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PubMedDate not supplied

United States Department of Agriculture-Agricultural Research Service research on alternatives to methyl bromide: pre-plant and post-harvest.

Methyl bromide is a widely used fumigant for both pre-plant and post-harvest pest and pathogen control. The Montreal Protocol and the US Clean Air Act mandate a phase-out of the import and manufacture of methyl bromide, beginning in 2001 and culminating with a complete ban, except for quarantine and certain pre-shipment uses and exempted critical uses, in January 2005. In 1995, ARS built on its existing programs in soil-borne plant pathology and post-harvest entomology and plant pathology to initiate a national research program to develop alternatives to methyl bromide. The focus has been on strawberry, pepper, tomato, perennial and nursery cropping systems for pre-plant methyl bromide use and fresh and durable commodities for post-harvest use. Recently the program has been expanded to include research on alternatives for the ornamental and cut flower cropping systems. An overview of the national research program is presented. Results from four specific research trials are presented, ranging from organic to conventional systems. Good progress on short-term alternatives is being made. These will be used as the foundation of integrated management systems which begin with pre-plant management decisions and continue through post-harvest processing.

Agriculture↗
PubMed2005

Changes in soil C-isotopic composition in an agroecosystem under Free Air Carbon dioxide Enrichment (FACE) treatment during a crop rotation period.

FACE (Free Air Carbon dioxide Enrichment) has been used since 1999 to evaluate the effects of future atmospheric CO(2) concentrations on an arable crop agroecosystem. The experiment conducted at the Institute of Agroecology at the Federal Research Centre in Braunschweig consists of a typical local crop rotation of winter barley, a cover crop, sugar beet and winter wheat. The atmospheric CO2 concentration of ambient air is about 375 ppm with a delta13C value of -7 to -9 per thousand, and 550 ppm (delta13C value = -20.2 per thousand) during daylight hours in the rings fumigated with additional CO2. Thus, the surplus C can be traced in the agricultural system. Over the course of the first experimental period (3-year crop rotation period), the C-isotopic composition and the C concentration in soil were monitored monthly. Plant samples were analysed according to the relevant developmental stages of the crop under cultivation. A 13C depletion was observed in plant parts, as well as in soil samples from the FACE rings under CO2 enrichment, indicating that labelled C has reached both respective ecosystem compartments. Albeit farming management practice (especially ploughing) leads to a mixing of 'old' and 'new' C compounds throughout all soil horizons down to the end of the ploughing layer and resulted in a heterogeneous distribution of newly formed C compounds in the soil, isotope analysis of soil C reflected where the surplus C went.

Agriculture↗
PubMed2006

Sampling systems for isotope-ratio mass spectrometry of atmospheric ammonia.

Passive and active ammonia (NH(3)) sampling devices have been tested for their nitrogen (N) capture potential and delta(15)N fractionation effects. Several sampling techniques produced significantly different delta(15)NH(3) signals when sampling the same NH(3) source released from field site fumigation campaigns. Conventional passive NH(3)-monitoring systems have shown to provide insufficient N for isotope-ratio mass spectrometry and various modified devices have been developed, based on existing diffusion tube designs, to overcome this problem. The final sampler design was then tested in a wind tunnel to verify that sampling NH(3) in different environmental conditions did not significantly fractionate the delta(15)N signal.

Air Pollutants↗
PubMed1995

Possible side effects of airborne pesticides on fungi and vascular plants in The Netherlands.

A survey of the potential side effects of volatilized pesticides on fungi and vascular plants in The Netherlands has been made for two herbicides (atrazine and MCPA), a fungicide (captan) and a soil fumigant (metham sodium). By applying existing models, a prediction is presented of post-treatment dispersal and deposition due to volatilization, both at short and long ranges, and of the potential side effects on fungi and vascular plants. The general conclusion is that side effects (stunting and growth anomalies) are to be expected outside the target area, especially close (< 500 m) to treated plots with atrazine and metham sodium. In view of agricultural acreage in The Netherlands, these short-range effects may impinge on a relatively large scale. There may also be an impact at greater distances from treated plots, especially in the case of compounds that are slow to degrade such as MITC (methyl isothiocyanate), the active toxic moiety generated in soil from metham sodium.

2-Methyl-4-chlorophenoxyacetic Acid↗
PubMed1999

Subchronic and chronic toxicity of ingested 1,3-dichloropropene in dogs.

The potential toxicologic effects to dogs of 1,3-dichloropropene (1, 3-D), a soil fumigant used for the control of nematodes, were investigated. The 13-week subchronic toxicity study consisted of male and female beagle dogs (4/sex/dose group) given approximately 0, 5, 15, or 41 mg 1,3-D/kg body wt/day (approximately equivalent amounts of cis and trans isomers) via their diets. The 1-year chronic toxicity study consisted of male and female beagle dogs (4/sex/dose group) provided diets delivering approximately 0, 0.5, 2. 5, or 15 mg/kg body wt/day. The test material was stabilized in the feed by microencapsulation in a starch/sucrose matrix (80/20). In both the 13-week and the 1-year studies, the primary effect of 1,3-D in male and female dogs ingesting a dosage of >/=15 mg/kg/day was hypochromic, microcytic anemia. The anemia was regenerative, with increased erythropoietic activity characterized by polychromasia of erythrocytes and increased numbers of reticulocytes in peripheral blood. In the 13-week study, the anemia in dogs given 41 mg/kg/day progressively worsened over time, while the anemia in dogs given 15 mg/kg/day remained relatively constant between 42 and 90 days of dosing. Partial reversal of the anemia of high-dose animals occurred during a 5-week recovery period following the 13-week dosing regimen. In the 13-week study, terminal fasted body weights of males given 15 or 41 mg/kg/day were decreased 3 and 28%, respectively, and body weights of females given 5, 15, or 41 mg/kg/day were decreased 4.5, 12, and 24%, respectively, relative to controls. Males given 5 mg/kg/day for 13 weeks had no change in body weights relative to controls. In the 1-year study, the hypochromic microcytic anemia in dogs given 15 mg/kg/day remained relatively constant in severity between 3 and 12 months of treatment. Histopathologic alterations associated with anemia in the 1-year study consisted of increased hematopoiesis of the bone marrow and increased extramedullary hematopoiesis of the spleen. Body weights of males given 15 mg/kg/day were 5-12% lower than controls during the first 13 weeks of the study and 13-19% lower than controls during the remaining 9 months. Body weights of females given 15 mg/kg/day were 5-14% lower than controls over the majority of the dosing period. Males and females given 0.5 or 2.5 mg/kg/day for 1 year had no change in body weights relative to controls. A no-observed-effect level of 2.5 mg/kg/day was established for male and female dogs from the 1-year study.

Administration, Oral↗
PubMed1993

Cytotoxic and genotoxic activity of 1,3-dichloropropene in cultured mammalian cells.

1,3-Dichloropropene (DCP), a widely used soil fumigant previously found to be carcinogenic in both mice and rats, was evaluated for its cytotoxic and genotoxic effects in cultured rodent and human cells. A reduction of cell viability that was dependent on the dose and the length of treatment was observed with the trypan blue and the neutral red assay in both V79 cells and rat hepatocytes exposed to DCP concentrations ranging from 0.18 to 5.6 mM. In the absence of a metabolic activation system, a dose-dependent frequency of DNA single-strand breaks, that were only partially repaired within 24 hr, was revealed by the alkaline elution technique in V79 cells exposed to subtoxic DCP concentrations. The genotoxicity of DCP was confirmed by the results obtained in metabolically competent primary cultures of both rat and human hepatocytes which displayed similar dose-related amounts of DNA fragmentation and DNA repair synthesis, and showed, in comparison to metabolically deficient V79 cells, a somewhat greater sensitivity to the cytotoxic and DNA-damaging effects of DCP. The increase in the frequency of DNA breaks observed in rat hepatocytes after GSH depletion confirms the role of this tripeptide in DCP detoxification; its reduction in hepatocytes simultaneously exposed to metyrapone is consistent with a cytochrome P450-dependent biotransformation of DCP to more toxic metabolites.

Allyl Compounds↗
PubMed1998

Food preservation using ionizing radiation.

Irradiation processing has been researched extensively and is now in use worldwide for many food commodities. Irradiation has been successfully used to reduce pathogenic bacteria, eliminate parasites, decrease postharvest sprouting, and extend the shelf life of fresh perishable foods. Although food irradiation is widely accepted in world food markets, U.S. markets have been slower to accept the idea of irradiated food products. For fruits and vegetables, irradiation is not a cure for shelf life problems; cost and quality problems damage preclude its general use. It appears that the most likely use of irradiation in fruits and vegetables is as an insect control in those commodities for which there is no effective alternative method. For grains such as rice and wheat, irradiation has been used primarily to control insect infestation when insects have been shown to develop resistance to the traditional fumigation methods. Treatment of spices with irradiation doses of 10 kGy has proved to extend shelf life without causing significant changes in sensory or chemical quality. Higher doses that effectively sterilize spices, however, may cause undesirable chemical and sensorial changes. For meat, especially red meat, irradiation is considered a viable alternative in the effort to improve the safety of meat products. With time, the authors believe that economic realities and the technical superiority of irradiation for specific poultry products will lead to public acceptance of the process. Irradiation of seafood products is still being considered for approval by the USFDA, although it is currently used in Asian and European markets, especially for shrimp. It is our belief that scientifically based research in food irradiation and the positive results thereof will also prove economical in the twenty-first century. As we move to a more peaceful world with reduced threat of nuclear holocaust, these valid opinions will prevail and will overshadow the distortions and misinformation generated by the opponents of irradiation.

Animals↗
PubMed1990

Environmental chemistry of ethylene dibromide in soil and ground water.

Ethylene dibromide is a ground water pollutant principally as a result of its use as a soil pesticide and secondarily from spills or leaks of leaded gasoline in which it is an additive. The compound has been found in over 1900 wells in 4 countries: Japan, Israel, Australia, and the United States (10 states), typically at concentrations of 0.04-4 micrograms/L. The overall rate of detections in suspected areas is about 13%. Its use as a soil fumigant was banned in the US in 1983 because of its carcinogenicity. Concern over gasoline as a source should diminish as leaded fuels all but disappear from the market in many countries. The voluminous research and regulatory attention devoted to EDB has generated a picture, if not an entirely clear one, of how EDB behaves in the environment and what we can expect for the future. EDB is volatile, moderately water soluble, and has only weak equilibrium sorptive affinity for soil. Transport to ground water occurs by both vapor-phase diffusion and by advection with infiltrating water, depending on soil properties and precipitation and irrigation patterns. Models describing these processes have been developed and validated in part by laboratory experiments, but the complexity and heterogeneity of the field makes predictions difficult there. As with other pesticides, experience indicates that areas with permeable soils and shallow water tables are most vulnerable. However, EDB seems to have penetrated many tens of meters of unsaturated zone in some cases to reach the water table. Transport in ground water occurs with bulk water flow, subject to hydrodynamic dispersion effects common to all solutes, and subject to sorptive retardation. From equilibrium sorption partition coefficients, plume migration is likely to be a factor of 2-4 slower than bulk water flow. Hydrolysis is the most important abiotic reaction. The reaction is independent of pH in the range 4-9 and is probably uncatalyzed by particle surfaces. Both SN1 and SN2 mechanisms have been proposed. Estimates of the half-life range from 2-4 yr at 22-25 degrees C, to around two decades at 10 degrees C. These temperatures approximate subsurface conditions in warm climates (e.g., Florida) and temperate climates (e.g., New England), respectively. The major products are ethylene glycol and bromide ion. Both are of little concern at low concentrations. Vinyl bromide, which is a suspected carcinogen, is a minor product in lab studies, but so far there are no reports linking its presence with EDB in the field.(ABSTRACT TRUNCATED AT 400 WORDS)

Environmental Pollution↗
PubMed1992

Acute pesticide morbidity and mortality: California.

The California Pesticide Illness Surveillance Program collects, investigates, abstracts, and records reports received from physicians. A minority of the reports are received through the county health officers who are notified by physicians under a state requirement for reporting pesticide-caused conditions. Most of the cases are identified by review of workers' compensation records. All the cases identified are investigated by the agricultural commissioners of the counties where exposure occurred. The investigation reports are reviewed and abstracted by staff of the Worker Health and Safety Branch of the California Department of Pesticide Regulation, California Environmental Protection Agency (Cal/EPA). The crucial determination is assessment of the degree of relationship between the exposure and subsequent disease: definite, probable, possible, unlikely, or unrelated. In most years, the number of cases investigated has been between 2,500 and 3,000. Excluding antimicrobials, the number of cases found after investigation to have a definite, probable, or possible relationship with pesticide exposure has ranged from 970 (in 1989) to 1,372 (in 1988). Cases involving antimicrobials rarely were reported prior to 1987. In that year, surveillance staff began reviewing workers' compensation records personally, with the specific goal of identifying antimicrobial cases. Since then, antimicrobials have been found to account for 746-813 cases annually, primarily involving splashes and squirts to the eye and inhalation of fumes or vapors. Numbers of case reports from agricultural situations have varied irregularly, driven by small numbers of episodes concerning multiple individuals. Variability in numbers of cases involving the skin has depended almost entirely on variation in numbers of field worker dermatitis. The most common situation for field worker dermatitis has been summer work in table grapes grown in the southern San Joaquin valley. In the two years since reentry intervals for the acaricide propargite were lengthened, there have been no more major clusters of field worker dermatitis. Although the cases collected by the surveillance program are predominantly occupational, because of dependence on workers' compensation for case identification, most recorded deaths are nonoccupational. Nonoccupational fatalities include suicides, mistaken ingestion of pesticides (especially if stored in food containers), and entry into structures being fumigated. Occupational deaths are less common and more varied. The circumstances of each reported occupational death are summarized above.

California↗
PubMed1985

1,2-Dibromoethane initiation of hepatic nodules in Sprague-Dawley rats selected with Solt-Farber system.

Initiating effects of the fumigant 1,2-dibromoethane (DBE) for liver were examined using the Solt-Farber selection system. Male Sprague Dawley rats (230-260 g) were given one oral dose of DBE (75 mg/kg), a two-thirds partial hepatectomy 4 h later, five oral doses of 2-acetylamidofluorene (AAF) (25 mg/kg) on days 17-21, CCl4 (2 ml/kg) on day 22, a booster dose of AAF (10 mg/kg) on day 32, and were sacrificed on day 82. Nodules and appreciable gamma-glutamyl transpeptidase foci were found in the livers of four of six animals given DBE, but not in any animals of the control group.

2-Acetylaminofluorene↗
PubMed1993

Import control of irradiated foods by the thermoluminescence method.

A thermoluminescence (TL) method was applied for the import control of irradiated foods. The method is based on the determination of the TL of mineral contaminants in foods. Detection of irradiation was incorporated in official Finnish control procedures in spring 1990. For foodstuffs with a reduced microbe content and in which no fumigant residues are found, possible irradiation is investigated by the TL method. The minerals are separated from the foods in different ways: picking is used for spices; water rinsing for herbs, spices, berries and mushrooms; high-density liquid to separate the organic material from the mineral fraction in seafood; and carbon tetrachloride for foods forming gels with water. To date about 140 food samples have been analysed for control purposes: 50 samples of herbs and spices, 25 samples of berries and mushrooms and 65 samples of seafood. Of these, 14 samples of herbs and spices and 5 samples of seafood were shown to have been irradiated. Differences in TL intensity between irradiated and unirradiated samples were at least 1 and usually 3-4 orders of magnitude.

Animals↗
PubMed1991

Evaluation of a microbiological method for detection of irradiation of spices.

The suitability of a microbiological method, a combination of the direct epifluorescent filter technique (DEFT) and the total aerobic plate count (APC), for the detection of irradiation of spices was evaluated. The evaluation was carried out using different kinds of spices including peppers, paprika, cardamom, cinnamon, ginger; herbs such as thyme, marjoram, basil, and oregano; and garlic powder. Ground spices were tested as well as cut and whole spice samples. Samples were analysed before and after gamma-irradiation mainly with doses of 5 and 10 kGy. Two different methods (centrifugation, filtration) for sample pretreatment were compared. Differences between the DEFT count and the APC with doses of 5 and 10 kGy varied between 3.9 and 6.8 and between 5.7 and 7.5 log units, respectively. The duration of storage after irradiation had no effect on the microbiological results. When applied to fumigated samples, the method might cause confusion in the absence of chemical analyses. The results of the analyses of samples treated by an unknown process indicated that the method could, in fact, detect irradiated samples, although it could not differentiate between irradiated and heat-treated samples.

Bacteria↗
PubMed1980

Uptake of NO2 by plants grown at different salinity levels.

It is demonstrated that the uptake of nitrogen dioxide (NO2) by Phaseolus vulgaris L. is decreased by the addition of sodium chloride (NaCl) to the root medium, as a result of increased diffusive resistance of the leaves. The NO2-uptake rate constant measured kinetically was in agreement with the nitrite content of the leaves after the fumigation.

Biological Transport↗
PubMed1991

Genetic deficiency of human class mu glutathione S-transferase isoenzymes in relation to the urinary excretion of the mercapturic acids of Z- and E-1,3-dichloropropene.

Mononuclear lymphocytes were isolated from the blood of 12 individuals, who had been exposed to the vapour of the soil fumigant 1,3-dichloropropene (DCP). Western blot experiments were performed on the crude lymphocyte homogenates, using a monoclonal antibody against human hepatic glutathione S-transferase (GST) isoenzyme mu, to determine the presence or absence of mu-class isoenzymes mu and/or psi. Nine of the individuals were found to be positive for mu and/or psi, the remaining three individuals being negative. In addition, all individuals showed a positive staining on immunoblot of a protein of somewhat lower molecular mass than the hepatic standard. This protein was bound by the S-hexylglutathione affinity column, and presumably constitutes a new mu-class isoenzyme, which is not subject to genetic polymorphism. Determination of the specific activities of individual human GST isoenzymes towards Z-(cis-) and E-(trans-)-DCP demonstrated that mu-class isoenzymes show a considerably higher specific activity with Z-DCP than alpha-class or pi-class isoenzymes. In addition, mu-class isoenzymes were found to be 2- to 3-fold more active with Z-DCP than with E-DCP. Their activity towards E-DCP was similar to the specific activity of alpha-class isoenzymes. Genetic polymorphism for mu-class isoenzymes could thus be a determinant in the extent of excretion of mercapturic acids from Z- and E-DCP. The urinary excretion of Z- and E-DCP mercapturic acids and the respiratory exposure to Z- and E-DCP were determined for nine and eight phenotyped individuals, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcysteine↗
PubMed1992

Neoplastic expression in murine cells induced by halogenated hydrocarbons.

The neoplastic expression in mouse embryo fibroblasts exposed to 1,2-dibromoethane and its chloroanalogue, 1,2-dichloroethane in vitro, was examined. Both substances are widely used as fumigants for carpet and upholstery, as gasoline additives, and as organic solvents. Both are known to be highly toxic, mutagenic, and carcinogenic agents. C3H10T1/2 cells treated with these haloalkanes exhibited altered morphology and were selected further by cloning in soft agar. Soft agar clones were found to induce a 100% multitumor occurrence in the nude mouse model. These results suggest that this pair of mutagens have altered the normal phenotype of mouse embryo cells, and these cells have become neoplastic. These neoplastic cell lines will be useful as an in vitro model to study the role of genetic changes in the transformation processes induced by halogenated hydrocarbons.

Animals↗
PubMed1998

[Grain mites. A small epidemic caused by Pyemotes species].

Pyemotes mites, of which the grain itch mite is the most important for human medicine, are ectoparasites of many insect species. Human infestation occurs only accidentally and temporally. The source materials are most often grain, straw and plant-based foods. Bites produce an intensely itching urticarial wheal capped by pin-point vesicles, which often are destroyed by scratching. Pyemotes dermatitis favours the back, the abdomen and the flexor side of the forearms. The mites are barely visible to the naked eye and reside only briefly on humans and thus are not found by physicians during clinical examination. When itching starts, the parasites have usually left their hosts. Therefore it is important to investigate the patient's environment and to identify the infested materials. We describe an outbreak of Pyemotes dermatitis in at least 16 persons, most of them warehouse workers in a hobby mail-order house. Infested decorative wheat was the source of the problem. Successful eradication was achieved by fumigation of the storage facilities with the insecticide methylbromide. Our cases demonstrate the importance of examination of environmental specimens for ectoparasites in cases of unexplained dermatoses. Biological agriculture avoiding insecticides may cause reappearance of this almost forgotten skin disease.

Adult↗
PubMed1996

Vitality fertilization of Scots pine stands growing along a gradient of heavy metal pollution: short-term effects on microbial biomass and respiration rate of the humus layer.

In 1992 forest vitality fertilization experiments were established on a heavy metal deposition gradient with four treatments in three replications at distances of 0.5, 4 and 8 km from a Cu-Ni smelter in order to estimate their impact on the disturbed forest ecosystem. The increase in Cu concentration in the humus (F/H) layer of the Calluna site type Scots pine (Pinus sylvestris) stands from ca. 300 to 8000 mg kg(-1) d.m. (dry matter) along the 8 km long transect towards the smelter resulted in declining soil microbial biomass and soil respiration activity. Three independent measurements of microbial biomass: C(mic)-FE (fumigation extraction), C(mic)-SIR (substrate induced respiration), and ATP have been used together with an indicator of fungal biomass (ergosterol) and microbial activity (soil respiration). Within this Cu pollution range, all the measured microbial biomass levels declined to 10%-28% of the control plot values and activity assessed by respiration was lowered to 16%. Liming has increased the C(mic)-SIR and respiration rate. Treatments with test fertilizer, made from grounded apatite, did not result in different microbial biomass and respiration rate values compared to the respective controls along the whole gradient. Nitrogen + lime treatments resulted in similar changes to lime alone. No changes, as compared to the respective control, could be detected with nitrogen fertilization at the less polluted end of the gradient.

Journal Article↗
PubMed2003

Derivation of aquatic screening benchmarks for 1,2-dibromoethane.

Ethylene dibromide (1,2-dibromoethane or EDB) was primarily used in the United States as an additive in leaded gasoline and as a soil and grain fumigant for worm and insect control until it was banned in 1983. Historical releases of EDB have resulted in detectable EDB in groundwater and drinking wells, and recently concentrations up to 16 microg/L were detected in ground water at two fuel spill plumes in the vicinity of the Massachusetts Military Reservation Base on Cape Cod, Massachusetts. Because the ground water in this area is used to flood cranberry bogs for the purposes of harvesting, the U.S. Air Force sponsored the development of aquatic screening benchmarks for EDB. Acute toxicity tests with Pimephales promelas (fathead minnow), Daphnia magna, and Ceriodaphnia dubia were conducted to provide data needed for development of screening benchmarks. Using a closed test-system to prevent volatilization of EDB, the 48-h LC50S (concentration that kills 50% of the test organisms) for P. promelas, D. magna, and C. dubia were 4.3 mg/L, 6.5 mg/L, and 3.6 mg/L, respectively. The screening benchmark for aquatic organisms, derived as the Tier II chronic water quality criteria, is 0.031 mg EDB/L. The sediment screening benchmark, based on equilibrium partitioning, is 2.45 mg EDB/kg of organic carbon in the sediment. The screening benchmarks developed here are an important component of an ecological risk assessment, during which perhaps hundreds of chemicals must be evaluated for their potential to cause ecological harm.

Animals↗