Technical Grade Material Research Articles

Bioconcentration and depuration of endosulfan sulfate in mosquito fish ( Gambusia affinis)

Endosulfan is an insecticide which has been widely used in agriculture. The technical grade material consists of two isomers (alpha and beta). Under natural environmental conditions, endosulfan is metabolized through oxidation and the main metabolite in the environment is endosulfan sulfate. Most ecotoxicology research has been conducted with technical grade endosulfan to determine effects on non-target aquatic organisms. Little data on the effects of endosulfan sulfate on aquatic organisms are available in the literature. This study characterizes endosulfan sulfate bioconcentration and depuration in mosquito fish ( Gambusia affinis). During the study, G. affinis was exposed to an environmentally relevant endosulfan sulfate concentration of 0.25 μg L −1 for 5 weeks (uptake phase) followed by a 3-week period (depuration phase) in clean water. This study found that G. affinis bioconcentrated endosulfan sulfate. During the exposure phase, fish tissue concentrations of endosulfan sulfate increased with time up to 730 μg kg −1 dw or 215 μg kg −1 ww. The bioconcentration data followed Michaelis–Menten kinetics better than the one-compartment first order kinetics (1-CFOK). Using these models, the bioconcentration factors for endosulfan sulfate-exposed G. affinis were from 687 to 888 L kg −1 in wet weight or 2263 to 2936 L kg −1 in dry weight. During the depuration phase, endosulfan sulfate concentrations in tissue significantly decreased and the data followed first order kinetics. The half-life of endosulfan sulfate in G. affinis was about 9 d. There was no significant difference in standard length or weight between control and exposed fish. The growth data followed the von Bertalanffy growth model. However, the condition factor of exposed fish increased with time during the exposure phase.

Heterogeneous oxidation of the insecticide cypermethrin as thin film and airborne particles by hydroxyl radicals and ozone

Evaluation of pesticides' fate in the atmosphere is important in terms of environmental effects on non-target areas and risk assessments analysis. This evaluation is usually done in the laboratory using analytical grade materials and is then extrapolated to more realistic conditions. To assess the effect of the pesticide purity level (i.e. analytical vs. technical) and state (i.e. sorbed film vs. airborne particles), we have investigated the oxidation rates and products of technical grade cypermethrin as thin film and in its airborne form, and compared it with our former results for analytical grade material. Technical grade thin film kinetics for both ozone and OH radicals revealed reaction rates similar to the analytical material, implying that for these processes, the analytical grade can be used as a good proxy. Oxidation products, however, were slightly different with two additional condensed phase products: formanilide, N-phenyl and 2-biphenyl carboxylic acid, which were seen with the technical grade material only. OH experiments revealed spectral changes that suggest the immediate formation of surface products containing OH functionalities. For the ozonolysis studies of airborne material, a novel set-up was used, which included a long-path FTIR cell in conjugation with a Scanning Mobility Particle Sizer (SMPS) system. This set-up allowed monitoring of real-time reaction kinetics and product formation (gas and condensed phases) together with aerosol size distribution measurements. Similar condensed phase products were observed for airborne and thin film technical grade cypermethrin after ozonolysis. Additionally, CO, CO(2) and possibly acetaldehyde were identified as gaseous oxidation products in the aerosols experiments only. A kinetic model fitted to our experimental system enabled the identification of both primary and secondary products as well as extraction of a formation rate constant. Kinetic calculations (based on gaseous products formation rate) have revealed values similar to that of the thin film experiments. Interestingly, heterogeneous oxidation of cypermethrin was also found to generate ultra fine secondary organic aerosols. Again, no significant difference was observed between analytical and technical grade materials. However, particle size distribution was much broader when films were exposed to OH and ozone than to ozone alone.

Chiral Liquid Chromatography−Circular Dichroism−NMR for Estimating Separation Conditions of Chiral HPLC without Authentic Samples

Chiral separation by high performance liquid chromatography (Chiral HPLC) is one of the most powerful methods for estimating optical and chemical purity of chiral compounds. However, it has a weakness in that much time and effort are required to prepare authentic samples. A novel chiral liquid chromatography-circular dichroism-NMR (LC-CD-NMR) technique, on the other hand, requires only crude chiral compounds that include enantiomers as minor impurities. In this study, chiral LC-CD-NMR was constructed by connecting a conventional LC-NMR system with a CD detector. A pyridylalanine derivative mixture was prepared to mimic technical grade material in an early phase of development. By chiral LC-CD-NMR, the enantiomer peak is identified by an opposite sign of the CD Cotton effect curve and an identical (1)H NMR spectrum to that of the main component. Using NMR as a detector, this method is superior in ability to discriminate enantiomers from other isomers indistinguishable by MS. Furthermore, this method is also applicable for selecting the best separation conditions of chiral HPLC. The degrees of separation (Rs) between the main component and its enantiomer in several chiral columns were compared. Even with modern chromatographic methods, establishing the best chiral HPLC conditions in an early phase of development is difficult: chiral LC-CD-NMR is a suitable solution.

Endosulfan and its metabolite, endosulfan sulfate, in freshwater ecosystems of South Florida: a probabilistic aquatic ecological risk assessment

Endosulfan is an insecticide-acaricide used in South Florida and is one of the remaining organochlorine insecticides registered under the Federal Insecticide Fungicide and Rodenticide Act by the U.S.EPA. The technical grade material consists of two isomers (alpha-, beta-) and the main environmental metabolite in water, sediment and tissue is endosulfan sulfate through oxidation. A comprehensive probabilistic aquatic ecological risk assessment was conducted to determine the potential risks of existing exposures to endosulfan and endosulfan sulfate in freshwaters of South Florida based on historical data (1992-2007). The assessment included hazard assessment (Tier 1) followed by probabilistic risk assessment (Tier 2). Tier 1 compared actual measured concentrations in surface freshwaters of 47 sites in South Florida from historical data to U.S.EPA numerical water quality criteria. Based on results of Tier 1, Tier 2 focused on the acute and chronic risks of endosulfan at nine sites by comparing distributions of surface water exposure concentrations of endosulfan [i.e., for total endosulfan (summation of concentrations of alpha- and beta-isomers plus the sulfate), alpha- plus beta-endosulfan, and endosulfan sulfate (alone)] with distributions of species effects from laboratory toxicity data. In Tier 2 the distribution of total endosulfan in fish tissue (whole body) from South Florida freshwaters was also used to determine the probability of exceeding a distribution of whole body residues of endosulfan producing mortality (critical lethal residues). Tier 1 showed the majority of endosulfan water quality violations in South Florida were at locations S-178 followed by S-177 in the C-111 system (southeastern boundary of Everglades National Park (ENP)). Nine surface water sampling sites were chosen for Tier 2. Tier 2 showed the highest potentially affected fraction of toxicity values (>10%) by the estimated 90th centile exposure concentration (total endosulfan) was at S-178. At all other freshwater sites there were <5% of the toxicity values exceeded. Potential chronic risk (9.2% for total endosulfan) was only found at S-178 and all other sites were <5%. Joint probability curves showed the higher probability of risk at S-178 than at S-177. The freshwater fish species which contain tissue concentrations of endosulfan (total) with the highest potential risk for lethal whole body tissue residues were marsh killifish, flagfish and mosquitofish. Based on existing surface water exposures and available aquatic toxicity data, there are potential risks of total endosulfan to freshwater organisms in South Florida. Although there are uncertainties, the presence of tissue concentrations of endosulfan in small demersal fish, is of ecological significance since these fish support higher trophic level species, such as wading birds.

Evaluation of the benefits of an insecticide resistance management programme in Punjab in India

In India, many IPM programmes have been implemented, but they have not achieved the desired level of success in reducing insecticide use and increasing adoption of IPM practices. This inter-disciplinary study evaluated an Insecticide Resistance Management-based Integrated Pest Management (IRM-IPM) programme in cotton and compared it with non-IRM production for a range of IPM and economic measures. The IRM-IPM programme has been implemented in 28 districts of 10 states of India since 2002 to help rationalize and reduce the use of insecticides and to overcome the development of resistance in cotton pests, especially Helicoverpa armigera. The IRM-IPM strategy includes applying insecticides only when pests exceed economic threshold levels, using selective insecticides that are compatible with biological control, and rotating between different insecticide classes. The IRM-IPM programme we evaluated resulted in a reduction in insecticide consumption (technical grade material) by 30%, and it reduced the number of sprays by 15%; however, it did not result in a significant change in productivity. The majority of IRM farmers avoided using highly toxic insecticides such as monocrotophos, avoided use of synthetic pyrethroids beyond 140 days after sowing to avoid resurgence of Bemisia tabaci, and rotated the insecticide compounds/groups to delay the development of resistance and ensured effective management of H. armigera. On average, the IRM-IPM programme resulted in a return of US $24.05 ha−1 (at 2005 rates: US $1 = 45 Indian rupees), by saving on insecticide costs. While the farmers gained significantly in knowledge of IPM practices, the level of adoption of IPM techniques was low. Further studies based on impact evaluation methodology, employing a with/without and before/after quasi-experimental design, would provide feedback to help in the formulation of future IPM strategies.

Mobility of isoproturon from an alginate–bentonite controlled release formulation in layered soil

The mobility of isoproturon [3-(4-isopropylphenyl)-1,1-dimethylurea] from an alginate-based controlled release (CR) formulation was investigated by using soil columns. A layered bed system simulating the typical arrangement under a plastic greenhouse, which is composed of sand, peat, amended soil and native soil was used. The CR formulation was based on sodium alginate (1.87%), isoproturon (1.19%), natural bentonite (3.28%), and water (93.66%), and was compared to technical grade isoproturon. The use of the alginate–bentonite CR formulation produced less vertical mobility of the active ingredient as compared to the technical product. There was no presence of herbicide in the leachate when the alginate–bentonite CR formulation was used. However, 0.90% of isoproturon appeared when the treatment was carried out with technical grade material. Isoproturon mobility was modelled using the programme CMLS, which showed the peat layer to retard pesticide leaching. Analysis of the soil columns showed the highest isoproturon concentration in the peat layer.

Mobility of imidacloprid from alginate-bentonite controlled-release formulations in greenhouse soils

The mobility of imidacloprid [1-(6-chloro-3-pyridinyl)methyl]-N-nitro-2-imidazolidinimine] from alginate-based controlled-release (CR) formulations was investigated in two different soil profiles. In one, a layered bed system simulating the typical arrangement under a plastic greenhouse, which is composed of sand, peat, amended soil and native soil, was used. In the other, the layer containing amended soil was used in order to determine the mobility of the insecticide in a soil system with a low content of organic matter and a high content of clay. Two CR formulations based on sodium alginate (1.87% wt/wt), imidacloprid (1.21%), natural or acid-treated bentonite (3.28%), and water (93.64%) were compared to technical grade imidacloprid. The use of alginate CR formulations produced less vertical mobility of the active ingredient as compared to the technical product. With the technical grade product treatment, the total amount of imidacloprid leached from columns packed with amended soil was 82.3% of that applied, whereas for the alginate-based CR formulations containing natural or acid-treated bentonite, the leached percentages were 44.7% and 37.1%, respectively. In the column experiments simulating the layered bed system, no insecticide was found in the leachate when the alginate-based CR formulations containing natural bentonite were used. However, 3% of the applied imidacloprid appeared when the treatment was carried out with technical grade material. Sorption-desorption capacities of the various soil layers for imidacloprid molecules were also calculated using batch experiments. © 1999 Society of Chemical Industry

The commercial use of azadirachtin and its integration into viable pest control programmes

With the continued robust growth of the global biopesticide market, azadirachtin is uniquely positioned to become a key insecticide to expand in this market segment. In the USA the actual or impending cancellation of some organophosphate and carbamate insecticides that have either lost patent protection or are not being re-registered in many markets because of the Food Quality Protection Act of 1996, has opened new opportunities for biopesticides and reduced-risk pesticides in general. The broad-spectrum activity of azadirachtin at low use rates (12·5 to 40 g AI ha-1) coupled with the insect growth regulator activity (in all larval/nymphal instars including the pupal stage) and unique mode of action (ecdysone disruptor), make azadirachtin an ideal candidate for insecticide resistance, integrated pest control and organic pest control programmes. Azadirachtin has been exempted from residue tolerance requirements by the US Environmental Protection Agency for food crop applications. Azadirachtin exhibits good efficacy against key pests such as whiteflies, leafminers, fungus gnats, thrips, aphids and many leaf-eating caterpillars. Azadirachtin has minimal to no impact on non-target organisms, is compatible with other biological control agents and has a good fit into classical Integrated Pest Management programmes. The world's largest azadirachtin extraction facility has been fully commissioned in India to process over 10,000 tonnes neem seeds per annum. This will ensure the wide availability of azadirachtin technical grade material in the future. © 1998 Society of Chemical Industry.

Reducing Superficial Scald of Apples and Pear with Naturally Occurring Triterpenoid Compounds

Superficial scald is a physiological skin disorder of apples and pears that develops in cold storage and that often increases in severity after the fruit is removed. It is thought to be associated with the accumulation of farnesene in the epithelial tissue. Currently used methods of controlling scald are diphenylamine (DPA) drenches, and controlled atmosphere (CA) to a limited extent. In order to expand the methods available to control scald, we have been investigating the potential of a number of naturally occurring compounds applied to the fruit surface by drenching or by topical application. Fruit were treated either by wiping the fruit surface with technical-grade material and then removing the excess, drenching whole fruit in aqueous emulsions, or drenching fruit in combinations of heat plus emulsion. After treatment, the fruit was air-dried for 30 min and then placed either in regular or CA storage for 6 months, after which time they were placed in a dark room at 68F for 7 days. Scald was evaluated and fruit condition assessed. Results from 3 years indicate farnesene and squalene reduce scald in apples and pears.

Absorption, Metabolism, and Excretion of N,N-Diethyl- m-toluamide Following Dermal Application to Human Volunteers

Absorption, Metabolism, and Excretion of N,N -Diethyl- m-toluamide Following Dermal Application to Human Volunteers. Selim, S., Hartnagel, R. E., Jr., Osimitz, T. G., Gabriel, K. L., and Schoenig, G. P. (1995). Fundam. Appl. Toxicol. 25, 95-100. The absorption, metabolism, and excretion of N,N -diethyl- m-toluamide (DEET) in male human volunteers following dermal application of [ 14C]DEET was studied. DEET was applied to two groups of six volunteers either as the undiluted technical grade material or as a 15% solution in ethanol. The material was applied over a 4 × 6-cm area on the volar surface of the forearm and was left in contact with the skin for 8 hr, then rinsed off the skin. Application sites also were tape stripped at 1, 23, and 45 hr after rinsing. Serial blood samples and all urine and feces were collected for 5 days after application. Aliquots of these materials were analyzed for total radioactivity in order to define absorption and excretion patterns, Urine samples also were analyzed by HPLC to characterize the metabolic profile and/or to identify metabolites. Absorption of DEET as evidenced by plasma radioactivity occurred within 2 hr after dose application. Elimination of radioactivity from plasma was rapid and quantifiable levels of radioactivity were observed in plasma for only 4 hr after the end of the 8-hr exposure period. Urine was the principal route of excretion of radioactivity and accounted for an average of 5.61 and 8.33% of the applied dose in the undiluted DEET and 15% DEET in ethanol groups, respectively. Excretion of radioactivity in the feces was less than 0.08% of the applied dose in both groups. DEET did not accumulate in the superficial layers of the skin as evidenced by low amounts of radioactivity in the tape strippings. The major fraction of the applied radioactivity was recovered in the skin rinses. Absorbed DEET was completely metabolized and six major metabolites were observed in urine. Two major urinary metabolites tentatively were identified. Based upon the percentage of applied dose recovered in the excreta, dermal absorption of DEET ranged from 3 to 8% with a mean of 5.6% in the volunteers applied undiluted technical grade DEET. The corresponding values for the volunteers applied 15% DEET in ethanol were 4 to 14% and 8.4%, respectively.

Sevin Versus Cyfluthrin in Cucurbit Bait for Western Corn Rootworm Beetles

Abstract Four-day old, laboratoryreared male WCR beetles were assayed under clear plastic cones (11.5 cm diam., 9 cm ht.) placed on black poster board and set upon a laboratory countertop. Ten WCR were added per cone. WCR were fed until about 1 h before the bioassay. The narrow end of a no. 8 cork was fitted about 0.5 cm into an opening (2 cm diam.) at the top of the cone. This end was bored (1 cm depth, 1.3 cm diam.), and the bore was filled with 1.5 g of toxic bait. Bait contained 2% (wt.) carbaryl, 0.024% cyfluthrin, 0.12% cyfluthrin, or no insecticide. Carbaryl was a 40% AI (wt.) formulation of Sevin XLR, and cyfluthrin was a 93% pure technical grade material. Each bait contained 5% powdered root of buffalo gourd (Cucurbita foetidissima H.B.K.), which acted as a feeding stimulant. The remainder of the bait was composed of a 3:1 (w/w) mixture of artificial patty diet and corn oil. Treatments were arranged in a randomized complete block design with 5 replications. Moribund beetles were counted at 30 min and 1 h.

Comparison of short-term aquatic toxicity: Formulation vs active ingredients of pesticides

EC50 values for algae and water fleas and LC50 values for fish of formulated pesticide products from standardized short term toxicity tests have been compared with the corresponding values of the respective active ingredients (AI). The results suggest that toxicity tests conducted with the technical material will provide adequate information for estimating toxicological hazard of formulations to aquatic organisms. A preliminary hazard assessment performed by using the toxicity of the technical grade material divided by a species and formulation related factor of extrapolation uncertainty would allow a hazard assessment for the formulation with a high degree of reliability. Based on the presented data, this factor could be as low as 5 for green algae, 10 for water fleas, and 5 for fish without an unreasonable risk (2% or less) of substantially increased, environmentally relevant formulation toxicity. Such an approach would save considerable numbers of test animals and also allow improvement of formulations without unnecessary or even economically prohibitive replications of numerous tests.

An Overview of the Pesticides Industry and its Marketing Environment

The pesticides industry has grown by 7.6 per cent during the last 20 years. It has also undergone a structural change from low value products to high value products. The major constituents of this industry are technical grade material manufacturers, formulators, and dealers. In this article, U K Srivastava and N T Patel analyse the growth of the pesticides industry, the changes in the product mix, the problems of the constituents, and the marketing scenario. According to them, there is vast scope for accelerating pesticides consumption by diversifying to hitherto untapped regions and crops. This, however, calls for a major market development effort on the part of the industry.

A comparative analysis of the acute toxicity of technical-grade pyrethroid insecticides and their commercial formulations

Seventy-two-hour LD 50 studies involving the fenvalerate formulation, Pydrin 2.4 E.C., and the permethrin formulation, Ambush, were performed with male Swiss mice to compare the toxicity of the commercial formulations to that of the technical-grade pyrethroids. Comparison of the formulation ip and po LD 50 values and the lethality of technical-grade pyrethroids revealed an increased toxicity of the technical-grade material when administered as the commercially formulated products. The calculated ip and po LD 50 values for Pydrin 2.4 E.C. and Ambush were calculated to be 62 and 72 mg/kg, respectively, whereas those for Ambush were 429 and 424 mg/kg. Administration of doses of technical-grade fenvalerate which corresponded to the amount of fenvalerate contained in the calculated LD 99 value of Pydrin resulted in no deaths. Administration of the LD 99 value of Ambush, as the technical-grade product, resulted in no deaths following ip administration, whereas the po value resulted in 100% death. The data indicate an effect of the Pydrin formulation vehicle on fenvalerate toxicity, whereas the Ambush vehicle did not enhance permethrin toxicity. Technical-grade material in general was more toxic following po than ip administration suggesting the corn oil vehicle may have reduced ip absorption.

Acute toxicity of selected herbicides and surfactants to larvae of the midgeChironomus riparius

The acute toxicities of eight commercial herbicides and two surfactants to early fourth instar larvae of the midgeChironomus riparius were determined under static conditions. The formulated herbicides tested were Eradicane® (EPTC), Fargo® (triallate), Lasso® (alachlor), ME4 Brominal® (bromoxynil), Ramrod® (propachlor), Rodeo® (glyphosate), Sencor® (metribuzin), and Sutan (+)® (butylate); the two surfactants were Activator N.F.® and Ortho X-77®. In addition, technical grade alachlor, metribuzin, propachlor, and triallate were tested for comparison with the formulated herbicides. The relative toxicity of the commercial formulations, based on percent active ingredient, varied considerably. The EC50 values ranged from 1.23 mg/L for Fargo® to 5,600 mg/L for Rodeo®. Fargo®, ME4 Brominal®, and Ramrod® were moderately toxic to midge larvae; Lasso®, Sutan (+)®, and Eradicane® were slightly toxic; and Sencor® and Rodeo® were practically non-toxic. The 48-hr EC50 values of the two surfactants were nearly identical and were considered moderately toxic to midges. For two of the herbicides in which the technical grade material was tested, the inert ingredients in the formulations had a significant effect on the toxicity of the active ingredients. Fargo® was twice as toxic as technical grade triallate, whereas Sencor® was considerably less toxic than technical grade metribuzin. A comparison of the slope function values indicated that the toxic action of all the compounds occurred within a relatively narrow range. Published acute toxicity data on these compounds for other freshwater biota were tabulated and compared with our results. In general, the relative order of toxicity toC. riparius was similar to those for other freshwater invertebrates and fish. Maximum concentrations of each herbicide in bulk runoff during a projected “critical” runoff event were calculated as a percentage of the application rate lost in a given volume of runoff. A comparison between estimated maximum herbicide concentrations in runoff and results of acute tests indicated that Ramrod®, ME4 Brominal®, and Lasso® pose the greatest direct risk to midge larvae during a storm event.

Determination of drug protein-binding by high-performance liquid chromatography using a chemically bonded bovine albumin stationary phase.

A liquid chromatographic method for the determination of the degree of protein-binding of drugs has been established, using a stationary phase to which bovine serum albumin has been bonded chemically. In a structurally heterogeneous group of compounds, results of the method correlate well with protein-binding data obtained by equilibrium dialysis (r = 0.89, n = 23, p less than 0.001). Within a series of analogous piperazines a good correlation is found (r = 0.981, n = 11, p less than 0.001). The chromatographic method allows automation of the measurement of protein-binding of large series of compounds with protein-binding ranging between 10 and 99%. The method is not expensive and is less time consuming than equilibrium dialysis. Only 1 mg of technical-grade material is required to determine the protein-binding, and radioactive labelling of the material is not necessary.

Health and environmental effects profile for pentachloronitrobenzene.

Pure pentachloronitrobenzene (PCNB) is a colorless crystalline solid (Worthing, 1983). The commercial product may have a light-yellow to cream color with a musty odor (Hartley and Kidd, 1983). It is practically insoluble in a number of organic solvents. The compound is reasonably stable but may undergo hydrolysis in a strong alkaline medium (Hartley and Kidd, 1983). In 1983, Olin Corp., Leland, MS, was the only manufacturer of PCNB in the United States (SRI, 1984; Hartley and Kidd, 1983). No data for U.S. production volume for this chemical are available, but recent production source data (USITC, 1985; SRI, 1985) suggest that this chemical is no longer commercially produced in the United States. The primary usage of PCNB is as a soil fungicide for a wide variety of crops and in seed treatment (Worthing, 1983; Hartley and Kidd, 1983). The fate of PCNB in water has not been comprehensively studied. Only qualitative data regarding fate and transport in water are available. The half-life of PCNB in the water phase was estimated to be 1.8 days. The two processes reported to be most responsible for the rapid decrease in PCNB concentration in water were volatilization and sorption to seston and biota, followed by sedimentation as detritus (Schauerte et al., 1982). Neither biodegradation nor photolysis appears to be a significant process for the loss of PCNB from water (Crosby and Hamadmad, 1971; Schauerte et al., 1982). The BCFs for PCNB in the golden orfe, Leucisens idus melanotus, and in rainbow trout, Salmo gairdneri, were reported to be 950-1130 and 260-590, respectively (Korte et al., 1978; Oliver and Niimi, 1985). It therefore appears that PCNB will moderately bioaccumulate in aquatic organisms. Pertinent data regarding the fate and transport of PCNB in air could not be located in the available literature as cited in the Appendix. Based on its physical properties and its behavior in other media, it would appear that PCNB will persist in the atmosphere because no known chemical/photochemical processes significantly degrade this chemical. Precipitation of particulate PCNB, especially of larger particle size and higher particle density, may remove some PCNB from the atmosphere. PCNB is persistent in soils. The two processes that are important in the loss of PCNB from soils are volatilization and biodegradation; biodegradation is more rapid in soils under anaerobic conditions than under aerobic conditions (Ko and Farley, 1969; Casley, 1968; Gile and Gillett, 1979; Cole and Metcalf, 1977).(ABSTRACT TRUNCATED AT 400 WORDS)

Metabolism of 2,4-dinitrotoluene by intestinal microorganisms from rat, mouse, and man

Dinitrotoluene (DNT) is an industrial chemical of importance in the production of urethane foams and elastomers. The technical grade material is a hepatocarcinogen in rodents but shows sex- and species-dependent differences in potency. We have studied the pathways of metabolism of 2,4-dinitrotoluene (2,4-DNT), the major component of technical material, in the cecal microflora of male rats, female rats, male mice, and in human feces and ileal contents. 2,4-DNT was not metabolized by any of these preparations in the presence of oxygen. Under anaerobic conditions an ordered sequence of reductive metabolism was observed. The 2- and 4-nitro groups were reduced to amino groups via nitroso intermediates which were identified by GC-MS. The reduction of the nitroso intermediate to the amino compound is presumed to involve a hydroxylamino intermediate which could not be isolated. The aminonitro compounds were then reduced to diaminotoluene. No intermediates in this sequence could be isolated. No sex- or species-dependent differences in the pathways of metabolism were observed and only small species-dependent differences in the rate of metabolism of 2,4-DNT were observed. It is concluded that the intestinal microflora of rodents represent the major site of reductive metabolism of 2,4-DNT and may play an important role in the carcinogenic action of DNT isomers.

Metabolism of 2,4-dinitrotoluene by rat hepatic microsomes and cecal flora.

Dinitrotoluene (DNT) is an industrial chemical used as an intermediate in the production of toluene diisocyanate for the manufacture of polyurethane foams, coatings and elastomers. Technical grade DNT is a potent hepatocarcinogen which produces a dose related incidence of hepatocellular carcinoma in Fischer 344 rats (CIIT, 1979). The technical grade material comprises approximately 75% 2,4-DNT, 19.5% 2,6-DNT and 4% other DNT isomers with small amounts of mono-and tri-nitrotoluenes and nitrocresols also present. The major component of the technical grade material, 2,4-DNT, has also been demonstrated to be a hepatocarcinogen in CD-1 rats (Ellis et al., 1979).KeywordsHepatic MicrosomeAnaerobic IncubationMixed Function OxidaseCecal ContentNitro TolueneThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Candidate Pesticide Formulations for Quarantine Use, 1981

Abstract Two series of bioassay tests were conducted by exposing a total of 7; pest species in commercial transport trailers with volumes of 33 to 71 m . In the first series of tests, conducted in Miami, Florida, 5 species of colony-reared insects and 1 species of ticks were exposed. Approximately 100 resistant (Gainesville, multiple resistant) M. domestica, 50 resistant (Hazard) B. qermanica, 20 H. virescens, 50 A. grandis, and 50 R.sanquineus adults were, excepting A. taeniorhynchus (tested without replication), included in each of 3 test replications. In test series 2, conducted in Baltimore, Maryland, approximately 30 hazard strain B. germanica, 12 B. orientalis (males only) and 100 P. japonica were used in each test replication. Japanese beetles were field collected in methyl eugenol baited traps and caged in 83 mm diara x 60 mm deep, 3 mm mesh wire screen cages; all other species were caged in 0.24 L (1/2 pint - same dimensions as Japanese beetle cage) paper cans with tops replaced with tulle, nylon mesh screen (7 mesh/mm2). Candidate compounds were formulated as aerosols and dusts. Aerosols were formulated with technical grade material in a 1:1 mixture of Freons 11 and 12. The standard material for aerosol treatments, Sumithrin, was also formulated in an aqueous, CO^-propelled system by Enviro-Spray Systems, Inc. Dusts were formulated with HiSii 233 as the carrier. Sumithrin was also formulated with diatomaceous earth (Diabrite K-8, from international Diatoms Industries, Ltd). Cages were placed on the floor of the test trailer ca 10 cam from side walls. Dusts were applied with a “gun” employing compressed CO2 as the propellant, through the rear trailer door. Aerosols were applied from within by an operator walking the length of the trailer while releasing formulation for slightly less than the calculated time to obtain desired dosage and then weighing and adjusting with additional material. Following treatment, trailers were closed for 10 minutes. Then the right rear door was opened and test insects removed 20 min later. Japanese beetles were held for 72 hr before mortality counts were made; all others were counted at 24 hr after treatment. Average temperature during treatment and holding of the first test series was 21°C, and relative humidity was 81 ± 13%. In the second series temperatures averaged 23°C and relative humidity was 72%. Abbott’s formula was used to adjust for control mortality.