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PubMed2003

Accelerated degradation of methyl iodide by agrochemicals.

The fumigant methyl iodide (MeI, iodomethane) is considered a promising alternative to methyl bromide (MeBr) for soil-borne pest control in high-cash-value crops. However, the high vapor pressure of MeI results in emissions of a significant proportion of the applied mass into the ambient air, and this may lead to pollution of the environment. Integrating the application of certain agrochemicals with soil fumigation provides a novel approach to reduce excessive fumigant emissions. This study investigated the potential for several agrochemicals that are commonly used in farming operations, including fertilizers and nitrification inhibitors, to transform MeI in aqueous solution. The pseudo-first-order hydrolysis half-life (t(1/2)) of MeI was approximately 108 d, while the transformation of MeI in aqueous solutions containing selected agrochemicals was more rapid, with t(1/2) < 100 d (t(1/2) < 0.5 d in some solutions containing nitrification inhibitors). The influence of these agrochemicals on the rate of MeI degradation in soil was also determined. Adsorption to soil apparently reduced the availability of some nitrification inhibitors in the soil aqueous phase and lowered the degradation rate in soil. In contrast, addition of the nitrification inhibitors thiourea and allylthiourea to soil significantly accelerated the degradation of MeI, possibly due to soil surface catalysis. The t(1/2) of MeI was <20 h in thiourea- and allylthiourea-amended soil, considerably less than that in unamended soil (t(1/2) > 300 h).

Adsorption↗
PubMed2004

Acaricidal activity of Paeonia suffruticosa root bark-derived compounds against Dermatophagoides farinae and Dermatophagoides pteronyssinus (Acari: Pyroglyphidae).

The acaricidal activities of materials derived from the root bark of Paeonia suffruticosa against adults of Dermatophagoides farinae and Dermatophagoides pteronyssinus were examined using direct contact and fumigation bioassays and compared with those of benzyl benzoate, dibutyl phthalate, and N,N-diethyl-m-toluamide (deet), widely used acaricides. The active constituents of Paeonia root bark were identified as paeonol and benzoic acid by spectroscopic analyses. On the basis of 24-h LD50 values, the acaricidal activities of paeonol (7.82 microg/cm3) and benzoic acid (6.58 microg/cm3) against adult D. farinae were comparable to that of benzyl benzoate (7.72 microg/cm3) but higher than those of deet (36.34 microg/cm3) and dibutyl phthalate (33.92 microg/cm3). Against adult D. pteronyssinus, the acaricidal activities of paeonol (7.08 microg/cm3) and benzyl benzoate (7.22 microg/cm3) were comparable to that of benzyl benzoate (7.14 microg/cm3). Deet and dibutyl phthalate were less effective. In fumigation tests with both mite species, paeonol and benzoic acid were much more effective in closed containers than open ones, indicating that the effect of these compounds was largely a result of action in the vapor phase. Neither benzyl benzoate, deet, nor dibutyl phthalate exhibited fumigant toxicity. Paeonia root bark-derived materials, particularly paeonol and benzoic acid, merit further study as potential acaricides or lead compounds for the control of D. farinae and D. pteronyssinus.

Acetophenones↗
PubMed2006

Dechlorination of chloropicrin and 1,3-dichloropropene by hydrogen sulfide species: redox and nucleophilic substitution reactions.

The chlorinated fumigants chloropicrin (trichloronitromethane) and 1,3-dichloropropene (1,3-D) are extensively used in agricultural production for the control of soilborne pests. The reaction of these two fumigants with hydrogen sulfide species (H2S and HS-) was examined in well-defined anoxic aqueous solutions. Chloropicrin underwent an extremely rapid redox reaction in the hydrogen sulfide solution. Transformation products indicated reductive dechlorination of chloropicrin by hydrogen sulfide species to produce dichloro- and chloronitromethane. The transformation of chloropicrin in hydrogen sulfide solution significantly increased with increasing pH, indicating that H2S is less reactive toward chloropicrin than HS- is. For both 1,3-D isomers, kinetics and transformation products analysis revealed that the reaction between 1,3-D and hydrogen sulfide species is an S(N)2 nucleophilic substitution process, in which the chlorine at C3 of 1,3-D is substituted by the sulfur nucleophile to form corresponding mercaptans. The 50% disappearance time (DT50) of 1,3-D decreased with increasing hydrogen sulfide species concentration at a constant pH. Transformation of 1,3-D was more rapid at high pH, suggesting that the reactivity of hydrogen sulfide species in the experimental system stems primarily from HS-. Because of the relatively low smell threshold values and potential environmental persistence of organic sulfur products yielded by the reaction of 1,3-D and HS-, the effects of reduced sulfide species should be considered in the development of alternative fumigation practices, especially in the integrated application of sulfur-containing fertilizers.

Allyl Compounds↗
PubMed2005

Use of composted animal manures to reduce 1,3-dichloropropene emissions.

Atmospheric emission of the soil fumigant 1,3-dichloropropene (1,3-D) has been associated with the deterioration of air quality in certain fumigation areas. To minimize the environmental impacts of 1,3-D, feasible and cost-effective control strategies are in need of investigation. One approach to reduce emissions is to enhance the surface layer of a soil to degrade 1,3-D. A field study was conducted to determine the effectiveness of composted steer manure (SM) and composted chicken manure (CKM) to reduce 1,3-D emissions. SM or CKM were applied to the top 5-cm soil layer at a rate of 3.3 or 6.5 kg m(-2). An emulsified formulation of 1,3-D was applied through drip tape at 130.6 kg ha(-1) into raised beds. The drip tape was placed in the center of each bed (102 cm wide) and 15 cm below the surface. Passive flux chambers were used to measure the loss of 1,3-D for 170 h after fumigant application. Results indicated that the cumulative loss of 1,3-D was about 48% and 28% lower in SM- and CKM-amended beds, respectively, than in the unamended beds. Overall, both isomers of 1,3-D behaved similarly in all treatments. The cumulative loss of 1,3-D, however, was not significantly different between the two manure application rates for either SM or CKM. The results of this study demonstrate the feasibility of using composted animal manures to control 1,3-D emissions.

Allyl Compounds↗
PubMed2005

Decontamination with vaporized hydrogen peroxide is effective against Mycobacterium tuberculosis.

AIMS: To determine the efficacy of room fumigation with vaporized hydrogen peroxide (VHP) in decontamination of viable Mycobacterium tuberculosis. METHODS AND RESULTS: About 8 x 10(4)-2.3 x 10(6) CFU of M. tuberculosis H37Rv and M. tuberculosis Beijing were dried in 10-microl drops in tissue culture plates, placed in steam-permeable Tyvek pouches and distributed on laboratory surfaces. The room was exposed to VHP delivered by air conditioning. Different exposure conditions were tested. Exposure to VHP resulted in sterilization of the bacterial samples in three different test runs. CONCLUSIONS: VHP treatment is an effective means of reducing and eliminating room contaminations of M. tuberculosis. SIGNIFICANCE AND IMPACT OF THE STUDY: Fumigation with VHP represents an alternative to formaldehyde fumigation, particularly for decontamination of animal rooms in tuberculosis research laboratories.

Anti-Bacterial Agents↗
PubMed2004

Insecticidal activity of plant essential oils against Pediculus humanus capitis (Anoplura: Pediculidae).

The insecticidal activity of 54 plant essential oils against female Pediculus humanus capitis De Geer was examined using direct contact and fumigation methods, and compared with the lethal activity of delta-phenothrin and pyrethrum, two commonly used pediculicides. In a filter paper contact bioassay with female P. humanus capitis, the pediculicidal activity was more pronounced in eucalyptus, marjoram, pennyroyal, and rosemary oils than in delta-phenothrin and pyrethrum on the basis of LT50 values at 0.0625 mg/cm2. At 0.125 mg/cm2, pediculicidal activity of cade, cardamone ceylon, clove bud, myrtle, rosewood, and sage oils was comparable with that of the test insecticides. In fumigation tests with female P. humanus capitis at 0.25 mg/cm2, eucalyptus, marjoram, pennyroyal, and rosemary oils were more effective in closed containers than in open ones, indicating that the effect of these oils was largely a result of action in the vapor phase. Neither delta-phenothrin nor pyrethrum exhibited fumigant toxicity. The essential oils described herein merit further study as potential control agents for P. humanus capitis.

Animals↗
PubMed1998

An unusual exposure to methyl bromide leading to fatality.

INTRODUCTION: Methyl bromide has been responsible for deaths that usually occur from its accidental inhalation during fumigation. CASE REPORT: We report an accidental fatality that occurred after methyl bromide seeped through underground conduits from a fumigated building to an adjacent guest house on the same property. The patient developed refractory seizures, intermittent fever, and multiorgan system failure before dying 19 days after exposure. The initial serum bromide was 27 mg/dL. Postmortem analysis detected methyl bromide concentrations of 2.9 mg/dL in the blood, 1.7 mg/dL in the bile, 24 micrograms/g in the liver, and 28 micrograms/g in the adipose tissue. CONCLUSION: Methyl bromide, although applied under acceptable safety standards, led to the inadvertent death of a young woman. Extreme care must be used when fumigating to insure no unsuspected seepage routes exist.

Adult↗
PubMed1992

A case of fatal methyl bromide poisoning.

A case of preventable fatality and a nearly greater disaster as a result of methyl bromide fumigation of a restaurant is presented. Methyl bromide is a nearly odorless, volatile hydrocarbon used as a fumigant in the food industry. As a result of this episode, recommendations are made for worker and community notification of the hazards involved whenever fumigation takes place. Addition of a mucosal irritant or olfactory stimulant is recommended to provide warning for methyl bromide exposure.

Fumigation↗
PubMed1993

Investigation of a fatality from nonoccupational aluminum phosphide exposure: measurement of aluminum in tissue and body fluids as a marker of exposure.

This case study reports our clinical and laboratory investigation of the accidental death of a pregnant rural woman related to phosphine exposure from stored grain fumigated with aluminum phosphide (AIP3) pellets. Environmental data (housing proximity to fumigated grain and meteorologic conditions at the time) coupled with clinical data (tachycardia and the rapid development of pulmonary edema with no antecedent clinical abnormalities) suggested possible toxicant effects. Gross and microscopic autopsy findings demonstrated pulmonary edema. Because phosphine generated from the phosphide is highly reactive and unstable, our laboratory strategy for this investigation focused on the quantitative analysis of aluminum (AI) in blood, gastric contents, and in lung tissue to test the possibility of fumigant intoxication. We recovered 713 ng/ml Al from blood (normal laboratory range 2 to 42 ng/ml). Laser mass spectral analysis of lung tissue demonstrated high concentrations of Al in alveolar macrophages (> 200 ppm) with little or no Al in adjacent lung tissue. Control lung tissue from an urban autopsy case matched by age, sex, and smoking habits showed no demonstrable Al. We conclude that Al may be a useful marker for AIP3 exposure.

Adult↗
PubMed2006

Effect of Cymbopogon citratus L. essential oil on growth and morphogenesis of Saccharomyces cerevisiae ML2-strain.

The growth of Saccharomyces cerevisiae was completely inhibited using 2.0 microl/ml or 4.0 microl/ml of Cymbopogon citratus essential oil applied by fumigation or contact method in Sabouraud's broth medium, respectively. This oil was found also to be fungicidal at the same concentrations. The sublethal doses 1.0 and 3.0 microl/ml inhibited about 98% of yeast growth after 24 hr of incubation as compared with the control. Microscopic observations using Light Microscope (LM), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) showed morphogenic and ultrastructure changes in the fumigated cells with 1.0 microl/ml of the oil. These changes including decrease in cell size, depressions on the surface of the cells, alteration in cell wall thickness and disruption of plasma membrane. Moreover, Ca(+2), K(+) and Mg(+2) leakages increased from the fumigated cells and its total lipid content decreased. Also, the fatty acid composition was altered with decrease in the amount of saturated fatty acids and increase in the amount of unsaturated fatty acids.

Antifungal Agents↗
PubMed2005

The potential efficiency of irrigation management and propargyl bromide in controlling three soil pests: Tylenchulus semipenetrans, Fusarium oxysporum and Echinochloa crus-galli.

Propargyl bromide (3-bromopropyne, 3BP) is a potential alternative for methyl bromide. Little information is available about its efficiency in controlling pests. The purpose of this paper is to estimate the 3BP dose required for killing three pests and to compare the efficiency of water management approaches to that of fumigation. The pests, Fusarium oxysporum Schlecht (fungus), Echinochloa crus-galli (L) Beauv (grass) and Tylenchulus semipenetrans Cobb (nematode) were exposed to different 3BP concentrations in a sandy loam at 30 degrees C in a closed system. The lethal dose for killing 90% of the population (LD90) was calculated from the total applied mass, and varied from 0.3 microg g(-1) soil for the nematode, 3 microg g(-1) for the grass, and 9 microg g(-1) for the fungus. The concentration-time index for killing 90% of the population (CT90) was 11 microg g(-1) h for the nematode, 112 microg g(-1) h for the grass and 345 microg g(-1) h for the fungus. 3BP seems as efficient as other fumigant alternatives in controlling these pests. Using an open system, it was shown that the volume of soil in which the pests were controlled varied for different irrigation managements. Even 96 h after fumigation (with a concentration 10 times higher than would potentially be applied in the field), more than 20% of the soil volume had not reached the fungus and grass CT90 of the non-irrigated soil. The soil underneath the furrow and the bed reached CT90 only slowly in all irrigated treatments even though techniques for increasing efficiency were used (tarping, surface sealing with water and high application rate).

Agriculture↗
PubMed2003

Evaluation of chemical and integrated strategies as alternatives to methyl bromide for the control of root-knot nematodes in Greece.

Current environmental awareness has led to a greater demand for alternative nematode control strategies. Three field experiments were established to compare management tactics on cucumber in commercial greenhouses naturally infested with root-knot nematodes (Meloidogyne spp). Cucumber rootstocks which have shown resistance to soil-borne diseases were tested to reveal any resistance/tolerance to root-knot nematodes, and integration of these rootstocks with nematicides was investigated. Metham-sodium and 1,3-dichloropropene (1,3-D) provided good control of nematode populations when their application was followed by the application of a non-fumigant nematicide such as cadusafos or oxamyl. Neither fumigant could provide season-long control of nematode populations, and a further application of cadusafos was required for satisfactory control. The efficacy of metham-sodium was significantly increased when injected into soil in comparison with its application through the drip irrigation system. The use of rootstocks resistant to soil-borne fungal pathogens used together with chemical means of nematode control provided promising results for their further use in integrated strategies as alternatives to methyl bromide. However, the latter was the superior treatment for the control of root-knot nematodes in soil infested with residues of galled roots. Dazomet, metham-sodium nor the non-fumigant nematicides oxamyl and fenamiphos could reduce nematode population as efficiently as methyl bromide. None of the chemicals tested except methyl bromide could enter galled roots and kill surviving nematodes.

Animals↗
PubMed1987

SO2-sensitivity of plant communities in a beech forest.

The ground vegetation of a beech forest was fumigated discontinuously for 4 h per week in transportable open-top chambers with 300 microg SO(2)m(-3), representing the SO(2) peaks in ambient air. This fumigation did not lead to visible injuries, but caused a decrease of productivity and leaf area indices for several of the species occurring. During the fumigation, transpiration and photosynthesis were depressed. The recovery time after the stress was shorter for those species with a lower susceptibility to SO(2).

Journal Article↗
PubMed1987

Screening loblolly pine seedling responses to SO2 and O3: analysis of families differing in resistance to fusiform rust disease.

Open pollinated families of loblolly pine differing in resistance to fusiform rust disease were screened in laboratory studies for responses to gaseous air pollutants. Twenty families were given acute exposures (2 fumigations for 4 h each) to SO(2) (0.4-1.0 ppm), O(3) (0.25 ppm), SO(2) (0.4-1.0 ppm) + O(3) (0.25 ppm) and control. Analyses of variance were performed to evaluate the treatment effects of these air pollutants on percent foliar injury, and to determine whether the families responded differentially to the air pollution treatments. Treatment effects were significant, with the combination treatment of SO(2) + O(3) producing a higher percentage of foliar injury than the controls; however, injury levels were very low and may not be of biological significance. Subsequently, twelve families were grown in two soil types for exposure to chronic levels of SO(2) (0.06 ppm), O(3) (0.07 ppm), SO(2) (0.06 ppm) + O(3) (0.07 ppm) and control. The families were then ranked for decreased primary shoot growth, shoot dry weight, root dry weight, total plant dry weight and root/shoot ratio after exposure to air pollution treatments. Air pollution treatments as a main effect were significant for only one of five growth parameters measured, that of primary shoot growth. The main effect of family, and the interaction of family and air pollution treatments, were significant for most growth parameters measured. In general, O(3) alone and in combination with SO(2) reduced growth more than SO(2) alone. Fumigation with O(3) reduced growth of two families in comparison with control groups, whereas SO(2) alone produced decreased growth in one family and stimulated growth in three families. Treatment with O(3) alone produced higher root/shoot ratios than fumigation with charcoal-filtered air in two families. Overall, families which were fast growers under control conditions maintained their ranking after exposure to air pollution. Families producing less growth in charcoal-filtered air also produced less growth under various air pollution regimes. Results indicated that these families exhibited a high degree of resistance to air pollution injury. Growth responses of seedlings may not reflect family differences in long-term productivity. No relationship was apparent between fusiform rust resistance and growth reductions due to air pollutants.

Journal Article↗
PubMed1990

The effects of sulphur dioxide on the parasitism of the rust fungus Uromyces viciae-fabae on Vicia faba.

Vicia faba cv. Aguadulce was grown in fumigation chambers ventilated with filtered air or air containing sulphur dioxide (SO(2)) at controlled concentrations, and inoculated with the rust fungus Uromyces viciae-fabae. The influence of the pollutant was rated in terms of production of uredia and dehiscent urediospores. Exposures to SO(2) levels around 70-90 nl litre(-1) enhanced uredia density. Pre-inoculation fumigations at 70-86 nl litre(-1) increased uredia density, whilst post-inoculation fumigations stimulated urediospore production. Lower concentrations increased diffusion resistance of the host plant and slightly increased uredia density. Concentrations between 100 and 130 nl litre(-1) were somewhat inhibitory for the parasite, even in the absence of any visible damage symptoms on the host. Total sulphur accumulation in leaf tissue was reduced by the presence of the fungal infection. Growing under SO(2) pollution neither decreased germination ability nor modified morphological parameters of the urediospores. However, elongation of the germination tube of spores coming from filtered air was adversely affected by the pollutant.

Journal Article↗
PubMed1990

CO2/H2O gas exchange parameters of one- and two-year-old needles of spruce and fir.

Gas exchange was characterized in one- and two year-old spruce (Picea abies L. Karst.) and fir seedlings (Abies alba Mill.) which had been exposed to low levels of ozone, sulfur dioxide and simulated rain or a combination of all three variables in open top chambers from 1983 through 1988. The gas exchange measurements were carried out in March 1988 at the end of the five year experiment. The twigs examined did not exhibit any visible sign of injury, specifically no differences were apparent between trees under the treatments of simulated acidic rain at pH 5.0 and pH 4.0. The study of carbon dioxide response curves showed different effects of the pollutants on the tree species. One-Year-old spruce needles treated with O(3) and simulated acidic precipitation pH 4.0 showed noticeable reduction of net photosynthetic rate. Exposure to the combination O(3) and SO(2) at pH 4.0 resulted in a significant depression of photosynthesis in two-year-old needles Transpiration rate was not decreased to a similar extent. No changes either in photosynthesis or transpiration were found in spruce under fumigation with SO(2) alone. These results indicate that ozone is the principal cause of changes in photosynthetic performance of spruce. It alters mesophyll response rather than reducing stomatal conductance. The specific changes that occur in the mesophyll could be diagnosed as inactivation of a carbon fixing enzyme as well as damage of the electron transport system. Fir seem to be more tolerant to ozone. No changes in photosynthesis and transpiration following exposure to O(3) alone were found. However, SO(2) fumigation, alone or in combination with O(3), resulted in a marked decrease of photosynthetic performance. Particularly, carboxylation efficiency and also maximum carboxylation velocity were depressed indicating a reduction in carbon fixing enzyme activity. No differences between single and combined fumigation treatments regarding these variables were determined. However, parameters measured to determine changes in electron transport rate showed a higher depression in the presence of both pollutants. Transpiration also was reduced by SO(2).

Journal Article↗
PubMed1992

Effects of atmospheric ammonia and ammonium sulphate on Douglas fir (Pseudotsuga menziesii).

Three-year-old Douglas firs (Pseudotsuga menziesii) were fumigated with 180 microg m(-3) NH3 or clean (charcoal-filtered) air. During these fumigations the plants received 15 mm artificial rain weekly, supplemented with 20, 500 or 2500 micromol litre(-1) (NH4)2SO4. Exposure to NH3 and NH4+ for 14 weeks resulted in a change of the nutrient status of the needles. The most remarkable effect was the increase in the N/K ratio, due to both uptake of N and leaching of K. The action of NH3 was stronger than that of NH4+. Both NH3 and (NH4)2SO4 affected the epicuticular wax layer and decreased mycorhiza frequency. Following fumigation and artificial rain treatments, needles were incubated for 8 h in a medium containing 0, 50, 250, 500 and 2500 micromol litre(-1) (NH4)2SO4. Almost no exchange of Ca, Mg and K for NH4+ was found. Therefore this ion exchange probably explains only a minor part of the changes in nutrient status of the whole trees.

Journal Article↗
PubMed1992

Tolerance to SO2, NO2 and their mixture in Plantago major L. populations.

The possible evolution of tolerance to NO2, alone or in combination with SO2 was investigated in three populations of Plantago major L., originating from Hyde Park in central London (polluted site), Ascot (clean site) and The Netherlands. Screening for sensitivity to the pollutants was carried out by means of chronic fumigations with NO2 or NO2 plus SO2 and acute fumigations with SO2, NO2 or their mixture. The Hyde Park population showed smaller growth reductions induced by the pollutant mixture, than did the other populations. In contrast no differential response in terms of foliar injury was observed after an acute fumigation with SO2+ NO2, but the Hyde Park population was the most sensitive to NO2 alone. The results indicate that selection for tolerance to SO2 does not confer tolerance to NO2 alone or the pollutant mixture.

Journal Article↗