THE INSECTICIDES—Their Hazard in Industry and in the Home Part I—Chemistry and Pharmacology

Chemical, pharmacologic and toxicologic properties of the chlorinated hydrocarbon and organic phosphate insecticides have been reviewed. The chlorinated group present problems if there is either acute or chronic exposure, whereas the problems associated with the organic phosphates develop only in event of acute exposure.Chlorinated hydrocarbon insecticides accumulate in body fat depots and cause both liver and kidney damage while being metabolized and excreted. Organic phosphates destroy cholinesterase and produce effects related to overstimulation of the cholinergic branch of the autonomic nervous system. Barbiturates control the convulsions produced by the chlorinated hydrocarbon insecticides. Atropine blocks most of the effects of the organic phosphate insecticides. These compounds may be grouped in the following order of decreasing toxicity: TEPP, HETP, parathion, OMPA, ENP, aldrin, chlorophenothane, toxaphene, gamma benzene hexachloride, malathon and chlordane.     

A Study of the Chronic Effects of Insecticides in Man

Signs of possible chronic intoxication due to insecticides were sought among 441 apple-growers. A group of 170 persons living in the same environment and 162 other persons having no contact with insecticides were used as controls. It was the first attempt to determine signs of chronic intoxication by organic phosphate and chlorinated hydrocarbon insecticides. The greater incidence of leukopenia and of neurologic manifestations found among the subjects suggest that insecticides may have some chronic effects in man. This assumption is reinforced by the similarities in the findings between the subjects and the environments, and by the parallelism between the duration of exposure to insecticides and the number of affected subjects. The repetition of this study at five-year intervals seems desirable until a sufficient number of apple-growers have been studied who have been exposed to large doses of insecticides for 10, 15 or 20 years.     

Decline of chlorinated hydrocarbon insecticides residues in the tea-garden soils of Taiwan

Residues of chlorinated hydrocarbon insectidies and some of their metabolites, including p,p'-DDT, p,p'-DDD, p,p'-DDE, gamma-BHC, aldrin, dieldrin, heptachlor and heptachlor epoxide, were examined in the soils collected from 21 tea-gardens distributed in 15 countries of 6 prefectures in 1977, and from 100 locations distributed in 46 counties of 10 prefectures in 1984 in Taiwan. Although the use of these chlorinated hydrocarbon insecticides has been banned for many years, minor amounts of residues in the soils have still been detected. From 1977 to 1984, average residues of the chlorinated hydrocarbon insecticides and their metabolites in the soils of tea-gardens decreased from 5.64 to 0.06 ppb for gamma-BHC, 97 54 to 1.10 ppb for aldrin, 35.91 to 1.00 ppb for p,p'-DDE, 17.41 to 0.28 ppb for dieldrin, and 30.17 to 3.42 ppb for p,p'-DDT. But the number of positive cases increased for all chlorinated hydrocarbon insecticides tested, the residual levels were not significantly different among soils with different physiochemical properties or among soil layers. No significant amount of these insecticides was found in the processed tea.     

Effects of inorganic and organic phosphate exposure on aspects of reproduction in the common sea urchin Lytechinus variegatus (Echinodermata: Echinoidea)

The common nearshore sea urchin Lytechinus variegatus is capable of surviving exposure to inorganic phosphate concentrations as high as 3.2 mg/l(-1) and organic phosphate concentrations of 1,000 mg/l(-1). However, chronic exposure to low, medium, or high sublethal concentrations of these phosphates inhibits gonadal tissue indices and spawning activity while altering biochemical composition of gonads, reducing size frequencies of oocyte diameters, and changing gonadal volume fractions. Gonad indices declined significantly in individuals maintained in all phosphate concentrations after both one- and two-month exposures, while percentages of ripe individuals (oozing gametes upon dissection) were reduced after a two-month exposure in individuals maintained in medium and high organic phosphate concentrations. Levels of carbohydrates and lipids were lower in gonads of individuals maintained in all concentrations of both phosphates. Size frequency distributions of oocyte diameters revealed a dramatic decrease in oocyte size with increasing concentrations of both phosphates. Gonadal volume fractions of developing male and female gametes decreased with exposure to increasing phosphate levels. Volume fractions of nutritive phagocytes declined in testes of individuals held in the highest concentration of organic phosphate but displayed no significant change in ovaries. Volume fractions of mature gametes also decreased in gonads of individuals exposed to increasing concentrations of inorganic phosphate, but they remained constant in individuals exposed to all concentrations of organic phosphate. These findings indicate that shallow-water populations of L. variegatus subjected to inorganic and organic phosphate pollutants will exhibit stress that may impair reproductive output, gametogenesis, and spawning in the natural environment.     

Hematological Disorders Following Exposure to Insecticides

The medical literature dealing with hematological disorders following exposure to insecticides (chiefly chlorinated hydrocarbons and organic phosphorus compounds) is briefly reviewed. The development of blood dyscrasias as a consequence of exposure to insecticides is considered unlikely. Reported cases are few in number and often involve persons with little contact with these materials. It is often impossible to prove (or to disprove) a cause-and-effect relation in the individual case. Pointers which may be of assistance in evaluating this relationship are described. Purpura as a result of allergic vascular changes after exposure to insecticides is also discussed.     

Interactions of chlorinated hydrocarbon insecticides with membranes

Chlorinated hydrocarbon insecticides quench the fluorescence of N-alkyl derivatives of carbazole. We used phospholipids with covalently attached carbazole as probes for the interactions of chlorinated hydrocarbon insecticides with lipid bilayers, the object being to understand better the toxicities of chlorinated hydrocarbons. Fluorescence quenching measurements revealed the lipid-water partition coefficients of the chlorinated hydrocarbons, their diffusion coefficients in the membranes, and the binding capacities of the membranes for the chlorinated hydrocarbons. Active insecticides were compared with inactive analogues to test whether activities correlated with chlorinated hydrocarbon-membrane interactions. Thus DDT and methoxychlor were compared with inactive DDE, and insecticidal γ-lindane was compared with three less active stereoisomers. The partition coefficients, diffusion coefficients and membrane saturation capacities did not correlate with insecticidal potency. The partition coefficients of these chlorinated hydrocarbons were larger in bilayers containing unsaturated fatty acyl chains as compared to bilayers containing saturated fatty acyl chains. Interestingly, neural membranes are known to contain a large percentage of unsaturated lipids. Our results indicate that the activities of chlorinated hydrocarbons are not a result of specific interactions of these compounds with the lipids of membranes. However, the neurotoxicity of chlorinated hydrocarbons may be amplified by selective partitioning in the unsaturated neural membranes.     

The influence of some chlorinated hydrocarbon insecticides on the mineralization of N fertilizers and plant growth

Summary The variable effects, previously observed under field and laboratory conditions, resulting from the application of the widely used chlorinated hydrocarbon insecticides has stimulated further investigations. Because of the possible cumulative harmful effects of the insecticides on the activities of soil micro-organisms, several investigations have been concerned with the influence of these insecticides on the conversion of ammonia to nitrate.The present investigation is concerned with the relationship between the deleterious effect of certain pesticides on the activities of the soil microflora and the use of nitrogenous fertilizers; an aspect of the problem which has not previously been considered.The results of the investigation may allow the anomalous effects of the insecticides in the laboratory and in the field to be understood.The observations indicate that the basis of the effects of hexachlorocyclohexane on soils is as an inhibitor of nitrification.     

The effects of organic and inorganic phosphates on fertilization and early development in the sea urchin Lytechinus variegatus (Echinodermata: Echinoidea)

The embryos of the sea urchin Lytechinus variegatus are capable of surviving chronic exposure to inorganic sodium phosphate and organic triethyl phosphate concentrations as high as 6 and 1000 mg l(-1) seawater, respectively. However, chronic exposure to sub-lethal concentrations of these phosphates may cause arrested or abnormal embryonic development. We measured fertilization success and percentages of normal, arrested and abnormal embryos exposed to low, medium and high sub-lethal concentrations of inorganic and organic phosphate. Fertilization success was significantly reduced in all phosphate treatments. After attaining the 4-cell stage, embryos exposed to the highest phosphate concentrations displayed arrested development. Percentages of abnormally developing embryos showed a strong concentration dose-response with a significant increase in abnormal embryonic development with increasing phosphate concentration. Overall, these results indicate that the gametes and embryos of L. variegatus may provide a rapid and sensitive model bioassay for the evaluation of phosphate pollutants in marine systems. Our findings also indicate that shallow-water populations of L. variegatus spawning in areas subjected to inorganic and organic phosphate pollutants may suffer detrimental effects on fertilization and embryonic development.     

Chlorinated Hydrocarbon Insecticides: Recent Animal Data of Potential Significance for Man

The environmental persistence of chlorinated hydrocarbon insecticides is posing a serious threat to the survival of several wildlife species. Sublethal effects, completely unrelated to the insecticidal properties of these chemicals, have contributed markedly to impaired reproduction in many species and to toxicity in neonatal animals. Considering the insecticide levels found in man, are these chemicals potentially dangerous to human infants and adults? Of special concern are the potential long-term, subtle effects of low concentrations of insecticides to which many persons are ordinarily exposed. These agents affect both the peripheral and central nervous systems. They markedly elevate hepatic enzyme levels, enhancing the biotransformation of many pharmacological agents as well as interfering with endogenous steroid biosynthesis and degradation. The DDT-like insecticides are potent estrogenic agents and some have shown teratogenic and carcinogenic activity. These aspects are discussed in relation to present levels found in humans and to possible adverse effects on perinatal and adult individuals.     

Chlorinated hydrocarbon-cell membrane interactions studied by the fluorescence quenching of carbazole-labeled phospholipids: Probe synthesis and characterization of the quenching methodology

In recognition of the need to understand better the interactions of the chlorinated hydrocarbon insecticides with cell membranes we investigated the use of fluorescence quenching of membrane-bound fluorophores by these chlorinated hydrocarbons. An extensive survey of potential fluorophores identified the N-alkyl derivatives of carbazole as being especially suitable fluorophores. The fluorescence emission of these derivatives is quenched by a wide variety of commonly-used chlorinated hydrocarbons. This quenching is collisional and does not result in significant photodecomposition.Four structurally distinct carbazole-labeled phospholipids were synthesized, and their structures were confirmed by 270 MHz proton NMR and by chromatographic and chemical means. The carbazole moiety of each labeled phospholipid should be localized at a different depth in lipid bilayer. However, water soluble quenchers indicate that the fluorophores are inaccessible to the aqueous phase, irrespective of their point of attachment to the phospholipids.When incorporated into lipid bilayers, the fluorescence lifetime of these carbazole-labeled phospholipids reveals the collisional frequency between the fluorophore and the chlorinated hydrocarbon. As a result quenching of membrane-bound fluorophores may be used to measure: (1) the diffusional rate of the chlorinated hydrocarbon in the bilayer; (2) the lipid-water partition coefficient; (3) the maximum binding capacity of the membrane for the chlorinated hydrocarbon. Examples of all these measurements are given, and the fluorometric results are confirmed by direct chemical analysis.     

Demonstration of phosphates in calcium deposits: A modification of von Kossa's reaction

Summary It has been suggested that in von Kóss'as technic silver cations replace calcium bound to phosphate or carbonate groups and are then reduced to black metallic silver during exposure to light. However, in test tube experiments silver phosphate retains its yellow color for days. These differences between reactions of pure calcium phosphates and calcium deposits in tissues were emphasized already by von Kóssa; he regarded only the initial yellow coloration of calcium diagnostic for calcium phosphates and deplored the subsequent blackening caused by organic compounds. Von Kóssa's experiments were easily reproducible. A review of the literature showed that reduction of silver nitrate by organic compounds was well known in the 19th century. For histochemical studies of phosphates it was deemed desirable to avoid the formation of black by-products. Sections of paraffin-embedded human tissues were exposed to solutions of silver nitrate in subdued light or darkness and then treated with sodium thiosulfate. Silver phosphate was yellow to yellowish brown; other tissue structures remained colorless. No darkening was observed in sections stored for eight years. Other compounds which form yellow silver salts, e.g. iodides and periodates, are unlikely to occur in paraffin sections of human tissues.     

Studies on the resistance to various insecticides of a house fly strain (Diptera: Muscidae) selected with azamethiphos.

A colony of azamethiphos-resistant house flies, Musca domestica (L.), was obtained from Denmark and further selected in the laboratory with azamethiphos for four generations. LD50s for various insecticides were determined and compared with those of a susceptible house fly strain. The selected flies showed cross-resistance to all insecticides evaluated. The flies were highly resistant to most organophosphorus, carbamate, and chlorinated hydrocarbon insecticides except prothiophos, p,p'-DDT, and the pyrethroids. We conclude that the main mechanisms responsible for resistance are presumed to be factors other than acetylcholinesterase sensitivity and nerve sensitivity due to knockdown resistance.     

Investigations into mechanisms responsible for seizures induced by chlorinated hydrocarbon insecticides: the role of brain ammonia and glutamine in convulsions in the rat and cockerel

Abstract— Seizures were produced in adult female rats and in cockerels (Gallus domesticusL.) after the intracarotid administration of four structurally-unrelated chlorinated hydrocarbon insecticides. The temporal relationship of the course of the convulsions to levels in whole brain of ammonia and glutamine was examined. High levels of brain ammonia occurred in rats and cockerels poisoned acutely with lindane, dieldrin, heptachlor and DDT. The intensity of convulsions and other neurological signs coincided with and were directly correlated with the increases in brain ammonia, whereas interictal periods were associated with decreased levels of ammonia. In both species the order of drug toxicity was lindane > dieldrin > heptachlor > DDT. Significantly elevated levels of brain glutamine were induced in the cockerels after administration of all four insecticides. In contrast, increased levels of glutamine in rats were found only in those intoxicated with lindane and dieldrin. Although the ammonia-binding mechanism (conversion of free ammonia into glutamine) was saturated throughout the experiments in both the rats and cockerels, the latter were more resistant to ammonia toxicity by virtue of being able to convert free ammonia into glutamine more efficiently than rats. These data, together with data reported by others, lead to the conclusion that the four structurally-unrelated chlorinated hydrocarbon insecticides probably induced convulsions in both species by a common mechanism, involving interference with the production and/or utilization of ammonia.     

In vitro uptake and transfer of chlorinated hydrocarbons among human lipoproteins

The uptake, distribution, and exchange of chlorinated hydrocarbon insecticides (dieldrin and chlordecone) and biphenyls (2,4,5-2',4',5'-hexachlorobiphenyl and 3-chlorobiphenyl) among human lipoproteins was examined by fluorescence quenching, gel filtration, and ultrafiltration. The chlorinated hydrocarbons were rapidly taken up from solution or silica particles by lipoproteins. The distribution of chlorinated hydrocarbons among the lipoproteins was independent of the amount taken up by the lipoproteins. The partition coefficient for each lipoprotein and the serum concentration of individual lipoproteins determined the distribution pattern of chlorinated hydrocarbons among lipoproteins. The chlorinated hydrocarbons attached to albumin or one of the lipoproteins were rapidly transferred to all other lipoproteins. The exchange was complete in less than one minute. The role of rapid exchange of chlorinated hydrocarbons among lipoproteins in removal of these chemicals from blood and distribution to other tissues is discussed.     

土壤和沉积物中多氯代有机化合物厌氧降解研究进展

多氯代有机化合物(PCOCs)是土壤和沉积物中的典型污染物,厌氧条件下PCOCs能够发生脱氯发应,从而使其毒性大大降低,脱氯后形成的低氯代化合物可以进一步好氧降解,直至完全矿化。从PCOCs的降解过程出发,重点综述了几种典型PCOCs的厌氧脱氯机理以及几种重要影响因素;阐明了脱氯反应是PCOCs厌氧降解的关键步骤,反应的发生必须有还原剂提供电子,微生物的参与尤为重要;同时展望了同位素示踪法在研究PCOCs降解机制上的应用,以及开发高效降解PCOCs微生物的必要性等。     

Correlated insecticide cross-resistance in azinphosmethyl resistant codling moth (Lepidoptera: Tortricidae)

Resistance to several classes of insecticides was correlated with azinphosmethyl resistance in codling moth, Cydia pomonella (L.), in California. In tests of laboratory and field populations, cross-resistance was positively correlated with azinphosmethyl and two organophosphates (diazinon, phosmet), a carbamate (carbaryl), a chlorinated hydrocarbon (DDT), and two pyrethroids (esfenvalerate and fenpropathrin). Additionally, negatively correlated cross-resistance was identified between azinphosmethyl and two other organophosphates, chlorpyrifos and methyl parathion. Patterns of resistance observed in laboratory colonies were confirmed with field bioassays. In bioassays of field populations, azinphosmethyl resistance was observed to increase from 1991 to 1993, although levels of resistance remained < 13-fold. Because orchards with azinphosmethyl resistance have had difficulties with suppression of codling moth, and cross-resistance was found for all tested classes of insecticides, strategies for managing resistance will need to be developed so as to protect current and future control tactics. The two insecticides with negatively correlated cross-resistance are discussed as potential tools for resistance management.     

Effect of anions on the oxygen binding properties of the hemoglobin components from trout (Salmo irideus).

The effect of several anions on the oxygen equilibrium of hemoglobin components (Hb Trout I, II, and IV) from trout has been investigated.The functional properties of Hb Trout I and II are very slightly affected by organic phosphates (ATP, IHP) and pyridoxal phosphate. On the other hand the oxygen affinity of both components is affected, to the same extent, by the presence of sodium chloride; this effect seems to be pH and temperature independent. For Hb Trout I experiments on the effect of orthophosphate, pyrophosphate and pyridoxal phosphate point to a certain degree of correlation between the size of the phosphate and its effect on the functional behavior of the protein.In the case of Hb Trout I and II the differences in the effect of the various organic and inorganic phosphates may be interpreted, at a molecular level, in terms of loss of charge complementarity and (or) steric hindrance effects.On the other hand, as in the case of human hemoglobin, organic or inorganic phosphates decrease the oxygen affinity of Hb Trout IV. In addition various phosphates shift the region where the Root effect is operative toward higher pH values, thereby acting as allosteric effectors. For pyridoxal phosphate, kinetic experiments have shown that the rate of binding to Hb trout IV is several orders of magnitude smaller than that for other organic phosphates, similarly to what has been reported for human hemoglobin.     

Synthesis of fluorescent organic phosphates and their equilibrium binding to bovine oxyhemoglobin.

Fluorescent organic phosphates, beta-naphthyl diphosphate, beta-naphthyl triphosphate, and beta-naphthyl tetraphosphate, were synthesized from beta-naphthyl monophosphate using Pi and N,N'-dicyclohexylcarbodiimide. These organic phosphates were interacted with bovine oxyhemoglobin, all in no buffer, 0.1 M NaCl, at 25 degrees and in the pH range 5.5-7.0. Equilibrium binding parameters were determined by measuring the fluorescence quenching upon their interaction. It is indicated that bovine oxyhemoglobin has more than one binding site, one of which is very strong. The strength of binding to the stronger site is in the order beta-naphthyl tetraphosphate greater than beta-naphthyl triphosphate greater than beta-naphthyl diphosphate. The logarithms of association constants of these phosphates depend linearly on the net charges of these phosphates at any pH. The results were accounted for by electrostatic effects using a simple charge model. In that model, the average positive net charges in oxyhemoglobin involved in the binding of beta-naphthyl phosphate are shown as a function of pH. It is shown that the binding of these fluorescent organic phosphates is prevented reversibly by the excess addition of nonfluorescent organic and iorganic phosphates, inositol hexaphosphate, tripolyphosphate, and pyrophosphate. Assuming competitive binding in a single strong site, the association constants of these nonfluorescent phosphates were also determined by measuring the recovery of the fluorescence intensity upon the release of fluorescent phosphates. At pH 6.18, the association constant of pyrophosphate is lower than that of tripolyphosphate by one order.     

Analysis of the interaction of organic phosphates with hemoglobin.

The interaction of organic phosphates with hemoglobin is studied by use of a simple thermodynamic approach. A model-independent analysis is employed to evaluate the accuracy of Adair constants determined in the presence of 2,3-diphosphoglycerate (DPG). The change of oxygen affinity in the presence of phosphates is related to the macroscopic phosphate binding constants of oxy- and deoxyhemoglobin and used to extract such binding constants from oxygen equilibrium measurements. The change of the Bohr effect in the presence of phosphates and the competitive binding of carbon dioxide and DPG are treated quantitatively. The binding of organic phosphates is incorporated into an allosteric model, in which the effect of phosphate on both tertiary and quaternary structure changes is included. By use of this model, the factors which can be responsible for the increased functional heterogeneity of alpha and beta chains in the presence of phosphates are clarified.     

Effects of Growth-Inhibiting Substances from Young Cotton Bolls on Phosphorylation

The effects of growth-inhibiting substances from young cotton bolls on phosphorylation in both intact cotton plant and tissue slices of young cotton bolls were determined using 32P as a tracer. The results showed that the incorporation of 32P into the various organic phosphates including high-energy phosphate compounds, were decreased in abscissing bolls to about 1/2 as that of developing bolls. Infiltration of the growth-inhibiting substances into normal boll tissue caused a marked increase in respiration intensity, the synthesis of high-energy phosphate compouds was, however, decreased to 39% of that of the control tissue. When 10 ppm NAA was applied tvabscissing young cotton bolls, the incorporation of 32P into various fractions of organic phosphates increased, although never to the level of developing bolls. The above results suggested that uncoupling of respiration and oxidative phosphorylation might be one of the important effects of the growth-inhibiting substances in inducing the abscission of cotton bolls.