Endocrine modifications produced by o,p′-DDT in the male adult rat

The action of o,p′-DDT on plasma steroids and steroidogenesis in adrenal and brain tissues has been studied using 26 Sprague-Dawley adult male rats. The animals were divided into three groups: the first was injected with sesame oil, the second injected with 20 mg of o,p′-DDT in 0.5 ml of sesame oil and the third group was not treated. The animals were sacrificed 8 hr after the injection; blood, adrenal, and brain were removed and used for plasma steroid determinations. A decrease in testosterone and an increase in estradiol were found in plasma of treated animals. The injection of o,p′-DDT produced also a decrease in corticosterone formed from progesterone and in unchanged progesterone in the adrenal glands, an increase in dihydrotestosterone and a decrease in androstenediol formation from testosterone in the brain. These results indicate that the effect of o,p′-DDT administration implies: (i) a general decrease in androgen biosynthesis, which is evident also from the lower level of plasma testosterone; (ii) a decrease of plasma estradiol level, which could indicate a binding of o,p′-DDT to estradiol receptor sites; (iii) a decrease in 11β-hydroxylase activity, which is evident from the lower amount of corticosterone formed from progesterone in the adrenal tissue.     

Long-term effects of DDT on the behavior and central nervous system activity in Periplaneta americana

The effects of p,p′-DDT and four of its analogs on electrical activity in the central nervous system of the cockroach, Periplaneta americana (L.), were investigated. Cockroaches were injected intraabdominally with an organochlorine compound at LD₅₀ 96-hr doses (except for p,p′-DDE). Extracellular recordings were made from the central nervous system at 1 hr, 24 hr, or 3 weeks postinjection. p,p′-DDT, methoxychlor, and p,p′-DDD induced behavioral changes (tremors, jitters, hyperexcitability) and repetitive firing in the central nervous system prior to 1 hr postinjection. By 24 hr postinjection, most behavioral signs of poisoning had disappeared, though repetitive firing could still be readily elicited in the central nervous system. Cockroaches injected with o,p′-DDT, however, usually required about 48 hr before overt signs of poisoning became apparent. Cockroaches treated with p,p′-DDT or o,p′-DDT behaved normally at 3 weeks postinjection but still displayed a significant occurrence of repetitive firing in the central nervous system. A mechanism is proposed to explain how a cockroach might recover behaviorally from a sublethal dose of an organochlorine compound but still display repetitive firing in its central nervous system. A direct “cause and effect” relationship between repetitive firing in the central nervous system and mortality (and external signs of poisoning) is therefore questioned.     

Excretion of DDT residues into milk of the Indian buffalo,Bubalus bubalis (L.) after oral and dermal exposure

Three groups of buffaloes were fed with 20, 100 and 400 mg of p,p′-DDT in their daily rations. The DDT residues in the milk fat of the treated animals showed an initial rapid rise but soon attained a dose-dependent equilibrium. The transfer coefficient of DDT residues in milk at ‘plateau’ levels showed an average value of about 12%. Half-life values for the rate of decline of DDT residues during the post-dosing period were computed according to a two-open-compartment model. Dermal application of p,p′-DDT to buffaloes also resulted in excretion of a significant amount of its residues in milk. TDE was the predominant compound present in milk when buffaloes had ingested p,p′-DDT, whilst p,p′-DDT itself was present in greater quantity than its metabolites when animals were treated dermally.     

Comparative excretion of DDT analogues into milk of indian buffalo,Bubalus bubalis L. following oral administration

Four groups of Indian buffaloes were fed daily with 25 mg of p,p′-DDT p,p′-TDE p,p′-DDE or o,p′-DDT for 100 days. Milk was analysed for organochlorine residues during this period and also for 100 days after pesticide administration had been discontinued. For the period showing ‘plateau level’ residues, 17.2% of p,p′-DDE, 17% of p,p′-TDE, 14% of p,p′-DDT as p,p′-DDT (3.5%); p,p′-TDE (10.5%); 3.2% of p,p′-DDT as o,p′-DDT (1.3%) and o,p'-TDE (1.9%) of their administered amounts were excreted in the milk. Since these compounds were excreted at different rates, the residue levels in the milk expected from a given feed would depend on their concentration and proportional distribution in the feed. The maximum tolerable content of DDT analogues in feed was derived to be 0.1 mg kg^?1 (dry weight basis) by using the maximum accumulation coefficient and incorporation of the necessary safety margin. It is concluded that Indian buffaloes fed with rations contaminated with a total of DDT analogues below this limit will yield milk of acceptable quality. Following the termination of feeding with contaminated rations, the elimination of p,p′-DDE in the milk took the longest time and that of o,p′-DDT the shortest. These results suggest that the time required for the initial high residue concentration to decline to less than the legal limit would be determined by the relative amounts of DDE, TDE and DDT in the milk, after elimination of the potent source of contamination.     

The metabolism of p,p′-DDT by the feral pigeon (Columba livia)

Male feral pigeons were dosed with ring-labeled $\text{[}{}^{14}\text{C}\text{]p,p′-}\text{DDT}$ and the tissues and droppings analyzed for total ¹⁴C, extractable ¹⁴C, and metabolites. Only 16% of an intraperitoneal dose of 1.5–2.2 mg kg^?1 was voided in the droppings over 28 days; the rate of loss reached a maximum on the 14th day and then fell quickly away. The rate of removal of ¹⁴C in droppings was low in comparison to that found in the rat and the Japanese quail. When pigeons were dosed with 32–38 mg kg^?1 DDT per bird, and killed after 77 days, 5.4% of the dose was eliminated in droppings and 87% was recovered in the body. The tissues and droppings from this experiment were analyzed for DDT and its metabolites. Of the ¹⁴C remaining in tissues 88% was accounted for as the apolar compounds DDE, DDT, and DDD. Approximately half of the ¹⁴C in droppings was present as DDE, DDT, and DDD, whereas 27–35% was apparently in conjugated form, extractable from aqueous solutions by ethyl acetate after prolonged acid hydrolysis. Two polar metabolites were isolated from the acid-released material. One was p,p′-DDA; the other was extractable from aqueous solution at pH 8 and was tentatively identified as a monohydroxy derivative of p,p′-DDT. DDE accounted for 93% of the ¹⁴C present as metabolites in tissues and droppings, clearly indicating the importance of this intermediate in this study. The metabolism of DDT in the feral pigeon is discussed in relation to its metabolism by other species.     

Distribution and breakdown of DDT in orchard soil

Amounts of DDT and its breakdown products were determined in soil in an apple orchard in Herefordshire. Samples were taken for a number of years (1972–79) after use of the insecticide in the orchard had ceased in 1969. The results were compared with those obtained in an investigation of the same orchard in 1968. From 1968 to 1979, soil residues of pp′-DDT, p′--DDT and pp′--TDE decreased gradually whereas those of pp′--DDE increased, and there were linear relationships between log (concentration) and time. The calculated time for 50% decrease in concentration (Dt₅₀) was 11.7 years for pp′--DDT, 3.3 years for pp′--TDE and 7.1 years for op′--DDT; the time for doubling the concentration for pp′--DDE was 9.1 years. Regression analysis on the two major components (pp′--DDT+pp′--DDE) indicated that the total amount (2.7 mg kg^?1) was not decreasing with time. It was concluded that during a post-spray era, the breakdown of pp′--DDT to pp′--DDE was a significant feature of the persistence of DDT, and that, in contrast to the findings of other workers who sampled when DDT was being used, there were no losses by volatilisation. There was an exponential decrease in the amount of DDT residues with increasing soil depth and approximately 90% was found in the top 10 cm of the undisturbed soil profile.     

The effects of DDT analogs upon potassium conductance in synthetic membranes

The effects of p,p′-DDT and 13 analogs were studied upon the K⁺ conductance which valinomycin induces in a lecithin-octane bilayer. Eight compounds decreased conductance, 4 relatively polar analogs increased conductance, and one had no effect. A partial correlation of these variations with physiological effects upon cockroach nerve and crayfish giant axon was found. Evidence was presented that the effect on the bilayer was due to an effect of the compounds on the fluidity of the membrane's interior rather than a direct interaction with the valinomycin.     

The effect of some DDT and methoxychlor analogs on temperature selection and lethality in brook trout fingerlings

The effects of several DDT and methoxychlor analogs on trout fingerling temperature selection and lethality were investigated. The molecular requirements for lethality and alteration of temperature selection were different. Only p, p′-DDT, p, p′-DDD, and p, p′-methoxychlor were toxic in the range 10–50 ppb used. All the compounds tested, except DDE-type analogs, altered temperature selection. The effect of p, p′-methoxychlor on temperature selection progressively decreased until normal values were obtained 5 days after exposure. The effect of p, p′-DDT was still pronounced 9 days after exposure.     

Inhibition of acetyl-coenzyme a carboxylase by coenzyme a conjugates of grass-selective herbicides

A total of 146 samples of different kinds of cheeses produced in Spain were analysed in order to ascertain the specific contamination pattern. The organochlorine compounds studied were those most commonly investigated in previous surveys: α-HCH, β-HCH, γ-HCH (lindane), γ-HCH, chlordane, aldrin, dieldrin, endrin, heptachlor, heptachlor epoxide, and the isomers and metabolites of DDT. α-HCH, β-HCH, γ-HCH, chlordane, p,p′, DDT, and p,p′-DDE were found in more than 76% of samples; p,p′-DDE and γ-HCH were the most frequently detected, with frequencies of 100 and 97.9% respectively. γ-HCH, aldrin, dieldrin, heptachlor, heptachlor epoxide, o,p′-DDT, p,p′-DDD and o,p′-DDD were observed at lower frequencies. No residues of endrin were detected in any sample. Insecticides exceeding the maximum residue limits (MRLs) were chlordane, β-HCH, α-HCH and γ-HCH, with 42, 20, eight and six samples respectively. Mean residues of organochlorines found were as follows (μ kg^?1 butterfat): α-HCH = 46.3; β-HCH = 46.5; γ-HCH = 54.2; δ-HCH = 16.9; aldrin = 16.7; dieldrin = 9.7; heptachlor = 15.9; heptachlor epoxide = 14.8; chlordane = 50.2; o,p′-DDT = 5.1; p,p′-DDT = 12.4; o,p′-DDT = 19.6; p,p′-DDD = 46.7; o,p′-DDE = 6.9; p,p′-DDE = 40.7 (.DDT = 55.0). Estimated dietary intakes (EDIs) from cheese consumption were compared to acceptable daily intakes (ADIs) for the pesticides where residues exceeded the MRL. EDIs calculated were in all cases below ADIs, and, therefore, based on the ADIs, there is no health risk involved in the consumption of cheese from Spain arising from organochlorine residues.     

Residues of zeta‐cypermethrin in bovine tissues and milk following pour‐on and spray application

The depletion of zeta‐cypermethrin residues in bovine tissues and milk was studied. Beef cattle were treated three times at 3‐week intervals with 1 ml 10 kg^?1 body weight of a 25 g litre^?1 or 50 g litre^?1 pour‐on formulation (2.5 and 5.0 mg zeta‐cypermethrin kg^?1 body weight) or 100 mg kg^?1 spray to simulate a likely worst‐case treatment regime. Friesian and Jersey dairy cows were treated once with 2.5 mg zeta‐cypermethrin kg^?1 in a pour‐on formulation. Muscle, liver and kidney residue concentrations were generally less than the limit of detection (LOD = 0.01 mg kg^?1). Residues in renal‐fat and back‐fat samples from animals treated with 2.5 mg kg^?1 all exceeded the limit of quantitation (LOQ = 0.05 mg kg^?1), peaking at 10 days after treatment. Only two of five kidney fat samples were above the LOQ after 34 days, but none of the back‐fat samples exceeded the LOQ at 28 days after treatment. Following spray treatments, fat residues were detectable in some animals but were below the LOQ at all sampling intervals. Zeta‐cypermethrin was quantifiable (LOQ = 0.01 mg kg^?1) in only one whole‐milk sample from the Friesian cows (0.015 mg kg^?1, 2 days after treatment). In whole milk from Jersey cows, the mean concentration of zeta‐cypermethrin peaked 1 day after treatment, at 0.015 mg kg^?1, and the highest individual sample concentration was 0.025 mg kg^?1 at 3 days after treatment. Residues in milk were not quantifiable beginning 4 days after treatment. The mean concentrations of zeta‐cypermethrin in milk fat from Friesian and Jersey cows peaked two days after treatment at 0.197 mg kg^?1 and 0.377 mg kg^?1, respectively, and the highest individual sample concentrations were 2 days after treatment at 0.47 mg kg^?1 and 0.98 mg kg^?1, respectively. © 2001 Society of Chemical Industry     

Chlorpyrifos-methyl plus bioresmethrin; Methacrifos; Pirimiphos-methyl plus bioresmethrin; and synergised bioresmethrin as grain protectants for wheat

Field trials with various pesticide combinations were carried out on bulk wheat in commercial silos in Queensland, South Australia and Western Australia. Laboratory bioassays on samples of treated grain at intervals over 8 months using malathion-susceptible and malathion-resistant strains established the following orders of efficacy: against Sitophilus oryzae (L.), chlorpyrifos-methyl 10 mg kg^?1 + bioresmethrin 1 mg kg^?1 = methacrifos 15 mg kg^?1 in aerated storage > pirimiphos-methyl 4 or 6 mg kg^?1 + bioresmethrin 1 mg kg^?1 = bioresmethrin 4 mg kg^?1 + piperonyl butoxide 16 mg kg^?1; against Rhyzopertha dominica (F.), bioresmethrin 4 mg kg^?1 + piperonyl butoxide 16 mg kg^?1 > methacrifos 15 mg kg^?1 > chlorpyrifos-methyl 10 mg kg^?1 + bioresmethrin 1 mg kg^?1 = pirimiphos-methyl 4 or 6 mg kg^?1 + bioresmethrin 1 mg kg^?1. All treatments completely prevented production of progeny in Sitophilus granarius (L.), Tribolium castaneum (Herbst), T. confusum Jackquelin du Val and Oryzaephilus surinamensis (L.). The biological efficacy of methacrifos was greater and the rate of degradation lower in aerated than in non-aerated storage. Residue levels of all compounds were determined chemically and were below proposed international residue levels to be considered by the Codex Alimentarius Commission.     

The dietary toxicity of flocoumafen to hens: Elimination and accumulation following repeated oral administration

In a dietary toxicity study, laying hens received a diet containing the rodenticide flocoumafen at concentrations of 1.5, 5, 10 and 50 mg kg^?1 for five consecutive days. The LC₅₀ at termination following a 28-day observation period was 16.4 mg kg^?1. Livers of birds which received doses of flocoumafen between 5 and 50 mg kg^?1 had concentrations of flocoumafen (1.5 nmol g^?1) that were independent of dose. The data indicate the presence in hen liver of a saturable high-affinity flocoumafen binding site with similar characteristics and capacity to that of the quail and rat. Residues of flocoumafen in samples of breast and leg muscle were low in all exposure groups. Higher, dose-related residues were found in samples of abdominal fat and skin-associated fat and there was a clear demonstration of the transfer of dose-related residues into eggs. In a separate study in which hens were dosed with [¹⁴C]flocoumafen for five consecutive days at a daily rate of 1 and 4 mg kg^?1 body weight, the majority (68 %) of the daily radioactive dose was eliminated over the following 24 hours via excreta. Residues in liver at death or when killed accounted for < 1 % of the cumulative administered radioactivity. Residues in eggs were located primarily in the yolk with maximum concentrations 1.0 mg kg^?1 or 0.18% of the low dose; 2.1 mg kg^?1 or 0.06% of the high dose as [¹⁴C]flocoumafen equivalents were observed at 10 days after start of dosing. Some 40 % of the total activity in the yolk was unchanged flocoumafen.     

The metabolism of tefluthrin in the goat

A goat was dosed orally with [¹⁴C]tefluthrin, twice daily for 4 days, at a rate equivalent to 10.9 mg kg^?1 in its diet. Within 16 h of the final dose, 70.1% of the dose had been excreted (urine 41.4%, faeces 28.7%). Extensive metabolism occurred in the goat by ester cleavage and oxidation at a variety of positions on the molecule. Low radioactive residues were detected in the milk (0.076 mg kg^?1), fat (0.076 mg kg^?1) and muscle (0.016 mg kg^?1), with tefluthrin as the largest individual component of the residue (milk 66.5%, fat 76.7%, muscle 34.2%). Higher residues were present in the kidney (0.3 mg kg^?1) and liver (1.0 mg kg^?1) and only a small percentage of this residue was due to tefluthrin (kidney 3.4%, liver 6.1%). The remainder of the residue in the kidney and liver was a complex mixture of metabolites. Most of the kidney metabolites were identified, but a high proportion of the liver residue was due to six unidentified polar compounds.     

Organophosphorothioates and synergised synthetic pyrethroids as grain protectants on bulk wheat

Organophosphorothioates and synergised synthetic pyrethroids were used in duplicate field trials carried out on bulk wheat in commercial silos in Queensland and New South Wales. Laboratory bioassays using malathion-resistant strains of insects were carried out on samples of treated grain at intervals over 9 months. These established that all treatments were generally effective. Deltamethrin (2 mg kg^?1)+ piperonyl butoxide (8 mg kg^?1), fenitrothion (12 mg kg^?1)+ fenvalerate (1 mg kg^?1)+ piperonyl butoxide (8 mg kg^?1), fenitrothion (12 mg kg^?1)+ phenothrin (2 mg kg^?1)+ piperonyl butoxide (8 mg kg^?1) and pirimiphos-methyl (4 mg kg^?1)+ permethrin (1 mg kg^?1)+ piperonyl butoxide (8 mg kg^?1) controlled common field strains of Sitophilus oryzae (L.) and Rhyzopertha dominica (F.). Against a highly resistant strain of S. oryzae, deltamethrin (2 mg kg^?1)+ piperonyl butoxide (8 mg kg^?1) was superior to the remaining treatments. All treatment combinations completely prevented progeny production in Tribolium castaneum (Herbst), T. confusum Jacquelin du Val and in Ephestia cautella (Walker). Residues of deltamethrin, fenvalerate, permethrin and phenothrin were determined and shown to be highly persistent on stored wheat. During milling, residues accumulated in the bran fractions and were reduced in white flour. They were not significantly reduced during baking.     

Grain protectants for the control of malathion-resistant insects in stored sorghum

Duplicate experiments were carried out on bulk sorghum stored in South Queensland and in Central Queensland. Bioassays of treated grain, conducted during 6 months' storage, established that fenitrothion (12 mg kg^?1)+ bioresmethrin (1 mg kg^?1), and pirimiphos-methyl (4 mg kg^?1)+ carbaryl (8 mg kg^?1), controlled typical malathionresistant strains of Sitophilus oryzae (L.), Rhyzopertha dominica (F.), Tribolium castaneum (Herbst), and Ephestia cautella (Walker). Chlorpyrifos-methyl (10 mg kg^?1)+ pyrethrins (1.5 mg kg^?1)+ piperonyl butoxide (12 mg kg^?1), and fenitrothion (12 mg kg^?1)+ (1R)-phenothrin (1 mg kg^?1), also controlled the strains of S. oryzae, T. castaneum and E. cautella, but were only partly effective against R. dominica. Methacrifos (15 mg kg^?1) controlled all the tested species except E. cautella. Chemical assays established that the residues and rates of breakdown of these grain protectants on sorghum conformed to the general pattern for other cereal grains; residues from the above treatments were below the individual Maximum Residue Limits recommended by the Codex Alimentarius Commission.     

Residues of synthetic pyrethroid insecticides on horticultural crops

Foliar applications of synthetic pyrethroids were made to several crops to determine residue levels at various intervals after application. On onions, residues of cypermethrin, permethrin and fenvalerate were negligible > 0.1 mg kg^?1, 7 days after application. On lettuce, residues of fenvalerate and permethrin were 0.8 mg kg^?1. On celery, residues of fenvalerate did not decline and ranged from 0.12 to 0.25 mg kg^?1 during the 14-day period. On green bush-beans, residues of permethrin and cypermethrin did not decline during the 14-day period and ranged from 0.1 to 0.6 mg kg^?1. By day 7, residues of cyfluthrin, cypermethrin, deltamethrin, fenvalerate and permethrin on strawberries were less than the acceptable maximum tolerance of 0.1 mg kg^?1 with the exception of cypermethrin, applied at the rate of 0.14 kg a.i. ha^?1 which gave a residue of 0.14 mg kg^?1.     

A rapid high-pressure liquid chromatographic method for the determination of carbaryl residues in wheat grain

Carbaryl residues in wheat grain have been determined in methanol extracts using normal-phase high-pressure liquid chromatography (h. p. l. c.) with ultraviolet detection. A single-injection, clean-up and analysis technique was used to allow more rapid analysis of samples after extraction. A detection limit of 0.1 mg kg^?1 in a 50 g sample of wheat was achieved. Recoveries of 86% at the 1 mg kg^?1 level and 90-99% at the 5 mg kg^?1 level were obtained for fortified grain samples. Methanol was found to be a superior extractant for carbaryl from wheat when compared with hexane, acetone and dichloromethane. Twelve samples containing aged carbaryl residues were analysed by the h. p. l. c. technique and by a colorimetric procedure which allowed statistical analysis of errors. For the h. p. l. c. method (excluding sampling error), a relative standard deviation of 4.4% was obtained.     

Alkylation of guanine in mice in vivo by organophosphorus insecticides. I. Trichlorphone and butonate

Following intraperitoneal administration to male mice of trichlorphone, 4 mg/animal = 160 mg/kg and butonate, 5 and 10 mg/animal = 200 and 400 mg/kg, labeled by ¹⁴C in the OCH₃-groups, nucleic acids taken from different organs and urine were analyzed for [7-¹⁴C]methylguanine. The limit of detection was 2 × 10^?8, calculated as ¹⁴C relative to the total dose. The maximum of ¹⁴C in 7-methylguanine was 2 × 10^?7 in lung, kidney, and testicles and 3 × 10^?6 in liver. The excretion rate of 7-MeG from nucleic acids is very rapid, a halflife of 2.0 hr was measured in liver from butonate and of < 24 hr was calculated in the whole body from trichlorphone, contrary to the excretion rate of 3.0–3.5 days following administration of strongly genotoxic agents. The relative amounts of [7-¹⁴C]methylguanine excreted in the urine were determined and compared with data for dichlorvos, dimethyl sulfate, and methyl methanesulfonate from the literature. Following intraperiotoneal administration, the methylating capability towards N-7 of guanine in nucleic acids is given by the ratio of about 100:10:25 for dichlorvos, butonate, and trichlorphone, respectively.     

Gamma-HCH in eggs and poultry arising from exposure to thermal vaporisers

Levels of gamma-HCH have been determined in poultry tissue and eggs taken from poultry houses in which thermal vaporisers were operated. During continuous operation for 14 months, residue levels of gamma-HCH in both substrates were related closely to changing levels of insecticide in the vaporiser; up to 46 mg kg^?1 (on a fat basis) was found in tissue and up to 4.0 mg kg^?1 (on a whole liquid basis) in eggs. Where the vaporisers were operated discontinuously, maximum levels were 6.7 mg kg^?1 in tissue and 0.53 mg kg^?1 in eggs.