SEMIANNUAL REPORT SUMMARIZING THE REEVALUATION STATUS
OF PESTICIDE PRODUCTS DURING THE PERIOD OF
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).
I. FORMAL REEVALUATION
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
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
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.
II. PRELIMINARY INVESTIGATIONS (EVALUATIONS)
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 <email@example.com> or by telephone at (916) 324-3931.