Department of Pesticide Regulation Logo

Paul E. Helliker Director

Department of Pesticide Regulation


California Notice 2003-1

California State Seal
Gray Davis

Winston H. Hickox
Secretary, California
Protection Agency

July 1, 2002 THROUGH December 31, 2002

California regulations require the Department of Pesticide Regulation (DPR) to investigate all reports of possible adverse effects to people or the environment resulting from the use of pesticides. If an adverse impact occurred or is likely to occur, the regulations require DPR to reevaluate the registration of the pesticide.

Title 3, California Code of Regulations (CCR), section 6221, specifies the factors under which DPR may initiate a reevaluation: (a) public or worker health hazard, (b) environmental contamination, (c) residue over tolerance, (d) fish or wildlife hazard, (e) lack of efficacy,
(f) undesirable phytotoxicity, (g) hazardous packaging, (h) inadequate labeling, (i) disruption of the implementation or conduct of pest management, (j) other information suggesting a significant adverse effect, and (k) availability of an effective and feasible alternative material or procedure that is demonstrably less destructive to the environment. Often, ongoing DPR reviews trigger a reevaluation. Reevaluation triggers also include state and county pesticide use surveillance and illness investigations, pesticide residue sample analyses, environmental monitoring activities, and information from other state or federal agencies.

When a pesticide enters the reevaluation process, DPR reviews existing data. DPR requires registrants to provide additional data to determine the nature or the extent of the potential hazard or identify appropriate mitigation measures, if needed.

DPR concludes reevaluations in a number of different ways. If the data demonstrate that use of the pesticide presents no significant adverse effects, DPR concludes the reevaluation without additional mitigation measures. If additional mitigation measures are necessary, DPR places appropriate restrictions upon the use of the pesticide to mitigate the potential adverse effect. If the adverse impact cannot be mitigated, DPR cancels or suspends the registration of the pesticide product(s).

This report complies with the requirements of CCR section 6225. CCR section 6225 requires DPR to prepare a semiannual report describing pesticides evaluated, under reevaluation, or for which factual or scientific information was received, but no reevaluation was initiated. The report contains two sections:

I. Formal Reevaluation - initiated when an investigation indicates a significant adverse
impact has occurred or is likely to occur (page - 2); and

II. Preliminary Investigations (Evaluations) - products or active ingredients for which DPR receives possible adverse factual or scientific information, but no reevaluation has been initiated (page - 5).


Undertaken when investigations indicate that a significant adverse impact has occurred or is likely to occur.

BRODIFACOUM - 32 Products

Brodifacoum is registered in California to control rats and mice in residential, industrial, commercial, agricultural, and public buildings. Registrants formulate the product with a grain-based bait in pellets, mini-pellets, and wax blocks.

On December 30, 1999, at the request of the Department of Fish and Game (DFG), DPR placed pesticide products containing brodifacoum into reevaluation. DFG expressed concern that California's wildlife are exposed and may be adversely affected by currently registered uses of the anticoagulant rodenticide brodifacoum.

Since 1994, DFG's Pesticide Investigations Unit has investigated 58 cases of possible wildlife exposure to anticoagulant rodenticides. Residues of anticoagulant rodenticides were detected in 38 birds and mammals, and residues of brodifacoum were identified in 31 birds and mammals, accounting for 82 percent of the anticoagulant exposures. Of those individuals in which residues of brodifacoum were detected, clinical signs of anticoagulant poisoning were observed in 10 to 20 percent. Eleven of the animals also carried residues of at least one other anticoagulant rodenticide in conjunction with brodifacoum. Because wildlife typically retreats to dens, burrows, or unobtrusive roosts in the final stages of anticoagulant poisoning, exposure of nontarget wildlife to this compound may be more extensive. Most of the birds and mammals exposed to brodifacoum were recovered from areas adjacent to urban development in Santa Clara, Los Angeles, Ventura, Orange, San Benito, Alameda, and Contra Costa counties.

DPR and DFG staff met with representatives of the Rodenticide Registrant Task Force in April 2001. At that meeting, DPR agreed to review additional information submitted by the registrants. DPR's biologist has reviewed all data, slides, scientific journal articles, and correspondence submitted by the Rodenticide Registrant Task Force and other brodifacoum registrants. In October 2001, DPR learned that the U.S. Environmental Protection
Agency (U.S. EPA) was close to completing a final draft of its assessment of brodifacoum and difethialone. DPR plans to delay further processing of the brodifacoum reevaluation pending completion of U.S. EPA's assessment.

CHLOROPICRIN - 50 Products

Chloropicrin is a colorless liquid that volatilizes readily when released into the atmosphere. Chloropicrin has been used as an insecticide since 1917 and a soil fumigant since 1920. As a space and soil fumigant, chloropicrin controls nematodes, bacteria, fungi, insects, and weeds. Chloropicrin can be used alone or in combination with other fumigants such as telone or methyl bromide. Because of its strong odor, small amounts of chloropicrin are added to methyl bromide applications as a warning agent.

Data submitted to DPR under the Birth Defect Prevention Act indicate that chloropicrin has the potential to cause adverse health effects at low doses. The National Institute for Occupational Safety and Health (NIOSH) set an 8-hour time-weighted average (TWA) of
0.1 part per million (ppm) as the reference exposure limit (REL) for workers exposed to chloropicrin. The NIOSH standard of 0.1 ppm was recommended primarily for the prevention of eye irritation in humans.

Air monitoring data submitted by the Chloropicrin Manufacturers Task Force (CMTF) indicate that the air levels of chloropicrin at some distances from treated greenhouses or fields could exceed the NIOSH standard. In the CMTF studies, off-site movement of chloropicrin was monitored during and after soil fumigation using four application methods in three states. At the Arizona applications, considered to have meteorological conditions most comparable to a region in California, 4 of the 16 monitoring stations located 180 feet from the treated fields had chloropicrin levels at or exceeding the NIOSH standard. The highest level monitored was around 1,700 mg/m3 (i.e., 0.25 ppm). The flux or emissions of chloropicrin was also measured using the aerodynamic method. At the Arizona sites, the flux ranged from 114 to 222 mg/m2 /sec, or 12 to 25 percent of the chloropicrin applied during the highest 6-hour period. In addition, depending upon the aeration system used, the ambient air concentrations of chloropicrin near treated greenhouses could increase significantly following the required ventilation operation. A typical aeration would involve venting the greenhouse indoor air directly out to the exterior environment.

Pursuant to this reevaluation, DPR is requiring chloropicrin registrants to conduct and submit the results of various worker exposure and air quality monitoring studies from field and greenhouse applications. In May 2002, the Chloropicrin Manufacturers' Task Force submitted protocols for a worker exposure and air monitoring study and a vapor trapping efficiency study. DPR reviewed the protocols and the final results of the vapor trapping study are due in March 2003. The final results of the worker exposure and air monitoring study are due July 2004.

CYFLUTHRIN - 54 Products

The pesticide active ingredient cyfluthrin is a nonsystemic pyrethroid insecticide registered for use on numerous field, fruit, and vegetable crops, including citrus. In addition, DPR registers pesticide products containing cyfluthrin for use on lawns and ornamental plants, animals, and around industrial, institutional, agricultural, and household structures.

DPR initiated the reevaluation on May 8, 1998, based on its investigation of a May 1997 outbreak of respiratory irritation reported among orange harvesters exposed to residues of cyfluthrin in Tulare County and other pesticide illness reports related to cyfluthrin. As a part of the investigation of the Tulare County incident, DPR's Worker Health and Safety Branch conducted two separate inhalation-monitoring studies in orange groves during orange harvest. DPR determined that since dust and pollen are a part of the normal working environment, something different in the work environment led to the workers' respiratory irritation symptoms. DPR believes that the application of cyfluthrin to the citrus groves close to harvest led to the respiratory symptoms experienced. DPR compiled the results of its monitoring study in "Health and Safety Report, HS - 1765."

In mid-September 1998, the basic manufacturer of cyfluthrin submitted the results of several studies and journal articles concerning the respiratory irritation of cyfluthrin. On October 29, 1998, DPR met with the basic manufacturer to discuss the cyfluthrin reevaluation. At that meeting, DPR agreed to review the submitted studies and journal articles before deciding whether to require additional data.

DPR reviewed the results of three studies regarding respiratory irritation. In the mouse study, a NOEL of 5.4 mg/m3 was identified, which was based on the reduced respiratory rate noted at the 21.9 mg/m3 exposure level. In the rat study, at the lowest exposure level of 0.7 mg/m3, the respiratory rate was minimally reduced in comparison to the control animals. The author calculated a NOEL of 0.5 mg/m3. In the human study, human subjects were exposed under static conditions in which the initial exposure concentrations were reported to be 0.18 and 0.1 mg/m3 for the two exposure groups. Throat and nasal irritation was noted by 8 of the 10 subjects in both exposures. Due to several problems including the indeterminate concentration to which the subjects were exposed, a NOEL for sensory irritation could not be established. Since the rat is more sensitive than the mouse in regard to the irritating effects of cyfluthrin, the most appropriate NOEL appears to be the 0.5 mg/m3 derived from the rat study.

On August 16, 2001, DPR again met with the basic manufacturer to discuss the reevaluation of cyfluthrin. At the meeting, DPR agreed to review some additional new data before requiring further tests. In October 2001, the basic manufacturer submitted: (1) two worker exposure studies regarding hand harvesting of oranges and sweet corn; (2) four indoor exposure studies; and (3) a study entitled "Study on the RD50 Determination in Rats." Based on these data, DPR determined that no further structural monitoring data are required. However, a worker exposure study of hand harvesting sweet corn is still required. In September 2002, the basic manufacturer of cyfluthrin submitted a protocol for a corn exposure study, which will be conducted in the fall of 2002 and the spring of 2003. DPR reviewed and approved the protocol for the fall 2002 cyfluthrin corn study; however, the registrant was not able to secure an approprite site in which to conduct the study. The registrant has instead proposed that the studies be conducted in the spring and fall of 2003.

METHYL BROMIDE - 43 Products

Methyl bromide is a colorless and odorless gas that has been widely used since the 1940s as a preplant soil fumigant for controlling nematodes, plant pathogens, weeds, and insects. After harvest, it is used to protect crops from pest damage during storage and transportation. Methyl bromide is also used to eradicate wood-destroying pests in homes and other structures, and to control pests in mills, ships, railroad cars, and other transportation vehicles.

Since the early 1990s, DPR has focused considerable attention on ensuring the safe use of the fumigant methyl bromide. The Air Resources Board monitored during the 2000 methyl bromide use season to measure ambient air concentrations and ascertain whether they posed a threat to public health. Data indicate that short-term levels of methyl bromide were well within acceptable limits. However, data also indicate that ambient air concentrations in a number of locations exceeded DPR's target exposure level for seasonal (six- to eight weeks) exposures. DPR has determined that in certain high-use areas, the use of methyl bromide may cause an adverse impact. On June 26, 2001, DPR placed all products containing methyl bromide and allowing field fumigation into reevaluation based on the results of the 2000 monitoring data.

To determine the extent of seasonal exposure to methyl bromide in 2001, DPR required registrants to conduct ambient air quality monitoring in the Camarillo/Oxnard area of Ventura County and Santa Maria area of Santa Barbara County. The Alliance of the Methyl Bromide Industry (AMBI) completed its ambient air monitoring in October 2001 and submitted a final report in April 2002.

For 2002, DPR required methyl bromide registrants to conduct and submit the results of ambient air quality monitoring in Monterey/Santa Cruz and Ventura counties. Monitoring in Ventura County was completed in August 2002. Monitoring in Monterey and Santa Cruz counties was completed in October 2002. DPR expects the final reports of the monitoring to be submitted in the first quarter of 2003.


DPR conducts preliminary investigations on products for which DPR or other state or county agencies have identified possible hazards. As a result of evaluation, the investigations may lead to formal reevaluation.

On February 8, 2002, Mr. Michael Graf submitted a letter and several scientific articles to DPR on behalf of the Jumping Frog Research Institute, the League to Save Lake Tahoe, Californians for Alternatives to Toxics and Michael Graf as an individual. Mr. Graf requested that DPR place eight pesticide active ingredients into reevaluation - malathion, chlorpyrifos, diazinon, methidation, parathion, endosulfan, chlorothalonil, and trifluralin. Mr. Graf based this request on the submitted studies, which he feels demonstrate that the continued use and registration of these pesticides in California's Central Valley ".is likely to have a significant impact on the viability of amphibian species located in the Sierra Nevada."

DPR's scientists reviewed all of the submitted data and information. The authors of many of the articles agree that some amphibian populations in the Sierra Nevada are in decline and that the decline is the result of a multitude of factors. Declines and extinctions of certain amphibian populations have been reported worldwide, not just in California. Not all amphibian populations in the Sierra Nevada are in decline. Populations of the tree frog, Pseudacris (Hyla) regilla, do not appear to be in decline. While the submitted studies indicate that pesticide residues may be one of many factors contributing to amphibian decline, there is no direct confirmed evidence that pesticide residues are a major factor in amphibian deaths, or that a reduction or elimination of pesticide residues would reverse amphibian declines. After evaluating the submitted data, other data on file with DPR, and speaking with researchers studying amphibian populations, DPR determined that current data do not indicate a definitive link between the use of the above eight pesticides in the Central Valley and amphibian declines in the Sierra Nevada. Based on currently available data and information, DPR decided against placing the eight pesticides into reevaluation at this time.

For more information, please contact Ms. Ann Prichard, Senior Environmental Research Specialist in the Pesticide Registration Branch, by e-mail at <> or by telephone at (916) 324-3931.

original signed by Barry Cortez

January 4, 2003

Barry Cortez, Chief
Pesticide Registration Branch
(916) 445-4377


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