins" requiring new laboratory and field data from pesticide makers in order to support continued registration of the chemicals. Sixteen pesticides were targeted for information-gathering in 1985. 

For one suspected "leacher," alachlor, EPA compelled its maker to undertake an extensive national study. Monsanto's study, interestingly, found less than 1 percent of sampled wells with detectable levels of alachlor but 12 percent with detectable levels of atrazine. The atrazine findings were well above those in the National Pesticide Survey, and the difference in detections underlines the importance of understanding selected test methods. The "detection limit" for atrazine in the Monsanto study was more sensitive than that used in EPA's Survey. Thus, the two studies -- though they appear at odds at first glance -- may, in fact, be consistent. ²

EPA also began to seek out and collect monitoring reports from around the country, assembling them into a single pesticide database and following up on these miscellaneous reports to see if the source of the contamination could be determined -- non-point or regular field application of pesticides versus point sources such as spills, mixing and loading zones, pesticide manufacturing or illegal use. This effort helped to lay to rest the last stubborn vestiges of the long-held belief that normal agricultural practices posed no threat to groundwater resources.

1.  Holden, Patrick W., Pesticides and Groundwater Quality:  Issues and Problems in Four States, 1986.

2.  Gustafson, David I., Pesticides in Drinking Water, 1993.

3.  See, for example, "Wisconsin Groundwater Standards:  An Explanation of Chapter 160, Wisc. Stats." at <http://www.dnr.state.wi.us/org/water/dwg/gw/gwchp160.htm>.

4.  For more on pesticide use reporting, see the California Environmental Protection Agency's "Pesticide Use Reporting:  An Overview of California's Unique Full Reporting System" at <http://www.cdpr.ca.gov/docs/dprdocs/userptng/purhtm.htm>, the Northwest Coalition for Alternatives to Pesticides' (NCAP) information on the Oregon Pesticide Education Network (OPEN) and that coalition's goals for pesticide use reporting reform in Oregon at <http://www.pesticide.org/PUR.html>, and information of New York's pesticide reporting law in the Department of Environmental Conservation's Annual Report on New York State 1997 Pesticide Sales and Applications, 1998 available at <http://www.dec.state.ny.us/website/dshm/prl/>.  Also see the recommendations for changes to New York's reporting law made by Environmental Advocates and New York Public Interest Research Group in Plagued by Pesticides: An Analysis of New York State's 1997 Pesticide Use and Sales Data, 1998 at <http://www.envadvocates.org/public_html/Pest/recommendations.html>.

5.  See Pease, William S., "Pesticide Contamination of Groundwater in California," 1995 at <http://www.ucop.edu/cprc/grwater.html>.

6.  In addition to above article, see summary of remarks by Paul H. Goslin, Assistant Director for Enforcement, Environmental Monitoring and data Management Division, California Department of Pesticide Regulation, in Proceedings of the August 1996 National Workshop:  Pesticides and Ground Water State/Tribal Management Plans, 1997.

7.  US EPA, "National Pesticide Survey," 1991 at <http://pmep.ccc.cornell.edu/facts-slides-self/facts/gen-pubre-water-survey.html>.

8.  See, for example, cautions about DRASTIC vulnerability ratings in North Dakota Department of Health, " North Dakota Geographic Targeting System for Groundwater Monitoring, 1996 at  <http://www.health.state.nd.us/ndhd/environ/wq/gwt/gwt.htm>.  For a discussion of the importance of the scale of the assessment, read about a comparison of county-level versus state-level vulnerability predictions in Smith, P.A., et al, "Influence of Geographic Database  Scale on Prediction of Groundwater Vulnerability to Pesticides" in Journal of Soil Contamination, 3(3), 1994.

9.  EPA Health Advisories (HA's) provide information on contaminants that can cause human health effects and are known or anticipated to occur in drinking water. These are non-enforceable guidance numbers based on non-cancer health effects for different durations of exposure (e.g., one-day, ten-day, longer-term, and lifetime). Information on all the health advisories available can be accessed at <http://www.epa.gov/OST/Tools/dwstds-s.html> or by calling EPA's Safe Drinking Water Hotline at  1-800-426-4791 Monday thru Friday, 9:00 AM to 5:30 PM EST.

10. US EPA, Office of Ground Water and Drinking Water, "Current Drinking Water Standards" available at <http://www.epa.gov/safewater/mcl.html>.

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