California Pesticide Use Data and Endangered Species - ACS

Chapter 7

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California Pesticide Use Data and Endangered Species Larry R. Wilhoit* Department of Pesticide Regulation, 1001 I Street, Sacramento, CA 95812 *E-mail: [email protected]

Most biological opinions related to pesticides and endangered species assume worst-case scenarios for pesticide use, largely due to a lack of reliable pesticide use data. California maintains a large database of pesticide use data with 38 years of detailed and accurate data on each production agricultural pesticide application and summary information on other, mostly non-agricultural applications. These data can be used to develop more realistic assessments of the effects of pesticides on endangered species.

Introduction Section 7 of the Endangered Species Act requires all federal agencies to consult with the U.S. Fish and Wildlife Service or the National Marine Fisheries Service when any action the agency plans to take may affect a listed endangered or threatened species or their designated habitat. If the initial consultation indicates that the proposed action is likely to adversely affect a listed species, the appropriate Service will prepare a biological opinion to determine if the action will jeopardize the continued existence of a listed species. Several biological opinions have been developed by the U.S. Environmental Protection Agency (EPA) to evaluate the potential effect of pesticide registrations on listed species. In these biological opinions, several assumptions were made about pesticide use: pesticides are applied at maximum label rates, all agricultural areas are treated, and treatments can occur at any time of the year. These assumptions are generally © 2012 American Chemical Society In Pesticide Regulation and the Endangered Species Act; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.


quite unrealistic but are made because most states do not have adequate data on actual pesticide use. In the absence of data, these worst-case scenarios are made to ensure adequate protection of endangered species. However, California has detailed and accurate pesticide use data, which can be used to make more realistic assessments (1). With these data one can determine which pesticides were applied, their actual rates, the specific geographical areas where the pesticides were used, the dates the pesticides were used, and the methods of applications. Also, data exist for more than 20 years for all agricultural pesticide use and 38 years for federal and California restricted use pesticides.

Description of the California Pesticide Use Reporting System The California Department of Pesticide Regulation’s (DPR) Pesticide Use Report (PUR) is probably the largest and most complete database on pesticide use in the world. The system to collect data on pesticide use in California started in the 1950s, although only data since 1974 are stored in DPR’s database. Also, before 1990, only use data of restricted use pesticides was collected. Starting in 1990, all pesticide applications in production agriculture and all applications made by businesses that sell or apply pesticides were required to be reported. In 1990, DPR expanded pesticide use reporting primarily to assess more accurately dietary risks from pesticide exposure. However the data are now used for a wide variety of environmental and public health purposes, including refining risk assessments, promoting farm worker health and safety, analyzing human exposure patterns, protecting threatened and endangered species, monitoring and investigating environmental issues, and improving pest management. State and federal agencies, universities, farmer organizations, the pesticide industry, and public interest groups use the PUR extensively. The data collected on production agricultural pesticide use differ somewhat from data collected on other kinds of applications. Production agricultural use data include applications of pesticide products to growing crops, agricultural fields, most forest trees, and ornamental turf. For brevity, these uses will be referred to as “agricultural uses.” The other kinds of use include post-harvest commodity treatments and non-agricultural uses by commercial applicators, such as applications to rights of way, landscapes, and structures. These heterogeneous applications will be referred to as “non-agricultural use.” The agricultural data collected includes the pesticide product’s name and EPA registration number, the amount of pesticide applied, the method of application, the crop treated, the application date, a grower identification code, a code for the field treated, the area of the field treated and planted, and the field location within a square-mile section. Less information is collected for non-agricultural use: rather than the specific geographical location and day of application, only the county where the application was made and the month of application are reported. The total amount of pesticide applied is still reported. After the data are entered into DPR’s database, a procedure is run to determine the active ingredients in each 94 In Pesticide Regulation and the Endangered Species Act; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.


reported pesticide product and the pounds of each active ingredient applied. This information is provided by another DPR database containing the properties of all pesticide products registered in California. Data collection starts when pesticide users fill out a form to report each pesticide application. Most of these forms are paper, but web-based reporting is becoming more prevalent. These reports are sent to the appropriate county agricultural commissioner’s (CAC) office where the data are stored in a county database. Data are periodically sent to the state headquarters at DPR. Each day a DPR program loads all new data from the counties and checks the data for errors. Errors are sent back to the originating county, where staff members are requested to correct them. By April, DPR should have received nearly all the county data from the previous year. However, the error corrections may take a few more months. The final versions of the PUR annual reports are typically available in December and contain the prior year’s data.

Data Quality Because of the importance of the PUR for many groups and individuals, it is critical that the database be as accurate and complete as possible. Any complex database with over 45 million records and 30 data fields, as is the case with the PUR, will almost certainly contain errors. Errors are especially likely to appear in the PUR because of the nature of the data, the diversity of people submitting the data, and the diversity of people entering the data. PUR data are complex and many of the people who submit data may not have an incentive to take the time to insure their accuracy. There are many possible explanations for errors. For example, there are many pesticide products with similar names and registration numbers and product-specific label information is often incorrectly recorded. It is easy to report the wrong units of weight or volume for an application since reporting forms offer several choices of units and type size is undeniably small. When only part of a field is treated, it may not be clear how many acres to report as treated. The crop actually planted may differ from that originally anticipated when growers get a permit to apply restricted use pesticides, and growers may not inform the CAC about this change. The PUR is extensively checked for errors both at the CAC office and at DPR headquarters, so despite all the potential problems, the data are quite accurate. When the data are checked at DPR, about 2% of records are found to have some kind of error. Most of these detected errors are corrected before the final versions of PUR annual reports are available. However, not all errors can be identified and so the true error rate is unknown. Also, even a 0.1% error rate in amount applied, if the magnitude of an error is large, could seriously affect an analysis. For example, an error was discovered in a record of an application of a product containing the active ingredient orthosulfuron in 2010 that would have changed the statewide total pounds of orthosulfuron applied from 665 to 5,700. 95 In Pesticide Regulation and the Endangered Species Act; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.


Uses of the PUR Pesticides can have detrimental effects on wildlife species, affecting health and reproduction and in some cases causing mortality. Data available from the PUR, such as the pesticide product, use rate, timing, and geographical location of applications, can be useful information for identifying and regulating pesticides potentially harmful to species of concern. DPR works with the CACs to merge PUR data with geographic information on locations of endangered species habitats provided by the California Department of Fish and Game, the U.S. Fish and Wildlife Service, and the National Marine Fisheries Service. The resulting database helps CACs resolve potential conflicts when pesticide applications occur in or near endangered species habitats. DPR and the CACs can also examine patterns of pesticide use near habitats to determine the potential effects of prospective measures aimed at protecting vulnerable species. This location- and pesticide-specific information can be accessed using DPR’s Endangered Species Custom Realtime Internet Bulletin Engine (PRESCRIBE) (URL http://www.cdpr.ca.gov/docs/endspec/prescint.htm). Studies incorporating PUR data into analyses of pesticide impacts on wildlife have appeared in the scientific literature (2–4). For example, Davidson (2) analyzed the association between declining populations of amphibians in California and pesticide use. Many granting agencies have taken on the challenges of risk analysis to wildlife in association with pesticide use, such as the project funded by the CALFED Bay-Delta Program (5), and PUR data played an important role in the analyses.

Suggestions on Using the PUR To Evaluate Pesticide Exposures to Endangered Species Data from the PUR could be used in a number of ways to improve the estimates of exposure of endangered species to pesticides described in biological opinions prepared by the National Marine Fisheries Service (NMFS) (6). Currently, NMFS scientists make a number of assumptions related to pesticide use in salmonid-supporting watersheds that in aggregate result in overestimates of pesticide applications and subsequent salmonid exposure in those watersheds. For example, potential exposure scenarios are based on the assumption that pesticide products are applied at maximum labeled rates. Another assumption is that if an agricultural crop is listed on a product label, all agricultural land in specified watersheds delineated in the National Land Cover Database (7) will be treated with that product, whether or not that crop was grown in the watershed. Using the PUR data, one does not need to assume that maximum label rates were used or that any crop would be grown in any agricultural area. Rather, one can sort the PUR database to determine the amount of each pesticide active ingredient used in each square mile section in all areas of concern. PUR data exist for all years from 1990 to the present, so one can determine use over a wide range of realistic 96 In Pesticide Regulation and the Endangered Species Act; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.


environmental and economic conditions. Also, since the PUR data include the date of application, exposure assessments could examine use during times of the year when salmonids are vulnerable. Finally, the PUR data include the application method (air, ground, or other method), and this information could be important in determining, for example, the potential for drift into salmonid habitats. A PUR analysis would also help define the expected range of uses of each active ingredient in each area. NMFS is often most interested in worst-case exposure scenarios, and there are many ways PUR data could be analyzed so that such scenarios can be realistically described. First, statistical forecasting methods can be used to determine expected use in the future at the 95th or 99th (or other percentage) confidence interval of use based on historical use in watersheds of interest. Alternatively, one could determine the probability distribution of each active ingredient’s use rates for a watershed. The 95th or 99th percentile use rate values could represent, at least, very high use rate scenarios. A high estimate of total pounds applied could then be calculated by multiplying the high percentile rate of use by total area of the crops on which the product may be used. Unless PUR-based methods are available and can support alternative methodologies for determining pesticide use in salmonid-bearing watersheds, one might still want to use NMFS’s current method to set a maximum use rate. The PUR data are less useful for pesticides applied in urban settings, since not all such use is required to be reported. However, one could use the pesticide sales database, another database administered by DPR (8) to estimate urban pesticide use. Sales of all pesticides, urban and agricultural, are reported to DPR. Thus, dividing the total agricultural pounds reported in the PUR by the total pounds sold of a pesticide product gives the proportion representing agricultural use; one minus that proportion is the proportion used in urban areas. This, of course, is just an estimate since the sale of a pesticide does not necessarily mean it was actually used. Another limitation of the sales database is that sales are only reported for the entire state. To get urban use in some area, one could make an assumption that urban use is proportional to the population in that area.

References 1. 2. 3. 4. 5.

6.

Department of Pesticide Regulation. Pesticide Use Report (PUR); URL http:/ /www.cdpr.ca.gov/docs/pur/purmain.htm (accessed March 29, 2012). Davidson, C. Ecol. Appl. 2004, 14, 1892–1902. Davidson, C; Knapp, R. A. Ecol. Appl. 2007, 17, 587–597. Gervais, J. A.; Rosenberg, D. K.; Anthony, R. G. J. Wildl. Manage. 2003, 67, 155–164. Williams, M.; Hoogeweg, R. B.; Denton, D.; Zhang, M. Spatial and Temporal Quantification of Pesticide Loadings to the Sacramento River, San Joaquin River, and Bay-Delta to Guide Risk Assessment for Sensitive Species—Part I Project Status; SETAC North America, Portland, OR, Nov. 7–11, 2010. National Marine Fisheries Service. Endangered Species Act Section 7 Consultation Biological Opinion Environmental Protection Agency 97 In Pesticide Regulation and the Endangered Species Act; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.

7.


8.

Registration of Pesticides 2,4-D, Triclopyr BEE, Diuron, Linuron, Captan, and Chlorothalonil; URL http://www.nmfs.noaa.gov/pr/pdfs/ consultations/pesticide_opinion4.pdf (accessed March 29, 2012). Homer, C.; Dewitz, J.; Fry, J.; Coan, M.; Hossain, N.; Larson, C.; Herold, N.; McKerrow, A.; VanDriel, J. N.; Wickham, J. Photogramm. Eng. Remote Sens. 2007, 73 (4), 337–341. Department of Pesticide Regulation. Reports of Pesticide Sold in California; URL http://www.cdpr.ca.gov/docs/mill/nopdsold.htm (accessed March 29, 2012).

98 In Pesticide Regulation and the Endangered Species Act; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.

California Pesticide Use Data and Endangered Species - ACS

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