Applications Of Carbaryl Research Articles

MOF@Ag/AAB/Au@Ag composite matrix full-dimensional divergence effect-based SERS paper sensor for rapid carbaryl quantification.

Carbaryl is a broad-spectrum carbamate fungicide that may pose a threat to ecosystems and human health. To prevent and control the harm caused by excessive application of carbaryl, a full-dimensional divergence effect SERS sensor has been constructed. Biodegradable paper chips were used as sensor substrates. ZIF-8 with structural flexibility was grown in situ on carbon paper. A rough silver layer with surface like metal etching was clad outside the ZIF-8. Artificial antibody (AAB) with accurate grasping ability was polymerized on the surface of ZIF-8@Ag paper substrate. Au@Ag CSNPs were decorated on the AAB to provide abundant "hot spots". Every functional material layer works together to form a gap and tip region with superior plasmon resonance. The proposed SERS sensor realizes the rapid and accurate on-site screening and localization of carbaryl in food with good correlation responded in the range of 0.01-20μg·mL-1 and a low detection limit of 5.72×10-‍3‌ μg·mL-1.

Attract-and-kill for managing Popillia japonica (Coleoptera: Scarabaeidae) abundance and leaf injury in commercial vineyards.

Popillia japonica Newman (Coleoptera: Scarabaeidae) feeding negatively impacts many plant species, including grapes, potentially reducing fruit quality and yield. Chemical control, representing the current grower standard, relies on frequent broadcast applications of broad-spectrum insecticides, with alternative management strategies mostly lacking. Attract-and-kill (A&K) is a behavioral management strategy that combines semiochemical attractants and a killing agent on a substrate. This study assessed the impact of A&K on (i) the number of P. japonica adults and (ii) the percent of P. japonica feeding injury on grape foliage compared to the grower standard in commercial vineyards. This 2-year study was conducted at 3 commercial vineyards with 4 paired plots consisting of a grower standard control and an A&K treatment. The A&K treatment consisted of commercial lures, each placed on outside-edge grapevines, and weekly applications of carbaryl on the plants holding lures. The grower standard received broadcast insecticide applications at the grower's discretion. The A&K treatment experienced similar numbers of P. japonica adults and similar proportions of leaf injury compared to the grower standard. The use of A&K reduced by 96% the crop area treated with insecticides compared to the grower standard. The area treated by A&K was at the edge of the vineyards, where more leaf injury occurred regardless of treatment. A&K is a targeted approach that was effective at managing P. japonica and reducing chemical inputs on a small scale. It has the potential to be scaled up and refined to provide growers with a new management strategy.

Contributions of nearby agricultural insecticide applications to indoor residential exposures

BackgroundPesticide exposure has been associated with adverse health effects. We evaluated relationships between proximity to agricultural insecticide applications and insecticides in household dust, accounting for land use and wind direction. MethodsWe measured concentrations (ng/g) of nine insecticides in carpet-dust samples collected from 598 California homes. Using a geographic information system (GIS), we integrated the California Pesticide Use Reporting (CPUR) database to estimate agricultural use within residential buffers with radii of 0.5 to 4 km. We calculated the density of use (kg/km2) during 30-, 60-, 180-, and 365-day periods prior to dust collection and evaluated relationships between three density metrics (CPUR unit-based, agricultural land area adjusted, and average daily wind direction adjusted) and dust concentrations. We modeled natural-log transformed concentrations using Tobit regression for carbaryl, chlorpyrifos, cypermethrin, diazinon, and permethrin. Odds of detection were modeled with logistic regression for azinphos-methyl, cyfluthrin, malathion, and phosmet. We adjusted for season, year, occupation, and home/garden uses. ResultsChlorpyrifos use within 1–4 km was associated with 1 to 2-times higher dust concentrations in both the 60- and 365-day periods. Carbaryl applications within 2–4 km of homes 60-days prior to dust collection were associated with 3 to 7-times higher concentrations and the 4 km trend was strongest using the wind-adjusted metric (p-trend = 0.04). For diazinon, there were 2-times higher concentrations for the 60-day metrics in the 2 km buffer and for the CPUR and wind-adjusted metrics within 4 km. Cyfluthrin, phosmet, and azinphos-methyl applications within 4 km in the prior 365-days were associated with 2-, 6-, and 3-fold higher odds of detection, respectively. ConclusionsAgricultural use of six of the nine insecticides within 4 km is an important determinant of indoor contamination. Our findings demonstrated that GIS-based metrics for quantifying potential exposure to fugitive emissions from agriculture should incorporate tailored distances and time periods and support wind-adjustment for some, but not all insecticides.

Proximity to endocrine-disrupting pesticides and risk of testicular germ cell tumors (TGCT) among adolescents: A population-based case-control study in California.

The incidence of testicular germ cell tumors (TGCT) is increasing steadily in the United States, particularly among Latinos. TGCT is thought to be initiated in utero and exposure to endocrine-disrupting chemicals, suspected contributors to TGCT pathogenesis, during this critical developmental period may contribute to the rise. To assess the relationship between fetal exposure to agricultural endocrine-disrupting pesticides (EDPs) and TGCT risk among adolescents in a diverse population in California. We conducted a registry-based case-control study of TGCT. Cases, diagnosed between 1997 and 2011, were 15-19 years of age (n=381). Controls were matched on birth year and race/ethnicity (n=762). Quantities (kilograms) of 33 pesticides applied within 3 km and 1 km radii of each individual's address before birth were estimated using the Pesticide Use Reporting database. Odds ratios (OR), 95% confidence intervals (CI), and population attributable risk (PAR) were calculated for each EDP (using log-2 transformed values). Risk models considered race/ethnicity, birth year, and neighborhood socioeconomic status. A doubling of nearby acephate applications (3km and 1km radii) and malathion applications (1km radius) was associated with increased risks of TGCT among Latinos only (OR=1.09; 95% CI:1.01-1.17; 1.30; 95% CI:1.08-1.57, and 1.19; 95% CI:1.01-1.39, respectively), whereas application of carbaryl within a 3km radius increased TGCT risk in non-Latinos only (OR=1.14, 95% CI:1.01-1.28). We estimate that acephate was associated with approximately 10% of the TGCT PAR, malathion with 3% and carbaryl with 1%. TGCT among adolescents in California was associated with prenatal residential proximity to acephate and malathion among Latinos, and with carbaryl among non-Latinos. These results suggest that the rise in TGCT risk among Latinos may be associated with exposure to these pesticides.

Contributions of nearby agricultural insecticide applications to indoor residential exposures

BACKGROUND AND AIM: Pesticide exposure has been associated with adverse health effects; individuals may be exposed to pesticide drift from nearby agricultural fields. We evaluated relationships between agricultural insecticide applications and insecticide levels in carpet dust. METHODS: We measured concentrations (ng/g) of allethrin, azinphos-methyl, carbaryl, chlorpyrifos, cyfluthrin, cypermethrin, deltamethrin, diazinon, malathion, permethrin, phosmet, propoxur, tetramethrin in carpet-dust samples collected from 558 California homes. After using the California Pesticide Use Reporting database (reporting unit: ~2.59km2) to estimate agricultural insecticide use within buffers with radii of 0.5-, 1-, 2-, 3-, and 4km around each home, we calculated the density of use (kg/km2) during 30-, 60-, 180-, and 365-day periods prior to dust collection and evaluated relationships between insecticide density and concentrations in dust. We modeled natural-log transformed dust concentrations using Tobit regression for insecticides with 40% detection. For insecticides detected ≤40%, odds of detection were modeled with logistic regression. Models were adjusted for season, year, occupation, and home/garden uses. RESULTS:Detection frequencies ranged from 10% for allethrin, azinphos-methyl, and malathion to 80% for diazinon, chlorpyrifos, and permethrin. Chlorpyrifos applications within 1-4km of the residence during all time periods were associated with higher dust concentrations compared to homes without nearby applications. Carbaryl applications within 2-4km of homes 30- and 60-days prior to dust collection were associated with higher concentrations (30-days/2km, β any applications vs. none=8.2, 95%CI 1.8-37.6; 60-days/4km, β median density vs. none=4.2, 95%CI 1.1-15.7). Cyfluthrin and phosmet applications 180- and 365-days prior to dust collection were associated with higher odds of detection (365-days/4km, highest density vs. none: OR=2.2, 95%CI 1.2-4.0 and 6.2, 95%CI 3.3-12.0, respectively) compared to homes with no nearby use. CONCLUSIONS:Agricultural insecticide use within 4km of a home could be an important determinant of indoor contamination. Our findings provide valuable information for the development of exposure metrics for epidemiologic health studies. KEYWORDS: Pesticides, Exposures, Exposure assessment, Environmental epidemiology, Children's environmental health

Management of Hypsipyla robusta Moore (Pyralidae) damage in Chukrasia tabularis A. Juss (Meliaceae)

Chukrasia tabularis is a high-value tree in the mahogany family and in Vietnam is grown in home gardens and small plantations. One to 3-year old trees are susceptible to shoot tip damage from larvae of Hypsipyla robusta which feed inside the stem. With the recent expansion of C. tabularis plantations, the forestry sector is seeking management options for this pest. Therefore, the efficacy of a range of commercial insecticides and biological agents were evaluated in nursery and plantation experiments. Twenty days after application of carbaryl, carbosulfan, deltamethrin or fipronil to the shoots of 1-year old nursery seedlings, damage from inoculated H. robusta was reduced by 83–100%. Application of Bacillus thuringiensis, Beauveria bassiana or Metarhizium anisopliae were less effective, reducing damage by 58, 33 and 42%, respectively. In 2-year old trees in the field, damage from natural H. robusta infestation was reduced by >75% at 30 days after application of carbaryl, carbosulfan, deltamethrin or fipronil. Including alkyl sulfonate or trisiloxane ethoxylate as adjuvants into the spray mix reduced damage by up to 98%. Soil applied fipronil granules and foliar-applied B. thuringiensis were less effective treatments (72 and 63%, respectively). The most effective treatments can now be evaluated in more extensive trials so that management protocols can be provided to end-users.

Studying the efficacy of fipronil (GR 0.2%) against European Mole Cricket, Gryllotalpa gryllotalpa (Orthoptera: Gryllotalpidae)

The European Mole Cricket, Gryllotalpa gryllotalpa (Orthoptera: Gryllotalpidae), is a key pest of several crops in different regions of the world, damaging seedlings, roots and tubers. The efficacy of fipronil (Regent ® GR 0.2%) @ 2, 2.5 and 3 g/m2 along with toxic bait of carbaryl (EC 85%)@ 20 g/m2 were assessed against this pest in the field based on a completely randomized block design. Based on Henderson-Tilton formula, on the third day after treatment, the efficacy of fipronil @ 2, 2.5 and 3 g/m2 and carbaryl bait was 16%, 30%, 47% and 53%, respectively; while on the third day after treatment, the efficacy was 22%, 48%, 64% and 81%, respectively. At present, carbaryl application is banned in Iran; therefore, fipronil can be a suitable substitute for this insecticide.

Plasma cholinesterase activity as a biomarker for quantifying exposure of green sturgeon to carbaryl following applications to control burrowing shrimp in Washington State.

Willapa Bay (Washington State, USA) has been 1 of the rare intertidal locations where large-scale pesticide applications occur. Until recently, carbaryl was applied to control burrowing shrimp that decrease commercial oyster productivity. The bay is a critical habitat for green sturgeon (Acipenser medirostris), an anadromous species listed as threatened under the US Endangered Species Act. However, the hazard that carbaryl poses is unknown. Surrogate seawater-acclimated white sturgeon (A. transmontanus) were exposed to 0 μg L(-1) , 30 μg L(-1) , 100 μg L(-1) , 300 μg L(-1) , 1000 μg L(-1) , and 3000 μg L(-1) carbaryl for 6 h, and brain acetylcholinesterase (AChE) and plasma butyrylcholinesterase (BChE) activities were measured. Enzyme recovery was measured in an additional cohort exposed to 1000 μg L(-1) carbaryl for 6 h. Activity of AChE was reduced (p ≤ 0.001) at concentrations ≥ 100 μg L(-1) with recovery in the 1000 μg L(-1) cohort by 72 h. Surprisingly, BChE activity was greater than controls at concentrations ≥ 300 μg L(-1) (p > 0.05), a finding confirmed in additional fish exposed to 3000 μg L(-1) for 6 h (+30%, p < 0.001) with apparent recovery by 48 h. Plasma samples were collected from free-living green sturgeon before and 4 d to 5 d after application of carbaryl in Willapa Bay. Activity of BChE after application was reduced 28% (p < 0.001), indicating exposure to the pesticide. However, the lack of congruence between BChE and AChE activity in captive white sturgeon exposed to carbaryl indicates that further studies are needed to better understand the risk carbaryl exposure poses to green sturgeon. Environ Toxicol Chem 2016;35:2003-2015. © 2015 SETAC.

A psbA mutation (Val219 to Ile) causes resistance to propanil and increased susceptibility to bentazon in Cyperus difformis.

Propanil-resistant (R) Cyperus difformis populations were recently confirmed in California rice fields. To date, propanil resistance in other weed species has been associated with enhanced aryl acylamidase (AAA)-mediated propanil conversion into 3,4-dichloroaniline. Our objectives were to determine the level of propanil resistance and cross-resistance to other PSII inhibitors in C. difformis lines, and to elucidate the mechanism of propanil resistance. The propanil-R line had a 14-fold propanil resistance and increased resistance to bromoxynil, diuron and metribuzin, but not to atrazine. The R line, however, displayed a fourfold increased susceptibility to bentazon. Interestingly, susceptible (S) plants accumulated more 3,4-dichloroaniline and were more injured by propanil and carbaryl (AAA-inhibitor) applications than R plants, suggesting that propanil metabolism is not the resistance mechanism. psbA gene sequence analysis indicated a valine-219-isoleucine (Val219 Ile) amino acid exchange in the propanil-R chloroplast D1 protein. The D1 Val219 Ile modification in C. difformis causes resistance to propanil, diuron, metribuzin and bromoxynil but increased susceptibility to bentazon, suggesting that the Val219 residue participates in binding of these herbicides. This is the first report of a higher plant exhibiting target-site propanil resistance. Tank mixing of bentazon and propanil, where permitted, can control both propanil-R and propanil-S C. difformis and prevent the spread of the resistant phenotype. © 2016 Society of Chemical Industry.

Effect of pesticidal schedule to control the shoot and fruit borer Leucinodes orbonalis in brinjal

To study the performance of various pesticidal schedules to evolve a suitable management strategy against brinjal shoot and fruit borer, the field experiment was carried out at The Central Research Station, OUAT, Bhubaneswar from January to June 2010. The findings of investigation revealed that the brinjal shoot and fruit borer caused highest fruit damage (80.22%) at 120 days after transplanting under unprotected condition. Under protected condition, the mean fruit infestation due to shoot and fruit borer varied from 46.44 to 53.15 per cent. Among all the treatment schedule, application of cartap hydrochloride, monocrotophos, carbaryl, azadirachtin, Bt formulation and triazophos at 30, 45, 60, 75, 90 and 105 days after transplanting at 15 days interval reduced the fruit infestation successfully and registered highest fruit yield and highest monetary value (Rs. 36,070/ha).

Efficacies of Common Ready to Use Insecticides AgainstHalyomorpha halys(Hemiptera: Pentatomidae)

Efficacies of topical applications and dry residues of 9 common ready-to-use (RTU) insecticides were evaluated against brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) at intervals of exposure of 1 and 48 h. Permethrin and acetamiprid, were further evaluated to determine if H. halys recovered after an initial exposure. Topical applications of carbaryl, permethrin, insecticidal soap, petroleum oil, and acetamiprid, and residues of permethrin and acetamiprid increased mortality of adults. Topical applications of spinosad, essential oils, carbaryl, permethrin, insecticidal soap, petroleum oil, and acetamiprid, and residues of carbaryl, permethrin, and acetamiprid increased mortality of nymphs. Topical applications of carbaryl, neem oil, insecticidal soap, and acetamiprid increased egg mortality. In general, nymphs were more susceptible to insecticides than adults. Adult H. halys recovered after exposure to topical applications, but not dry residues of permethrin. Clearly, several RTU insecticides in the marketplace demonstrated potential to help gardeners manage H. halys.

Brain Acetylcholinesterase Activity in Shiner Perch (Cymatogaster aggregata) and Juvenile Chinook Salmon (Oncorhynchus tshawytscha) After Application of Carbaryl to Control Burrowing Shrimp Within Willapa Bay, Washington

Carbaryl has been applied in Willapa Bay, Washington, for five decades to control burrowing shrimp (Neotrypaea californiensis and Upogebia pugettensis) on commercial oyster (Crassostrea gigas) beds. Concerns about effects on nontarget species, including fishes, have led to restrictions in use despite a lack of data on in situ exposure. We measured brain acetylcholinesterase (AChE) activity in adult Shiner perch (Cymatogaster aggregata) and juvenile Chinook salmon (Oncorhynchus tshawytscha) after operational applications. We hypothesized that exposure in Shiner perch would be greater than in juvenile Chinook salmon because of their greater site fidelity and benthic foraging. However, Shiner perch exhibited no statistically significant AChE inhibition. Enzyme activity was statistically decreased (≤14%) in juvenile Chinook salmon after a second spray event; however, inhibition was less than that associated with overt effects and was similar to controls by 48h after the spray. Diet analyses confirmed that Shiner perch were primarily feeding on benthic invertebrates and that juvenile Chinook salmon were feeding primarily within the water column. Composition of Shiner perch diets and amount of food consumed varied little among channels and time periods; however, Shiner perch on beds consumed more food 6h after application than those at other time points and locations. There were no consistent differences in the diets of juvenile Chinook salmon within channels among time periods. Results suggest (1) that carbaryl applications pose little hazard to fish in the bay having habitat and dietary preferences similar to those of Shiner perch and juvenile Chinook salmon and (2) that quantification of direct exposure in the field is essential to adequately assess risk.

RNA interference revealed the roles of two carboxylesterase genes in insecticide detoxification in Locusta migratoria

Carboxylesterases (CarEs) play key roles in metabolism of specific hormones and detoxification of dietary and environmental xenobiotics in insects. We sequenced and characterized CarE cDNAs putatively derived from two different genes named LmCesA1 and LmCesA2 from the migratory locust, Locusta migratoria, one of the most important agricultural pests in the world. The full-length cDNAs of LmCesA1 (1892bp) and LmCesA2 (1643bp) encode 543 and 501 amino acid residues, respectively. The two deduced CarEs share a characteristic α/β-hydrolase structure, including a catalytic triad composed of Ser-Glu (Asp)-His and a consensus sequence GQSAG, which suggests that both CarEs are biologically active. Phylogenetic analysis grouped both LmCesA1 and LmCesA2 into clade A which has been suggested to be involved in dietary detoxification. Both transcripts were highly expressed in all the nymphal and adult stages, but only slightly expressed in eggs. Analyses of tissue-dependent expression and in situ hybridization revealed that both transcripts were primarily expressed in gastric caeca. RNA interference (RNAi) of LmCesA1 and LmCesA2 followed by a topical application of carbaryl or deltamethrin did not lead to a significantly increased mortality with either insecticide. However, RNAi of LmCesA1 and LmCesA2 increased insect mortalities by 20.9% and 14.5%, respectively, when chlorpyrifos was applied. These results suggest that these genes might not play a significant role in detoxification of carbaryl and deltamethrin but are most likely to be involved in detoxification of chlorpyrifos in L. migratoria.

Impact of four turf management regimes on arthropod abundance in lawns

Turfgrass management practices, especially the use of chemical pesticides, may be detrimental to beneficial arthropods such as predators and decomposers. However, little is known about the impact of other practices or pest control products on these beneficials. The impact of four different management regimes, consisting of synthetic pesticide cover sprays or combinations of more targeted applications of natural pesticides, on selected groups of non-targeted arthropods in lawns of different age was studied over 3 years. The short-term effect of diazinon and carbaryl on Carabidae and Collembola was also evaluated. Formicidae and Araneae were the most abundant taxa at both sites, representing 74-80% of total captures. With a few short-term exceptions, no persistent and significant difference between turfgrass management regimes on arthropod abundance was observed over the 3 year study. Diazinon and carbaryl significantly reduced Carabidae abundance, but only one year out of three, while Collembola abundance was only transiently affected by carbaryl application in 2003. The study showed that practices and products used in the four management regimes did not disrupt the populations of specific groups of arthropods. These results provide useful information to professionals for the development of ecological turf practices to maintain beneficial arthropod abundance and diversity in urban landscapes.

Effects of carbaryl, chlorpyrifos and endosulfan on growth, reproduction and respiration of tropical epigeic earthworm, Perionyx excavatus (Perrier)

Effects of sub-lethal doses of carbaryl (1-Naphthyl-methylcarbamate), chlorpyrifos (O,O-diethyl O-3,5,6-trichloro-2-pyridinyl-phosphorothioate) and endosulfan (6,7,8,9,10,10-Hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin-3-oxide), respectively a carbamate, an organophosphate and an organochlorine insecticide on growth, reproduction and respiration of the tropical earthworm, Perionyx excavatus (Perrier) were investigated under laboratory conditions. The results showed significant reduction in biomass, production and hatching of cocoon and production of juveniles of the worms exposed to 0.75 to 3.03 mg/kg soil of carbaryl, 0.91 to 3.65 mg/kg soil of chlorpyrifos and 3.75 to 15.0 μg/kg soil of endosulfan corresponding to 12.5 to 50 % of LC50 value of the respective insecticide for P. excavatus. Endosulfan was found most dangerous among the three insecticides followed by carbaryl and chlorpyrifos. There was no hatching of the worms at endosulfan treatment 5.0 μg/kg soil (25 % LC50) or above while the highest dose of carbaryl and chlorpyrifos (50 % of LC50) rendered respectively 87.13 and 24.84 % reductions in hatching as compared to control. Chlorpyrifos produced no change in respiration of the worms except at the highest dose, while the worms showed an increase in evolution of CO2 at all doses of carbaryl and endosulfan. Based on the recommended agricultural dose of each insecticide, it was concluded that application of endosulfan and carbaryl was potentially dangerous to earthworms.

Effects of Carbaryl and 1-Naphthol on Soil Population of Cyanobacteria and Microalgae and Select Cultures of Diazotrophic Cyanobacteria

Carbaryl application to soil collected from a rice fallow field was relatively less toxic to viable estimates of cyanobacteria and microalgae under nonflooded conditions than under flooded conditions. Application of 1-naphthol, the hydrolysis product of carbaryl, to soil under both the regimes increased the population of both cyanobacteria and microalgae. Soil application of carbaryl and 1-naphthol in combination, up to 1.0kgha(-1), was nontoxic to the viable population. The toxicity exerted by carbaryl and 1-naphthol towards growth, measured in terms of chlorophyll a, and nitrogenase activity was more pronounced in Anabaena spp. than in Nostoc spp.

Comparative effect of integrated pest management and farmers' standard pest control practice for managing insect pests on cabbage (Brassica spp.)

Studies were conducted on experimental cabbage plantings in 2009 and on experimental and commercial plantings in 2010, comparing farmers' current chemical standard pesticide practices with an integrated pest management (IPM) program based on the use of neem (Aza-Direct) and DiPel (Bacillus thuringiensis). In experimental plantings, the IPM program used six or eight applications of neem and DiPel on a rotational basis. The standard-practice treatments consisted of six or eight applications of carbaryl and malathion or control treatment. The IPM treatments reduced pest populations and damage, resulting in a better yield than with the standard chemical or control treatment. When IPM treatment included three applications of neem plus three applications of DiPel (on a rotational basis in experimental fields), it again reduced the pest population and damage and produced a better yield than the standard practice. The lower input costs of the IPM program resulted in better economic returns in both trials. The IPM components neem and DiPel are suitable for use in an IPM program for managing insect pests on cabbage (Brassica spp.).

Comparison of14C-radioactivity in rice-paddy soil exposed to atmospheric and elevated CO2conditions after14C-carbaryl treatment

This study was performed to investigate if elevated affects the residue pattern of in the soil environment after -carbaryl treatment -carbaryl was applied on the rice plant-grown greenhouse soil exposed to atmospheric and elevated conditions. -radioactivity was measured in the rhizospheric soil and rice straw samples six months after -carbaryl application. Significantly high radioactivity was observed in the soil exposed to atmospheric as compared to that in the soil exposed to elevated C(h. Background level of radioactivity was observed in rice plant samples. These observations suggest the possibility that elevated may affect residual radioactivity of -carbaryl in the soil rather than that in the plant.

Utility of Nicotiana tabacum Cell Suspension Cultures Expressing Human CYP1A1, CYP1A2 and CYP3A4 to Study the Oxidative Metabolism of the Herbicide 14C-Fluometuron

The metabolism and biotransformation of the (14)C-labeled phenylurea herbicide fluometuron was examined using tobacco cell suspension cultures transformed separately with human cyp1a1, cyp1a2 and cyp3a4, and corresponding non-transformed cultures in order to screen and predict metabolic patterns. Experimental parameters modified were concentration of (14)C-fluometuron, incubation period, and additional application of inhibitor carbaryl. Media and cell extracts were analyzed by radio-TLC and radio-HPLC, isolated metabolites by LC-MS, and non-extractable residues by combustion. During 48 hours, the CYP1A1 expressing cultures metabolized 90.0 % of applied fluometuron, while the non-transgenic controls transformed 67.0 %. The CYP1A2 expressing cultures exhibited highest rates (95.1 %), CYP3A4 expressing cultures lowest rates (43.0 %). The primary metabolites identified were mono-demethyl (main metabolite in controls) and di-demethyl fluometuron (mainly in CYP1A2 cultures), besides a non-identified primary product (mainly in CYP1A1 cultures); metabolic profiles differed distinctly among cultures. After addition of carbaryl, rates of fluometuron decreased noticeably in controls and not in CYP3A4 expressing cultures. This may indicate inhibition of endogenous tobacco P450s involved in fluometuron metabolism but not of CYP3A4. Additionally, the P450-transgenic cultures proved to be valuable tools to produce large amounts of metabolites for thorough identification.

Golfer Exposure to Chlorpyrifos and Carbaryl Following Application to Turfgrass

Exposure of golfers to pesticides following their application to turfgrass is of concern to regulators, turfgrass professionals, and consumers. Multipathway exposures were evaluated for golfers on turfgrass treated with chlorpyrifos and carbaryl. Air concentrations and transferable foliar residues (TFRs) were measured to assess potential respiratory and dermal exposures, respectively. At the same time, exposure to individuals simulating the play of golf was determined by dosimetry and urinary biomonitoring. Individual golfer exposure was determined in 76 rounds of golf following eight applications of chlorpyrifos and two applications of carbaryl. Estimated exposures to golfers following full course and full rate applications of chlorpyrifos and carbaryl were 19-68 times below current U.S. EPA acute reference dose (Rfd) values, indicating safe exposures under U.S. EPA hazard quotient criteria. Dermal exposure was determined to be the dominant exposure pathway to golfers, accounting for approximately 60% of the chlorpyrifos absorbed dose and 100% of the carbaryl absorbed dose. This study also provides a set of transfer factors (TFs) that may be used to determine dermal exposure of golfers to pesticides using transferable residue data.