California Department of Pesticide Regulation

Fipronil is a relatively new insecticide that controls a broad spectrum of insects at low field application rates. It is a “new generation” insecticide because its mode of action, interference with the normal function of γ-aminobutyric acid (GABA)-gated channels, differs from the classical insecticides, such as organophosphates and carbamates, to which some insects have developed resistance. Fipronil is extensively used throughout the world and numerous studies have evaluated its toxicity and environmental fate. However, a concise review summarizing and combining the recent scientific findings available in the scientific literature is lacking even though the pesticide has been found to be highly toxic to some aquatic organisms. Thus, this document evaluates, summarizes, and combines important toxicological and environmental fate information from recent scientific articles and other literature to produce a detailed review of fipronil.

International public health workers are challenged by a burden of arthropod-borne disease that remains elevated despite best efforts in control programmes. With this challenge comes the opportunity to develop novel vector control paradigms to guide product development and programme implementation. The role of vector behaviour modification in disease control was first highlighted several decades ago but has received limited attention within the public health community. This paper presents current evidence highlighting the value of sub-lethal agents, specifically spatial repellents, and their use in global health, and identifies the primary challenges towards establishing a clearly defined and recommended role for spatial repellent products in disease control.

Nigrostriatal cell death in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease results from the inhibition of mitochondrial respiration by 1-methyl-4-phenylpyridinium (MPP+). MPP+ blocks electron flow from NADH dehydrogenase to coenzyme Q at or near the same site as do rotenone and piericidin and protects against binding of and loss of activity due to these inhibitors. The 4'-analogs of MPP+ showed increasing affinity for the site with increasing length of alkyl chain, with the lowest Ki, for 4'-heptyl-MPP+, being 6 microM. The 4'-analogs compete with rotenone for the binding site in a concentration-dependent manner. They protect the activity of the enzyme from inhibition by piericidin in parallel to preventing its binding, indicating that the analogs and piericidin bind at the same inhibitory site(s). The optimum protection, however, was afforded by 4'-propyl-MPP+. The lesser protection by the more lipophilic MPP+ analogs with longer alkyl chains may involve a different orientation in the hydrophobic cleft, allowing rotenone and piericidin to still bind even when the pyridinium cation is in a position to interrupt electron flow from NADH to coenzyme Q.

We present a method for calculating the Acute Insecticide Toxicity Loading (AITL) on US agricultural lands and surrounding areas and an assessment of the changes in AITL from 1992 through 2014. The AITL method accounts for the total mass of insecticides used in the US, acute toxicity to insects using honey bee contact and oral LD50 as reference values for arthropod toxicity, and the environmental persistence of the pesticides. This screening analysis shows that the types of synthetic insecticides applied to agricultural lands have fundamentally shifted over the last two decades from predominantly organophosphorus and N-methyl carbamate pesticides to a mix dominated by neonicotinoids and pyrethroids. The neonicotinoids are generally applied to US agricultural land at lower application rates per acre; however, they are considerably more toxic to insects and generally persist longer in the environment. We found a 48- and 4-fold increase in AITL from 1992 to 2014 for oral and contact toxicity, respectively. Neonicotinoids are primarily responsible for this increase, representing between 61 to nearly 99 percent of the total toxicity loading in 2014. The crops most responsible for the increase in AITL are corn and soybeans, with particularly large increases in relative soybean contributions to AITL between 2010 and 2014. Oral exposures are of potentially greater concern because of the relatively higher toxicity (low LD50s) and greater likelihood of exposure from residues in pollen, nectar, guttation water, and other environmental media. Using AITL to assess oral toxicity by class of pesticide, the neonicotinoids accounted for nearly 92 percent of total AITL from 1992 to 2014. Chlorpyrifos, the fifth most widely used insecticide during this time contributed just 1.4 percent of total AITL based on oral LD50s. Although we use some simplifying assumptions, our screening analysis demonstrates an increase in pesticide toxicity loading over the past 26 years, which potentially threatens the health of honey bees and other pollinators and may contribute to declines in beneficial insect populations as well as insectivorous birds and other insect consumers.

A risk assessment of the triazine herbicide atrazine has been conducted by first analyzing the toxicity database and subsequently estimating exposure. Margins of safety (MOS) were then calculated. Toxicity was assessed in animal studies and exposure was estimated from occupational and dietary sources. In acute toxicity studies, atrazine caused developmental toxicity in the rabbit [no observed effect level (NOEL) 5 mg kg(-1) day(-1)] and cardiotoxicity in a dog chronic study (NOEL 0.5 mg kg(-1) day(-1)); cancer (mammary glands) resulted from lifetime exposure. The mammary tumors, which occurred specifically in female Sprague-Dawley rats, were malignant, increased in a dose-dependent manner and were also observed with other, related triazines. Evidence for a genotoxic basis for these tumors was either equivocal or negative. Triazines have been shown to be clastogenic in Chinese hamster ovary cells, in vitro, but without showing a convincing dose/response relationship. Atrazine can be converted into genotoxic N-nitrosoatrazine in the environment or the digestive system, suggesting that N-nitrosamines derived from triazines could be oncogenic. However, it was concluded that N-nitrosotriazines are unlikely to play a significant role in triazine-induced rat mammary gland tumors. An endocrine basis for the mammary tumors, involving premature aging of the female SD rat reproductive system, has been proposed. A suppression of the luteinizing hormone surge during the estrus cycle by atrazine leads to the maintenance of elevated blood levels of 17beta-estradiol (E2) and prolactin. The mechanism for tumor development may include one or more of the following: the induction of aromatase (CYP19) and/or other P450 oxygenases, an antagonist action at the estrogen feedback receptor in the hypothalamus, an agonist action at the mammary gland estrogen receptor or an effect on adrenergic neurons in the hypothalamic-pituitary pathway. None of these has been excluded as a target because there has been a lack of a rigorous attempt to address the mechanism of action for mammary tumors at the molecular level. The potential occupational exposure to atrazine was assessed during mixing, loading and application. Absorbed daily dosage values were 1.8-6.1 microg kg(-1) day(-1). The MOS values (animal NOEL/human exposure) for short-term (acute) exposure were 820-2800. Longer-term occupational exposure and risk were also calculated. Detectable crop residues are generally absent at harvest. Theoretical calculations of acute dietary exposure used tolerance levels, along with secondary residues, and water, for which there is a maximum contamination level; atrazine plus the three main chlorotriazine metabolites were combined. MOS values were above 2000 for all population subgroups. Dietary exposure to atrazine is therefore extremely unlikely to result in human health hazard. Recent publications have reported a possible feminization of frogs, measured in laboratory and field studies. This is assumed to be due to the induction of aromatase, but no measurements of enzyme activity have been reported. In field studies, the water bodies with the greatest numbers of deformed frogs sometimes had the lowest concentrations of atrazine. Other studies have also cast doubt on the feminization theory, except perhaps at very high levels of atrazine. Epidemiology studies have investigated the possibility that atrazine may result in adverse effects in humans. Although some studies have claimed that atrazine exposure results in an elevated risk of prostate cancer, the published literature is inconclusive with respect to cancer incidence.

ADVERTISEMENT RETURN TO ISSUEPREVFeatureNEXTPeer Reviewed: Meeting the Scientific Needs of Ecological Risk Assessment in a Regulatory ContextThree strategies could move both science and regulation forwardSteven P. Bradbury, Tom C. J. Feijtel, and Cornelis J. Van LeeuwenCite this: Environ. Sci. Technol. 2004, 38, 23, 463A–470APublication Date (Web):December 1, 2004Publication History Published online1 December 2004Published inissue 1 December 2004https://doi.org/10.1021/es040675sRIGHTS & PERMISSIONSArticle Views1952Altmetric-Citations97LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (157 KB) Get e-AlertsSUBJECTS:Risk assessment Get e-Alerts

Pollutants in agricultural irrigation return flow (tailwater) constitute a significant nonpoint source of pollution in intensive agricultural regions such as the Central Valley of California. Constructed wetlands (CWs) represent a feasible mitigation option to remove pollutants including pesticides in the tailwater. In this study, we evaluated two CWs in the Central Valley for their performance in removing pyrethroid and organophosphate insecticides under field-scale production conditions. Both CWs were found to be highly effective in reducing pyrethroid concentrations in the tailwater, with season-average concentration reductions ranging from 52 to 94%. The wetlands also reduced the flow volume by 68-87%, through percolation and evapotranspiration. When both concentration and volume reductions were considered, the season-average removal of pyrethroids ranged from 95 to 100%. The primary mechanism for pyrethroid removal was through sedimentation of pesticide-laden particles, which was influenced by hydraulic residence time and vegetation density. Temporal analysis indicates a potential efficiency threshold during high flow periods. The season-average removal of chlorpyrifos ranged 52-61%. The wetlands, however, were less effective at removing diazinon, likely due to its limited sorption to sediment particles. Analysis of pesticide partitioning showed that pyrethroids were enriched on suspended particles in the tailwater. Monitoring of pesticide association with suspended solids and bed sediments suggested an increased affinity of pyrethroids for lighter particles with the potential to move further downstream before subject to sedimentation. Results from this study show that flow-through CWs, when properly designed, are an effective practice for mitigating hydrophobic pesticides in the irrigation tailwater.

Although people of color and low-income groups bear a disproportionate share of the health risks from exposure to pesticides, research attention has been meager, and data on acute and chronic health effects related to their toxic exposures are generally lacking. Increased resources are needed both to study this issue and to mitigate problems already identified. People of color should be a major research focus, with priority on long-term effects, particularly cancer, neurodevelopmental and neurobehavioral effects, long-term neurological dysfunction, and reproductive outcome. Suitable populations at high risk that have not been studied include noncertified pesticide applicators and seasonal and migrant farm workers, including children.

The California Air Resources Board conducted ambient air monitoring of pesticides in support of the California Department of Pesticide Regulation toxic air contaminant program. Monitoring was done in several communities in a county of high use during the month of expected peak use of a particular pesticide in order to assess general population exposure. Additional sampling was conducted adjacent to specific agricultural applications to assess maximum short-term concentrations to which the public might be exposed. Medium and low volume samplers were used with appropriate collection media (e.g., Teflon filters, XAD-2 adsorbent resin), followed by laboratory analysis. Concentrations measured around specific applications would be expected to be representative of other areas, especially in California, with comparable application rates, crops, and weather conditions. Since the program began in 1986, monitoring has been conducted for 22 pesticides. Results for three soil fumigants were of potential public health concern and led to the suspension of permits for the use of one pesticide and were used in the development of use modifications and buffer zones for two others.

We outline an approach to pesticide risk assessment that is based upon surveys of pesticide use throughout West Africa. We have developed and used new risk assessment models to provide, to our knowledge, the first detailed, geographically extensive, scientifically based analysis of pesticide risks for this region. Human health risks from dermal exposure to adults and children are severe enough in many crops to require long periods of up to three weeks when entry to fields should be restricted. This is impractical in terms of crop management, and regulatory action is needed to remove these pesticides from the marketplace. We also found widespread risks to terrestrial and aquatic wildlife throughout the region, and if these results were extrapolated to all similar irrigated perimeters in the Senegal and Niger River Basins, they suggest that pesticides could pose a significant threat to regional biodiversity. Our analyses are presented at the regional, national and village levels to promote regulatory advances but also local risk communication and management. Without progress in pesticide risk management, supported by participatory farmer education, West African agriculture provides a weak context for the sustainable intensification of agricultural production or for the adoption of new crop technologies.

Journal Article Fungicides, An Advanced Treatise Get access Fungicides, An Advanced Treatise., Vol1. Torgeson Dewayne C., (Ed.). Academic PresS, New York, 1967. vx+697 pp. Price $29.00. E P Carter E P Carter Pesticides Regulation Division U.S. Department of Agriculture Search for other works by this author on: Oxford Academic Google Scholar Journal of Association of Official Analytical Chemists, Volume 51, Issue 4, 1 July 1968, Page 952, https://doi.org/10.1093/jaoac/51.4.952 Published: 01 February 2020

ABSTRACT Three simplistic models are developed for evaluating the transport of organic pollutants through soil to ground water. The models consider mobility and first‐order degradation. The first calculates linear sorption/desorption of the pollutant and first‐order degradation without considering dispersion. The second is similar to the first but also considers dispersion. The third considers nonlinear sorption following a Freundlich equation and first‐order degradation but does not consider dispersion. The models are compared to field data for the pesticides aldicarb and DDT. The models projected a lower mobility for DDT than was observed in the field.

In this paper we present a broad overview of the class of insecticides known as synthetic pyrethroids. The discussion includes a summary of agricultural and urban pyrethroid use patterns and trends, pyrethroid chemical structure and properties, the significance of photostability to pyrethroid environmental fate, and hydrophobicity, persistence and relative aquatic toxicity as compared to other pesticides. Finally we provide a brief summary of California's regulatory response to recent detections of pyrethroids in aquatic sediments and a discussion of scientific and regulatory issues associated with ongoing pyrethroid aquatic exposure assessments and mitigation efforts.

Pesticides have been an essential part of agriculture to protect crops and livestock from pest infestations and yield reduction for many decades. Despite their usefulness, pesticides could pose potential risks to food safety and the environment as well as human health. This paper reviews the positive benefits of agricultural pesticide use as well as some potential negative impacts on the environment and food safety. In addition, using the case of California, we discuss the need for both residue monitoring and effective pest management to promote food safety. Twenty years' pesticide residue data from California's pesticide residue monitoring program were analyzed. Results showed that more than 95% of food samples were in compliance with US pesticide residue standards (tolerances). However, certain commodities from certain sources had high percentages of residues above tolerance levels. Even when residues above tolerance levels were detected, most were at levels well below 1 mg kg−1, and most posed negligible acute health risk. However, a few detected residues had the potential to cause health effects. Therefore, establishing an effective food residue monitoring program is important to ensure food quality throughout the marketplace.

Cogongrass is a weed throughout the tropics and subtropics. Introductions early this century have spread into forests, rangelands, reclaimed mined areas, roadsides, and natural ecosystems in the southeastern United States. Vegetative reproduction is the primary mechanism for survival and local spread, and sexually produced seeds of this obligate outcrossing species provide natural long-distance dispersal. Highly germinable (≥ 90%) seeds have no dormancy, though spikelet fill may be low (≤ 40%) in natural populations. Early seedling establishment, prior to rhizome development, is low (< 20%), occurring in areas with little competition; ≥ 75% bahiagrass sod cover is required to prevent cogongrass seedling establishment. Imazapyr and glyphosate are the most effective herbicides for cogongrass control. Younger cogongrass shoots are very susceptible to these herbicides; however, longer term control of adult plants requires translocation and thereby control of the rhizomes. Autumn applications of glyphosate and imazapyr provided greatest suppression of rhizome regrowth. Effective cogongrass management options exist and depend on integrating several control strategies. Mechanical control alone provides short-term control, whereas multiple discings plus herbicide application provide longer term control. Some combinations of herbicide, discing, and revegetation with desirable plant species provide excellent control. Because of the large geographic area infested with cogongrass and the often economically and environmentally unacceptable management techniques, biological control organisms also should be researched.

Urban pest control insecticides-specifically fipronil and its 4 major degradates (fipronil sulfone, sulfide, desulfinyl, and amide), as well as imidacloprid-were monitored during drought conditions in 8 San Francisco Bay (San Francisco, CA, USA) wastewater treatment plants (WWTPs). In influent and effluent, ubiquitous detections were obtained in units of ng/L for fipronil (13-88 ng/L), fipronil sulfone (1-28 ng/L), fipronil sulfide (1-5 ng/L), and imidacloprid (58-306 ng/L). Partitioning was also investigated; in influent, 100% of imidacloprid and 62 ± 9% of total fiproles (fipronil and degradates) were present in the dissolved state, with the balance being bound to filter-removable particulates. Targeted insecticides persisted during wastewater treatment, regardless of treatment technology utilized (imidacloprid: 93 ± 17%; total fiproles: 65 ± 11% remaining), with partitioning into sludge (3.7-151.1 μg/kg dry wt as fipronil) accounting for minor losses of total fiproles entering WWTPs. The load of total fiproles was fairly consistent across the facilities but fiprole speciation varied. This first regional study on fiprole and imidacloprid occurrences in raw and treated California sewage revealed ubiquity and marked persistence to conventional treatment of both phenylpyrazole and neonicotinoid compounds. Flea and tick control agents for pets are identified as potential sources of pesticides in sewage meriting further investigation and inclusion in chemical-specific risk assessments. Environ Toxicol Chem 2017;36:1473-1482. © 2016 SETAC.

This manuscript focuses on the toxicological evaluation of proteins introduced into GM crops to impart desired traits. In many cases, introduced proteins can be shown to have a history of safe use. Where modifications have been made to proteins, experience has shown that it is highly unlikely that modification of amino acid sequences can make a non-toxic protein toxic. Moreover, if the modified protein still retains its biological function, and this function is found in related proteins that have a history of safe use (HOSU) in food, and the exposure level is similar to functionally related proteins, then the modified protein could also be considered to be "as-safe-as" those that have a HOSU. Within nature, there can be considerable evolutionary changes in the amino acid sequence of proteins within the same family, yet these proteins share the same biological function. In general, food crops such as maize, soy, rice, canola etc. are subjected to a variety of processing conditions to generate different food products. Processing conditions such as cooking, modification of pH conditions, and mechanical shearing can often denature proteins in these crops resulting in a loss of functional activity. These same processing conditions can also markedly lower human dietary exposure to (functionally active) proteins. Safety testing of an introduced protein could be indicated if its biological function was not adequately characterized and/or it was shown to be structurally/functionally related to proteins that are known to be toxic to mammals.

Honey bees are important pollinators of agricultural crops. Pathogens and other factors have been implicated in high annual losses of honey bee colonies in North America and some European countries. To further investigate the relationship between multiple factors, including pathogen prevalence and abundance and colony health, we monitored commercially managed migratory honey bee colonies involved in California almond pollination in 2014. At each sampling event, honey bee colony health was assessed, using colony population size as a proxy for health, and the prevalence and abundance of seven honey bee pathogens was evaluated using PCR and quantitative PCR, respectively. In this sample cohort, pathogen prevalence and abundance did not correlate with colony health, but did correlate with the date of sampling. In general, pathogen prevalence (i.e., the number of specific pathogens harbored within a colony) was lower early in the year (January-March) and was greater in the summer, with peak prevalence occurring in June. Pathogen abundance in individual honey bee colonies varied throughout the year and was strongly associated with the sampling date, and was influenced by beekeeping operation, colony health, and mite infestation level. Together, data from this and other observational cohort studies that monitor individual honey bee colonies and precisely account for sampling date (i.e., day of year) will lead to a better understanding of the influence of pathogens on colony mortality and the effects of other factors on these associations.

t-[3H]Butylbicycloorthobenzoate [( 3H]TBOB; 22 Ci/mmol) was prepared by reductive dechlorination of its 4-chlorophenyl analog with tritium gas. This new radioligand binds reversibly to fresh washed rat brain P2 membranes in 500 mM NaCl plus 50 mM sodium-potassium phosphate buffer (pH 7.4) at 25 degrees C, with 80-90% specific relative to total binding, a KD of 61 +/- 15 nM, and a Bmax of 1.6 +/- 0.5 pmol/mg of protein. [3H]TBOB association with its binding site(s) is monophasic, but its dissociation is biphasic. The binding characteristics of [3H]TBOB are essentially identical to those of t-[35S]butylbicyclophosphorothionate [( 35S]TBPS) with respect to pH dependence, stimulation by anions, regional distribution in the brain, and pharmacological profile. Saturation analyses and dissociation studies further indicate that TBOB and TBPS have a common binding site. However, binding of the two radioligands differs in respect to temperature effects. In contrast to [35S]TBPS, which exhibits negligible binding at 0 degrees C, [3H]TBOB binds to rat brain membranes at 0, 25, and 37 degrees C with similar KD values. [3H]TBOB with its long radioactive half-life and temperature-independent KD is a valuable supplement to [35S]TBPS in further biochemical and pharmacological characterization of the gamma-aminobutyric acid receptor-ionophore complex.

BACKGROUND: Endosulfan has been used for over 50 years. Although most analogs have been discontinued, endosulfan has less environmental persistence. Nevertheless, pressure groups are lobbying for a worldwide ban. The reasons are: possible rodent male reproductive toxicity, other endocrine effects and cancer; human epidemiology, and exposure studies; residues appearing in remote areas of the world, e.g., the Arctic. METHODS: The endosulfan toxicology database is described and risks of its use assessed. RESULTS: Endosulfan is an antagonist at the GABA(A) receptor Cl(-) ionophore in mammalian CNS. Rat acute toxicity is moderate, LD(50)=48 (M) or 10 mg/kg/d (F), oral gavage; 130 (M), 70 mg/kg/d (F) dermal; LC(50)=34.5 microg/L (M), 12.6 microg/L (F), inhalation. Critical NOELs for risk assessment: acute oral (gavage)=0.7 mg/kg/d (rabbit developmental); Subchronic oral (diet)=1.2 mg/kg/d (rat reproduction); Chronic oral (diet)=0.6 mg/kg/d. There were no acceptable dermal toxicity studies. The critical acute and subchronic inhalation NOELs=0.001 mg/L, chronic inhalation=0.0001 mg/L (estimated). Toxicity to rat sperm occurred at doses causing neurotoxicity. Endocrine effects, resulting from P450 oxygenase(s) induction, were reversible. Increased cancer, genotoxicity, or histopathology in rodents was not observed in any organ. Possible effects on brain biogenic amine levels were probably secondary. CONCLUSIONS: Epidemiology and rodent studies suggesting autism and male reproductive toxicity are open to other interpretations. Developmental/ reproductive toxicity or endocrine disruption occurs only at doses causing neurotoxicity. Toxicity to the fetus or young animals is not more severe than that shown by adults.