DDT residues: distribution of concentrations in Emerita analoga (stimpson) along coastal California

The total concentrations (tDDT) of DDT [1,1,1-trichloro-2,2-bis(pchlorophenyl)ethane], DDD [1,1-dichloro-2,2-bis(p-chlorophenyl)ethanel, and DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] in Emerita analoga from 19 California beaches reflect tDDT contamination nearby. Animals near the Los Angeles County sewer outfall contain over 45 times as much tDDT as animals near major agricultural drainage areas. Sediments near the outfall probably contain over 100 metric tons of tDDT-a reservoir for input into marine organisms. The effluent from a plant that manufactures DDT is a probable source.     

Residues of DDT in brains and bodies of birds that died on dosage and in survivors

Residues of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)-ethane (DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl)-ethane (DDD) in brains of cowbirds (Molothrus ater) killed by dietary dosage of DDT were similar in birds that died after various lengths of time on dosage and in birds that died of delayed effects after as much as 40 days on clean food. Residues of DDT and DDD, but not of 1,1-dichloro-2,2-bis-(p-chlorophenyl)-ethylene (DDE), were much lower in survivors 112 days after dosage. The relative importance of DDT and DDD in brains could not be determined, but DDE appeared not to be critical. Residues in brains of cowbirds were similar to those reported for robins, sparrows, eagles, and white rats. Residues in livers and carcass remainders (with the possible exception of DDD in the liver) appeared unsuitable for diagnosing the cause of death.     

Induced photolysis of DDT

Photolysis of mixtures of certain alkyl halides and aromatic amines produces dehalogenation of the halide. These reactions involve a photoinduced charge transfer from the amine to the halide. Photolysis of tritolylamine and carbon tetrachloride produces tritolylaminium chloride. Photolysis of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and diethylaniline at 3100 angstroms yields 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD), p,p'-dichlorobenzophenone (DDCO), and hydrogen chloride. Photolysis of DDT does not occur unless an inducer which has a low ionization potential, such as diethylaniline, is present. The DDT-diethylaniline mixture is stable in the dark, and the induced photolysis is not affected by triplet quenchers.     

Photooxidation of DDT and DDE

The pesticide DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane] and its metabolite DDE [ 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene] can be photoOxidized in methanol. Photolytic generation of free radicals that may abstract hydrogen from solvent, react with oxygen, or abstract hydrogen from unreacted substrate occurs. Further decomposition of short-lived intermediates yields many compounds. Oxidation products include benzoic acids, aromatic ketones, and chlorinated phenols. The DDE also undergoes photocyclization to give dichlorofluorene derivatives.     

Photochemical decompsosition of DDT by a free-radical mechanism

Both as a pure solid and in hexane solution, DDT readily decomposed when irradiated with ultraviolet light (2537 angstroms). Principal products identified by gas-liquid and thin-layer chromatography from irradiations of the solid phase were 1,1-dichloro-2,2-bis (p-chlorophenyl) ethane, 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene, and 4,4'-dichlorobenzophenone. 1,1-Dichloro-2,2-bis(p-chlorophenyl) ethane and hydrochloric acid were identified from irradiated solutions of DDT in hexane. On the basis of products obtained, quantum yields, scavenger experiments, and other chemical tests, a nonchain, free-radical mode of degradation is proposed.     

Degradation and disappearance of ortho, para isomer of technical DDT in living and dead avian tissues

The O,p'-DDT in technical DDT is broken down to p,p'-DDT and then to 1,1-dichloro- 2,2-bis(p-chlorophenyl)ethylene in living avian tissue. In the anaerobic conditions existing after death, O,p'-DDT is metabolized to 1,1-dichloro-2-(O-chlorophenyl)-2-(p-chlorophenyl)ethane. The absence of O,p'-DDT and metabolites in field specimens is ascribed to the rapid rate of breakdown and a masking of the 1,1-dichloro-2-(O-chlorophenyl)-2-(p-chlorophenyl)ethane residue during analysis by the relatively large amounts of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene.     

Conversion of p,p' -DDT to p,p' -DDD by intestinal flora of the rat

p,p-DDD [1,1-dichloro- 2,2-bis(p-chlorophenyl)-ethane] occurs in the feces and livers of rats, that are given p, p-DDT [1,1,1-trichloro-2,2-bis-(p-chlorophenyl)-ethane] by stomach tube, but not of rats injected intraperitoneally with p,p-DDT. Coliform bacteria, isolated from feces of control animals, can effect reductive dechlorination of p,p-DDT to p,p-DDD. These findings indicate that the normal flora of the gastrointestinal tract, rather than the liver, as others have suggested, is the major source of the p,p-DDD that is found in animals fed p,p-DDT.     

DDT reduces photosynthesis by marine phytoplankton

Concentrations of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] as low as a few parts per billion in water reduced photosynthesis in laboratory cultures of four species of coastal and oceanic phytoplankton representing four major classes of algae, and in a natural phytoplankton community from Woods Hole, Massachusetts. Toxicity to diatoms increased as cell concentration decreased. This inhibition may be of ecological importance.     

DDT residues and declining reproduction in the Bermuda petrel

Residues of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] averaging 6.44 parts per million in eggs and chicks of the carnivorous Bermuda petrel indicate widespread contamination of an oceanic food chain that is remote from applications of DDT. Reproduction by the petrel has declined during the last 10 years at the annual rate of 3.25 percent; if the decline continues, reproduction will fail completely by 1978. Concentrations of residues are similar to those in certain terrestrial carnivorous birds whose productivity is also declining. Various considerations implicate contamination by insecticides as a probable major cause of the decline.     

Adenosine triphosphatase. Sensitive to DDT in synapses of rat brain

The insecticide DDT selectively inhibits the action of a Na(+), K(+), Mg(2+)-adenosine triphosphatase found in the nerve ending fraction of the rat brain. As judged by the concentrations of inhibitors that give 50 percent of enzyme inhibition, DDT was approximately 1000 times more toxic than its non-insecticidal analog, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene. The degrees of inhibition of this enzyme system by various toxic and nontoxic DDT analogs were closely related to a general toxicity in vivo of these compounds. Moreover, the extents of inhibition of this enzyme system by DDT were much higher at low temperatures, an indication of a causal relation between poisoning in vivo by DDT and the inhibition in vitro of the Na(+), K(+), Mg(2+)-adenosine triphosphatase system.     

Polychlorinated biphenyls: toxicity to certain phytoplankters

The growth rates of two species of marine diatoms were reduced by polychlorinated biphenyls (PCB's), widespread pollutants of the marine environment, at concentrations as low as 10 to 25 parts per billion. In contrast, a marine green alga and two species of freshwater algae were not inhibited at these or higher concentrations. The sensitivity of these species to PCB's paralleled their sensitivity to DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane].     

Oxidation of persistent environmental pollutants by a white rot fungus

The white rot fungus Phanerochaete chrysosporium degraded DDT [1,1,-bis(4-chlorophenyl)-2,2,2-trichloroethane], 3,4,3',4'-tetrachlorobiphenyl, 2,4,5,2',-4',5'-hexachlorobiphenyl, 2,3,7,8-tetrachlorodibenzo-p-dioxin, lindane (1,2,3,4,5,6-hexachlorocylohexane), and benzo[a]pyrene to carbon dioxide. Model studies, based on the use of DDT, suggest that the ability of Phanerochaete chrysosporium to metabolize these compounds is dependent on the extracellular lignin-degrading enzyme system of this fungus.     

DDT: inhibition of sodium chloride tolerance by the blue-green alga Anacystis nidulans

Anacystis nidulans, a freshwater blue-green alga, has been found to lerate sodium chloride (1 percent by weight) and DDT [1,1,1-trichloro-2,2-bis chlorophenyl) ethane] (800 parts per billion) separately, but growth was inhibited in the presence of both compounds. This inhibition was reversed by an increased calcium concentration. It is possible that inhibition of (Na+,K+)-activated adenosine triphosphatase) by DDT causes this species to lose the ability to lerate sodium chloride.     

Synergism of insecticides by herbicides

The herbicides atrazine, simazine, monuron, and 2,4-D (2,4-dichlorophenoxyacetic acid) enhanced the toxicity of selected insecticides to Drosophila melanogaster Meigen, Musca domestica L., and larvae of Aedes aegypti L. The insecticides-nine organophosphorus compounds, two chlorinated hydrocarbons, and one carbamate-were used at dosages that resulted in low insect mortalities, while the herbicides by themselves were nontoxic. Atrazine was most effective. With increasing amounts of this herbicide and constant amounts of some insecticides, increasing mortalities of fruit flies were observed. Exposure of the insects for 24 hours to carbofuran (0.5 microgram), p,p'-DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] (4 micrograms), parathion (0.35 microgram), and diazinon (0.2 microgram) alone resulted in mortalities of 7.5, 9.5, 8, and 10.5 percent, respectively. Based on dosage mortality curves obtained with increasing amounts of atrazine, mortalities of 50 percent of the insect populations would have been achieved with 23, 40, 6, and 10 micrograms of atrazine added to the abovementioned dosages of carbofuran, DDT, parathion, and diazinon, respectively.     

A COLORIMETRIC METHOD FOR THE MICRO-DETERMINATION OF 2,2, BIS(P-CHLOROPHENYL) 1,1,1 TRICHLORETHANE (DDT)

A colorimetric method for the micro-determination of 2,2 bis(p-chlorophenyl) 1,1,1 trichlorethane (DDT) is presented. The test is based on the discovery that when DDT is heated in an anhydrous pyridine solution containing xanthydrol and solid potassium hydroxide a red color develops, which under proper conditions is proportional to the amount of DDT present. The reaction is sensitive to as little as 10 gammas of DDT. It will detect small differences in concentration within the range of 10 to 200 gammas. The test is relatively simple and can be run in a comparatively short time.     

北京市农田土壤中有机氯农药残留的空间分析

【目的】通过在北京平原区农田采取的131个表层土壤样品的化验分析，研究土壤中有机氯农药六六六（HCH）和滴滴涕（DDT）残留总量及异构体、代谢物含量的空间变异特征。【方法】样品测定结果采用传统统计分析，半方差结构和模型拟合的地统计分析以及结合普通Kriging 和反比距离插值方法进行分析。【结果】传统统计分析表明，土壤中残留HCH和DDT的异构体、代谢物及总量均服从对数正态分布，并全部属于强变异。基于半方差结构和模型拟合的地统计分析， -HCH、 -HCH和HCH总量没有空间变异结构方差，而其它农药含量存在空间变异结构方差、且可分别用指数模型或高斯模型拟合。模型拟合的结果看出α-HCH、DDT总量及其异构体以较大范围的变异为主（变程大于18 km），而 -HCH的变程只是2.73 km。趋势分析表明DDT的异构体、代谢物及总量都存在明显的趋势效应，而HCH及其异构体中只有 -HCH 和 -HCH略有趋势效应。结合普通Kriging和反比距离插值方法，获得了土壤有机氯农药残留含量的等值线图，并分析了其空间分布规律。【结论】所有土壤样本中的六六六含量和 85%的土壤样本的滴滴涕农药含量均达到国家《土壤环境质量标准》(GB15618-1995)一级标准（<0.05 mg·kg-1），残留污染较轻。     

Conversion of DDT to DDD by pathogenic and saprophytic bacteria associated with plants

Of 27 microorganisms examined, 23 plant pathogenic and saprophytic bacterial species were found to convert p,p' DDT to p,p' DDD under anaerobic conditions. The range of conversion of DDT (10 micrograms per milliliter) during an incubation of 14 days was from a trace to over 5 micrograms per milliliter, with the majority of the bacteria showing the greatest activity during the final 7-day period. There is evidence that metabolites of DDT other than DDD are also produced.     

Microsomal hydroxylase induction in liver cell culture by phenobarbital, polycyclic hydrocarbons, and p,p'-DDT

Aryl hydrocarbon hydroxylase induction by phenobarbital, polycyclic hydrocarbons, and the insecticide, 2.2-bis(p-chlorophenyl)-1,1,1-trichloroethane (p,p'-DDT), occurs in rat fetal liver cell cultures. The maximum net rate at which the hydroxylase activity accumulates is about the same when phenobarbital, 3-methlcholanthrene, or benz[a]anthracene is in the growth medium at optimum concentrations. An additive effect is obtained when either phenobarbital or p.p'-DDT is present with a polycyclic hydrocarbon in the growth medium, but not when the cells are treated with phenobarbital plus p.p'-DDT or with the combination of two polycyclic hydrocarbons.     

Anaerobic biodegradation of DDT to DDD in soil

DDT labeled with carbon-14 was added to soil, and the mixture was incubated anaerobically for 2 weeks and 4 weeks. DDT and seven possible decomposition products were separated by thin-layer chromatography, and the radioactivity of material from individual spots was determined by liquid scintillation. The DDT was dechlorinated by soil microorganisms to DDD, and only traces of other degradation products were detected. No degradation of DDT was detected in sterile soil.     

Deposition of DDE and polychlorinated biphenyls in dated sediments of the Santa Barbara basin

Analysis of dated oceanic sediments from the Santa Barbara Basin of the Southern California Bight has shown that deposition of polychlorinated biphenyls (PCB) began about 1945 and that DDE [1,1-dichloro-2-2-bis(p-chloro-phenyl)ethylene] first appeared in sediments deposited about 1952. Concentrations of both show a progressive increase through 1967; estimated deposition rates (in grams per square meter per year) in 1967 of DDE and PCB were 1.9 x 10(-4) and 1.2 x 10(-4), respectively.