1‐Aminobenzotriazole increases glutathione‐s‐transferase activity of maize

Abstract

Glutathione‐S‐transferase (GST) activity of maize (Zea mays L.) seedlings treated with 1‐aminobenzotriazole (ABT) derivatives and/or EPTC were measured using EPTC‐sulfoxide as substrate. Both safeners and ABT derivatives significantly elevated the GST activity in the concentrations needed for effective safening action. ABT is considered as an inhibitor of plant cytochrome P‐450 monooxygenases (P‐450) and, because of this, used to study herbicide mode of action. Our data indicate that ABT has multiple effects on plants influencing not only P‐450 but GST as well. Thus the role of ABT in herbicide metabolism needs reconsideration.     

A new synthesis of tetrachlorofluorodibenzo‐p‐dioxin

Abstract

The 1,2,3,4‐tetrachloro‐7‐fluorodibenzo‐p‐dioxin has been synthesized via condensation of 4‐fluorocatechol and pentachloronitrobenzene. This compound could be used as an internal standard for the analysis of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin by Chromatographic methods.     

Metabolism of 14C‐carbaryl and 14C‐1‐naphthol in moist and flooded soils

Abstract

The metabolism of ¹⁴C‐carbaryl and ¹⁴C‐1‐naphthol in moist and flooded soils was studied in a continuous flow‐through system over a period of 28 days permitting ¹⁴C‐mass balance. The percent distribution of radiocarbon in organic volatiles, carbon dioxide, extractable and non‐extractable (bound) fractions of soils were determined. Organic volatiles could not be detected in both carbaryl and 1‐naphthol treated soils. More of ¹⁴CO₂ (25.6%) was evolved from moist than flooded soil (15.1%) treated with carbaryl. However, the mineralization of ¹⁴C‐1‐naphthol was negligible. The extractable radiocarbon was more in flooded soil (28.9%) than moist soil (5.5%) from carbaryl treatment. Less than one percent was present as parent compound, whereas carbaryl was mainly metabolized to 5‐hydroxy carbaryl in moist soil and to 4‐ and 5‐hydroxy carbaryl in flooded soil. The extractable radiocarbon amounted to 18.2 and 24.3% in moist and flooded soils respectively and the parent compound was less than one percent with 1‐naphthol treatment. Most of the radiocarbon was found as soil bound residues; the formation being more with 1‐naphthol than carbaryl. Humin fraction of the soil organic matter contributed most to soil bound residues of both carbaryl and 1‐naphthol.     

N1‐aryl‐N2‐dichloroacetyl glycine and alanineamides as selective safeners for corn against chloroacetanilide herbicides

Abstract

Structurally new N¹aryl‐N²‐dichloroacetyl glycine and alaninamides were prepared. Greenhouse experiments were conducted to determine the effectiveness of the new compounds in protecting corn seedlings from chloroacetanilide (acetochlor, alachlor, dimethachlor, metazachlor, metolachlor) injury using dichlormid and BASF‐145138 as standard safeners. High rates of chloroacetanilides caused significant injury to sensitive corn hybrids. The most acive derivatives reduced injury to corn from dimethachlor and metolachlor and lesser extent from acetochlor and metazachlor. The most effective derivatives of the new compounds displayed better safening activity than the standards. Some of the new compounds were found to be selective safeners when formulated as a tank mixture with metolachlor in a 1:33–100 safener‐to‐herbicide ratio showing the same or better activity than the standard used.

Nomenclature: BASF‐145138, 1‐dichloroacetyl‐hexahydro‐3,3,8α‐trimethyl‐pyrrolo‐[1,2‐α]—pyrimidin‐6‐(2H)‐one; EPTC, S‐ethyl‐N,N‐dipropylcarbamothioate; dichlormid, 2,2‐dichloro‐N,N‐di‐2‐propenyl acetamide; corn, Zea Mays L. ‘Pannonia SC’.     

Dissipation of chlorpyrifos,oxon, and 3,5,6‐trichloro‐2‐pyridinol in litter and elm forest soil

Abstract

After chlorpyrifos was applied to the basal 1 meter of elm tree trunks for control of elm bark beetles at two different application times and sites, initial chlorpyrifos residues in forest floor litter ranged from 120 to 916 μg/g depending on the application time. Residues dissipated by approximately 99% after 791 d with the DT₅₀ from 3.9 to 59 d and DT₉₀ from 55 to 310 d. The initial residues of chlorpyrifos in elm forest soil varied from 0.8 to 28 μg/g and were 1 to 2 μg/g at 791 d after application. The dissipation half‐lives of chlorpyrifos in fortified soil placed in the field ranged from 116 to 121 d.     

Chemical and biological release of 14C‐bound residues from soil treated with 14C‐p,p'‐DDT

Abstract

¹⁴C‐p,p'‐DDT‐bound residues in soil can be released by treatment with concentrated sulphuric acid at ambient temperatures. Within 6 days, about 70% of the bound residues was released. Bound residues released after 9 months incubation with ¹⁴C‐DDT showed the presence of DDT and DDE only while bound residues released after 18 months, contained in addition 13% DDD.

Release of bound ¹⁴C‐residues also occurs readily following inoculation of the soil‐bound residues with fresh soil or with individual microorganisms. Almost complete release of bound residues was observed after incubation for 45 days. The rate of release was rapid during the first two weeks and decreased thereafter. TLC and HPLC analysis showed that the released residues contained DDE (about 80%) and a smaller amount of DDD. The disappearance of DDT from the released residues may be attributed to its microbiological degradation to DDE and DDD, shortly after its release.     

Fate of 14C‐lindane in a rice‐fish model ecosystem*

Abstract

A model ecosystem has been used to evaluate the impact of ¹⁴C‐lindane on rice‐fish agricultural system. The distribution of ¹⁴C‐residues among the constituents of the model ecosystem was studied over a period of 90 days. The insecticide was found to be readily absorbed by the roots and translocated to all parts of the rice plant. The peak level in the shoots (26 ppm) and roots (105 ppm) of plants was reached to within three weeks. Lindane was concentrated in fish and residues as high as 90 ppm could be detected after 30 days.

The major part of the residues present in the different constituents of the ecosystem could be extracted with hexane and proved to contain soley the parent compound. The data obtained show that lindane possesses a relatively low biodegradability in fish and in rice plant. The insecticide accumulates in fish and rice plant to considerable extent.     

Metabolism of gamma‐hexachlorocyclohexah (HCH) in vivo. Metabolism of orally administered gamma‐2,3,4,5,6‐pentachlorocyclohexen (PCCH)

Abstract

Mexacarbate (4‐dimethylamino‐3,5‐xylyl N‐methylcarbamate) insecticide has potential for use in spruce budworm (Choristoneura fumiferana Clem.) control operations in Canada. Its persistence and fate in balsam fir (Abies balsamea (L.) Mill.), litter and soil samples were studied by spraying aerially oil‐based and water‐based formulations, each at 70 g A.I./ha over a coniferous forest near Bathurst, New Brunswick. The oil‐based formulation gave the maximum concentration of the chemical in the substrates studied. In fir needles, the highest concentrations observed were 0.51 ppm and 0.19 ppm (fresh weight) for the oil‐based and emulsion formulations respectively, 1 h after application. The residue levels decreased very rapidly with a half‐life of approximately 5 h. Three and eight days after the spray application of the emulsion and oil formulations respectively, the concentrations of mexacarbate in foliage decreased to trace levels ( 0.008 ppm). Only very low levels of residue were detected in litter and soil. The peak concentrations for the two formulations ranged from 0.02 to 0.11 ppm (fresh weight) in litter and from 0.01 to 0.06 ppm (fresh weight) in soil. The residue levels in both litter and soil decreased to below the detection limit (0.005 ppm) within 1 d. The ground deposit levels found on glass plates and the droplet density and size spectra measured on Kromekote® cards reflected the variations in concentrations found in fir needles, litter and soil samples and correlated with the observed maximum concentrations in them. Under the stipulated use pattern, mexacarbate concentrations found in the terrestrial components studied were low and are not likely to have any undue adverse effects on non‐target species.     

M‐(p‐Nitrobenzyl) pyridine as a spray reagent for the thin‐layer chromatographic detection of dimethyl tetrachloroterphthalate herbicide

Abstract

The developed thin‐layer chromatogram of DCPA (Dacthal) is sprayed with 4‐(p‐nitrobenzyl)pyridine chromogenic reagent followed by ammonium carbonate solution. The chromatogram is then heated in an oven at 130°C for 20 minutes. When cool, the chromatogram is sprayed with tetraethylenepentamine reagent. DCPA spots appear blue against a white background. The sensitivity of this test is about 1 μg. The procedure is useful to detect DCPA in water and in soil.     

Applications of isotope differentiation for metabolic studies with di‐(2‐ethylhexyl) phthalate

Abstract

The pervasiveness of the plasticizer di‐(2‐ethylhexyl) phthalate (DEHP) in the environment and especially in the laboratory results in a background that may cause severe interference with analytical studies. Animal‐to‐animal variability in the distribution of DEHP metabolites in excreta normally makes it necessary to use large groups of animals when different treatments are compared. Finally, radioactive tracers are usually considered undesirable for metabolic studies involving human subjects. All of these problems can be overcome through the use of muliple isotopic labels, especially ¹²C/¹³C/¹⁴C. Examples are given involving rats and monkeys, and applicability to humans is discussed. The principles involved are not limited to any particular class of test compounds. In rats, the competing pathways for metabolism of phthalate esters produce a different distribution of metabolites from a small intravenous dose of DEHP than from a large oral dose.     

Rain‐washing of mimic®, RH‐5992, from balsam fir foliage following application of two formulations

Abstract

Two formulation concentrates of the insecticide, RH‐5992 [N'‐t‐butyl‐N'‐(3,5‐dimethylbenzoyl)‐N‐(4‐ethylbenzoyI) hydrazine], an aqueous flowable (2F) and an emulsion‐suspension (ES), were diluted with water to provide spray mixes containing dosage rates ranging from 35 to 150 g of the active ingredient (AI)/ha. The mixes were sprayed in a laboratory chamber, onto balsam fir branch tips collected from field trees and greenhouse‐grown seedlings. Droplet spectra and spray mass recovery were determined on artificial samplers. Simulated rainfall of two different intensities was applied at different rain‐free periods, and rain droplet sizes were determined. Foliar washoff of RH‐5992 was assessed after application of different amounts of rain, and the increase in soil residues was evaluated.

A direct relationship was indicated between the amount of rainfall and RH‐5992 washoff. The larger the rain droplet size, the greater the amount washed off. Longer rain‐free periods made the deposits more resistant to rain. Regardless of the amount of rainfall, rain droplet size and rain‐free period, foliar deposits of the 2F formulation were washed off to a greater extent than the ES formulation. The increase in soil residues due to foliar washoff was greater for the 2F than for the ES formulation. The deposits of the emulsion‐suspension were consistently more resistant to rain‐washing than those of the aqueous flowable formulation.     

Persistence of metsulfuron‐methyl in two soils

Abstract

The persistence of metsulfuron‐methyl in sandy loam and clay soil incubated at different temperatures and moistures contents was investigated under laboratory conditions using longbean (Vigna sesquipedalis L.) as bioassay species. A significant degradation of metsulfuron‐methyl was observed in non‐autoclaved soil rather than the autoclaved soil sample. At higher temperature, the degradation rate in non‐autoclaved soil improved with increasing soil moisture content. In non‐autoclaved sandy loam and clay soil, the half‐life was reduced from 9.0 to 5.7 and from 11.2 to 4.6 days, respectively when moisture level of sandy loam increased from 20 to 80% field capacity at 35°C. In the autoclaved soil, herbicide residue seems to have been broken down by non‐biological process. The rate of dissipation was slightly increased after the second application of the herbicide to non‐autoclaved soils but not in autoclaved soil, indicating the importance of microorganisms in the breakdown process.     

Effects of alternative electron donors,acceptors, and inhibitors on 2,4‐dichlorophenoxyacetic acid and 2,4,5‐trichlorophenoxyacetic acid dechlorination in soil

Abstract

The potential for dechlorinating 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐T) in soil with a consortium showing stable dechlorinating activity was investigated. The effects of adding electron donors and/or acceptors under three anaerobic reducing conditions was compared. Results show that both 2,4‐D and 2,4,5‐T dechlorination rates were enhanced in methanogenic conditions, delayed in sulfate‐reducing conditions, and inhibited in denitrifying conditions. Also under the same three conditions dechlorination was be enhanced by the addition of lactate, pyruvate, and acetate, delayed by the addition of manganese oxide and vitamin B₁₂, and inhibited by the addition of ferric chloride. Response to treatment with such microbial inhibitors as bromoethane sulfonic acid (BESA), vancomycin, and molybdate suggests that the major bacteria involved in 2,4‐D and 2,4,5‐T dechlonnation is methanogen followed joined by sulfate‐reducing bacteria and eubacteria.     

Short‐Term Effects of Hydrogen Fluoride on Nicotiana tabacum L

Data on the short‐term effects of fumigation with hydrogen fluoride (HF) on the response behavior of the Nicotiana tabacum L. cv. St. Karabalar 6265 are being presented. Growth rate, fluoride accumulation in leaves and soils, and degradation in chlorophyll and nicotine contents of the plant species against the variations in two experimental factors, namely the exposure concentration and exposure time parameters, were investigated. Resulting data reveals that the variety selected for this study is not so tolerant to fluoride as generally reported in the literature, if only the individual effects of the pollutant is considered.     

Genotoxicity of methyl parathion in short‐term bacterial test systems

Abstract

Genotoxicity of the insecticide methyl parathion was investigated in Salmonella typhimurium and Escherichia coli bacterial test systems for the detection of back mutations and DNA‐damage. Methyl parathion was mutagenic to S. typhimurium strain TA100 after activation with rat liver microsomal and cytosolic enzymes. In DNA repair tests, methyl parathion was effective in inducing damage to the S. typhimurium strain TA1538 which lack excision repair compared to the strain TA1978 which is proficient in excision repair mechanisms. Normal laboratory light conditions had no effect on the mutagenicity tests, however, exposure of methyl parathion in the petri dish containing the tester strain TA100 and rat liver microsomal and cytosolic enzymes reduced the mutagenic activity and increased the toxic effects of methyl parathion.     

Hydrotalcites and organo‐hydrotalcites as sorbents for removing pesticides from water

Abstract

This paper reports on the adsorption of different organic pesticides by hydrotalcite, hydrotalcite heated to 500°C and organo‐hydrotalcite in aqueous medium by employing adsorption isotherms, and using X‐ray diffraction and infrared spectroscopy techniques. The results suggest that the adsorption capacity of the different materials depends on their nature as well as on the structure, polarity and hydrophobic or anionic nature of the pesticides. The results also show that hydrotalcite, both natural and after calcination at 500°C, is not a good sorbent of hydrophobic pesticides. The data demonstrated that both types of hydrotalcite, however, are very good sorbents of glyphosphate. Furthermore, the organo‐hydrotalcites may be as good sorbents as organo‐montmorillonites for hydrophobic pesticides.     

Fate and residues of 14C‐chloramphenicol in laying chickens 1

Abstract

Studies were conducted to determine the metabolic fate of chloramphenicol (CAP) in White Leghorn using the ^l4C‐labelled compound. In one experiment birds were administered orally via intra‐crop, a single dose of 100 mg (equivalent to 66 mg kg^‐1 body weight) of CAP containing 14 μCi ¹⁴C‐CAP, and its absorption, elimination and distribution in plasma were recorded. Orally dosed ¹⁴C‐compound was rapidly absorbed, efficiently distributed in plasma and eliminated in excreta (>70% in 5 hr). After 5 h, CAP equivalent residues in tissues were lower than 15 μg g^‐1 for this treatment. In a second experiment birds were given intra‐crop dose of either 0.5 or 5 mg of CAP (each dose contained 2.5 μCi ¹⁴C‐CAP) daily for five consecutive days followed by a seven day withdrawal period and elimination of ¹⁴C in excreta and eggs was monitored. More than 95% of the administered ¹⁴C was eliminated within the first 24 h after dosing. Radiocarbon (¹⁴C) was deposited preferentially in yolks compared to albumen or other tissues. Residues declined when feeding was stopped. Various metabolites were isolated and identified by a combination of TLC, LC, and LC‐MS. The main metabolic route of CAP in laying hens appears to be the glucuronidation. Cleavage of the dichloroacetate moiety was only a minor route.     

Laboratory studies on volatilization and mineralization of 14c‐p,p'‐DDT in soil,release of bound residues and dissipation from solid surfaces

Abstract

In support of field data, laboratory studies were conducted on volatilization, mineralization and binding of ¹⁴C‐p,p'‐DDT in soils at Sao Paulo. Incubation of soil for 6 weeks did not result in volatilized organics or mineralization; with >95% extractable radiocarbon in the form of p,p'‐DDT. Small amounts of bound residues (1.8%) were detected in soil. These data confirm the very slow dissipation of DDT in the field which presumably relates to the acidic pH of soil (4.5–4.8).

Bound ¹⁴C‐residues in soils treated with ¹⁴C‐p,p'‐DDT at Praia Grande and Sao Paulo could be released (5–21%) by sulphuric acid treatment. The released residue had the composition: 69–90% DDT, 7–32% DDD and 0–3% DDE. Incubation of soil bound ¹⁴C‐residues with fresh inoculum for 3 months did not result in release of ¹⁴C.

Dissipation from wooden surfaces was fairly slow. After 20 weeks, 74% of the applied radioactivity could be recovered; 44% hexane‐non‐extractable.     

The aqueous solubility of twenty‐seven insecticides and related compounds.

Abstract

The aqueous solubilities of 27 insecticides and related compounds were determined. Diazinon, fensulfothion and paraoxon had solubilities greater than reported in the literature. The presence of impurities and/or additional components in the mixture altered the measured solubility values. Addition of acetone in amounts up to 1% (volume) produced increases in parathion solubility up to 11%. The pH values of the equilibrated solubility systems were, in most instances, acidic and, in several instances, were in the pH 3–4 range.     

Impact of long‐term pesticide applications on some soil biological parameters

Abstract

The soil oxidative and anaerobic processes, as well as, the microbial biomass were followed during three years in a cotton farm (Tatuí) where the recommended pesticides have been used for several years, and in an experimental field (São Paulo) treated first time with the same pesticides. The oxidative process was monitored by the dehydrogenase (DHA)‐activity using triphenyltetrazolium chloride (TTC) as substrate. The anaerobic process was followed by the iron‐oxide reduction, and the microbial biomass was estimated by the substrate (glucose)‐indiced respiration. Increases in DHA‐activity and in the microbial biomass occurred only in the farm soil, with concomitant decreases in iron‐reduction. In the experimental field soil, the increases in DHA‐activity were followed only by decreases in iron‐reduction. Soil characteristics were the determining factor for different biological parameters after pesticide inputs. All the pesticides produced at least one clear but transient effect.