Combining Headspace Solid-Phase Microextraction and Surface-Enhanced Raman Spectroscopy To Detect the Pesticide Fonofos in Apple Juice.

We developed an innovative approach that couples headspace solid-phase microextraction (SPME) with surface-enhanced Raman spectroscopy (SERS) to detect a volatile pesticide (i.e., fonofos) in a liquid complex matrix (i.e., apple juice). A gold nanoparticles-coated fiber was fabricated by reducing gold(III) on a chemically etched stainless steel wire to extract pesticide, using SPME. The fabricated fibers were then tested by a headspace-SPME method and a dip-SPME method, followed by SERS detection of fonofos in water and apple juice samples. Using the headspace-SPME method, we can detect as low as 5 ppb of fonofos in water and apple juice, compared with the dip-SPME method, which cannot detect lower than 10 ppb in water and 50 ppb in apple juice. This study demonstrated the potential capability of the headspace-SPME-SERS method for rapid (within 30 min) and sensitive detection of volatile and vaporizable compounds in complex matrices. The developed method could be a potential alternative approach to the gas chromatography method. Future work is needed to optimize the fiber by minimizing signal variation, and it should be tested in a variety of targeted compounds and matrices.

Pesticide application and detection in variable agricultural intensity watersheds and their river systems in the maritime region of Canada.

Applications of pesticides in areas of agricultural production have been an environmental concern for the past several decades. Varying-sized watersheds draining regions of intense agriculture in the Maritime Provinces of Canada were monitored between 2003 and 2007 to determine the major in-use pesticides and to gain an understanding of the risks posed to aquatic ecosystems. A questionnaire collected from farmers in one watershed intensively cropped with potato indicated that 43 pesticides were applied with 18 of them being detected in that watershed. Our results across the Maritime region suggested that detection frequencies ranged from 0.0 to 22 % during the study period. Chlorothalonil, linuron, metalaxyl, and metribuzin were detected in 17-22 % of samples collected during rainfall events every year. Other pesticides, such as azinphos-methyl, atrazine, cypermethrin, permethrin, fonofos, and ß-endosulfan were detected in ≤17 % of the samples during some years of the study. Concentrations of several pesticides were found to exceed their Canadian Council of Ministers of the Environment (CCME) aquatic life water-quality guidelines in pulses after rain events. The highest proportion of detections exceeding a CCME guideline was for chlorothalonil at 12.9 %, ß-endosulfan at 6.0 %, and linuron at 3.4 %. Despite indications that remedial measures offer protection to aquatic environments, spatial and temporal gaps in the data prevented a full evaluation. A dedicated long-term multiple-watershed monitoring program for this region of Canada is therefore recommended.

Fonofos poisons raptors and waterfowl several months after granular application.

From 1994 to 1999 in the Lower Fraser Valley region of southwest Canada, fonofos (Dyfonate G) was recommended for control of introduced wireworm (Agriotes spp.) pests on potato and other root crops. As part of a wildlife-monitoring program, we collected 15 raptors, including 12 bald eagles (Haliaeetus leucocephalus), found dead or debilitated on or near agricultural lands with severely inhibited brain and/or plasma cholinesterase activity and fonofos residues in ingesta. Bird remains, in nine cases waterfowl, were identified in the ingesta samples. Another seven bald eagles had severe cholinesterase inhibition, but without evidence of fonofos residues. During two winters from 1996 to 1998, 420 ha of potato fields, half of which had been treated the previous spring with fonofos and the remainder untreated, were searched weekly for evidence of wildlife mortality. Search efficiency was assessed with placed duck carcasses. Waterfowl outnumbered other species in field-use counts and comprised the greatest proportion of birds found dead. We found 211 wildlife remains, most scavenged; 35 intact carcasses were suitable for postmortem examination and/or toxicology analyses. Cholinesterase activity was assayed in brains of 18 waterfowl, five of which had severely depressed activity (average inhibition 74%; range, 69-78%). The gastrointestinal tract of a mallard found in a field treated with granular product contained 49 microg/g fonofos residues, linking waterfowl mortality with labelled use of the product. These findings demonstrate the risk of both primary and secondary poisoning by anticholinesterase insecticides where wildlife make intensive use of farmed fields.

Fonofos exposure and cancer incidence in the agricultural health study.

BACKGROUND: The Agricultural Health Study (AHS) is a prospective cohort study of licensed pesticide applicators from Iowa and North Carolina enrolled 1993-1997 and followed for incident cancer through 2002. A previous investigation in this cohort linked exposure to the organophosphate fonofos with incident prostate cancer in subjects with family history of prostate cancer. OBJECTIVES: This finding along with findings of associations between organophosphate pesticides and cancer more broadly led to this study of fonofos and risk of any cancers among 45,372 pesticide applicators enrolled in the AHS. METHODS: Pesticide exposure and other data were collected using self-administered questionnaires. Poisson regression was used to calculate rate ratios (RRs) and 95% confidence intervals (CIs) while controlling for potential confounders. RESULTS: Relative to the unexposed, leukemia risk was elevated in the highest category of lifetime (RR = 2.24; 95% CI, 0.94-5.34, Ptrend = 0.07) and intensity-weighted exposure-days (RR = 2.67; 95% CI, 1.06-6.70, Ptrend = 0.04), a measure that takes into account factors that modify pesticide exposure. Although prostate cancer risk was unrelated to fonofos use overall, among applicators with a family history of prostate cancer, we observed a significant dose-response trend for lifetime exposure-days (Ptrend = 0.02, RR highest tertile vs. unexposed = 1.77, 95% CI, 1.03-3.05; RRinteraction = 1.28, 95% CI, 1.07-1.54). Intensity-weighted results were similar. No associations were observed with other examined cancer sites. CONCLUSIONS: Further study is warranted to confirm findings with respect to leukemia and determine whether genetic susceptibility modifies prostate cancer risk from pesticide exposure.

Identification of fonofos metabolites in Latuca sativa, Beta vulgaris, and Triticum aestivum by packed capillary flow fast atom bombardment tandem mass spectrometry.

The metabolism of fonofos, a thiophosphonate insecticide, was investigated in mature lettuce (Latuca sativa), beet (Beta vulgaris), and wheat (Triticum aestivum). Six new metabolites were identified by LC-MS and LC-MS-MS analysis using fast atom bombardment (FAB) and packed capillary LC columns with application of the on-column focusing technique. These methods provided the sensitivity required to identify unknown metabolites that were present in the mature plants at only 20-230 ppb. Structural elucidation was facilitated by use of fonofos labeled with both carbon-14 and carbon-13 in the phenyl ring. In all three plants fonofos was converted to a glucose conjugate of thiophenoxylactic acid. Oxidation of the glucose conjugate gave isomeric sulfoxides in all species examined. Thiophenoxylactic acid was found esterified to malonic acid in lettuce. In beets, S-phenylcysteine was found as its malonic acid amide. A second metabolite unique to beets was N-(malonyl)-[2[(ethoxyethylphosphinothionyl)oxy]phenyl]cysteine. This novel structure was confirmed by synthesis.

Fonofos toxicosis and milk residues in dairy cattle.

An organophosphate toxicosis due to fonofos was diagnosed in an Iowa Dairy herd. Fonofos was detected in the feed source and in the rumen contents, liver, and kidney tissue of one cow that died acutely. Bulk tank milk contained detectable levels of fonofos.

Fonofos toxicosis in dairy cows: an accidental poisoning (1977).

An accidental poisoning (in 1977) of 28 Holstein cows occurred when approximately 0.9 kg of 25% active ingredient fonofos, O-ethyl S-phenyl ethylphosphonothiolothionate, was spilled onto bulk feed in a delivery truck. Eight cows died within 2 days; the remaining 20 were necropsied 29 days later. Of the 8 fatally poisoned, 7 were being fed a high-grain diet and 1 was fed a medium-grain diet. Fonofos concentrations in feed cart and storage bin samples were 100 micrograms/g and 61 micrograms/g, respectively. Tissues from 6 animals were analyzed extensively for fonofos concentrations: 2 had died immediately; the other 4 were in the recovery state when they were necropsied. Rumen contents and liver, kidney, brain, heart, and milk samples were analyzed. Fonofos concentrations in these samples were significantly higher in the cows fatally affected than in the cows necropsied 3 weeks later. The oral acute LD50 and LD1 of fonofos in Holstein cows were calculated by the Litchfield and Wilcoxon method to be 1.30 and 0.84 mg/kg, respectively, with a 95% confidence range of +/- 0.20 mg/kg.

The effect of fonofos and carbofuran on microbiological population, and persistence of fonofos in four organic soils infested with onion maggot.

One hundred days after field-application of fonofos as bands under the onion seed, 39 to 59% of that material was present in 3 moderately humified organic soils of pH varying from 5.4 to 6.7. In a low humified organic soil, only 21 to 24% of the applied fonofos remained. Thus humus enhanced the persistence of fonofos and curtailed the stimulating effect of fonofos on soil microbial populations. An assessment of low damage caused by onion maggot was found in a poorly humified soil with an even higher natural infestation than in a moderately humified soil. The effects of fonofos in other soils and of the low rate of carbofuran applied to four different types of soils on the numbers of fungi, bacteria, and actinomycetes were difficult to assess.

Confirmation of pesticide residue identity: part IX. Organophosphorus pesticides.

This paper describes a confirmation procedure for residue levels of dyfonate, dichlorofenthion and cyanox. After extraction and quantitation by flame photometric detector (FPD)-gas liquid chromatography (GLC), the organophosphorus pesticides are hydrolyzed in a 10% methanolic-potassium hydroxide solution. The phenolic hydrolysis products are then extracted from this solution and reacted with pentafluorobenzyl bromide to produce the pentafluorobenzyl (PFB) ether derivatives. These PFB ethers are subsequently cleaned-up and fractionated on a silica gel micro-column and analyzed by electron capture (EC)- GLC.