Lindane

Lindane is an organochlorine pesticide that has been used both as agricultural insecticide and as a pharmaceutical treatment. As a consequence of its toxic, suspected carcinogenic, persistent, bioaccumulative and suspected endocrine disrupting properties, lindane became a substance of scrutiny for countries in the European Community. Lindane concentrations in biota samples collected far away from use areas is similar to that observed for other organochlorine pesticides, confirming the concern for persistence, bioaccumulation and long-range transport. Lindane is being considered for inclusion in the Stockholm Convention on persistent organic pollutants, which would ban its production and use worldwide. Lindane (g-hexachlorocyclohexane, g-HCH) was used as an insecticide on fruit and vegetable crops, for seed treatment and in forestry. It was also used as a therapeutic pesticide in humans and animals. Several countries have restricted the use of Lindane. Lindane can be degraded in soil under aerobic conditions; the half-life ranges from 88 to 1146 days. gamma-pentachlorocyclohexene, hexa-, penta-, tetra- and trichlorobenzenes and penta- and tetrachlorophenols are the degradation products most commonly found. Anaerobic degradation is more rapid than aerobic degradation under laboratory conditions (half-life 12–174 days). Under anaerobic conditions, the same chlorinated benzenes and hexenes are found, but not the phenols. Leaching of Lindane to groundwater rarely occurs, and in surface waters, Lindane can be removed by evaporation. Ultraviolet light seems to transform gamma-HCH into alpha-HCH to some extent. Bacteria also influence the isomerization of gamma-HCH to alpha-HCH. The degradation products found in soils have also been found in water. In surface waters, Lindane can be removed by evaporation.

An organochlorine pesticide of moderate mammalian toxicity which is degraded slowly in the environment and can accumulate in mammalian tissues.

Lindane has been used as a broad-spectrum insecticide, which acts by contact, for both agricultural and non-agricultural purposes. Lindane has been used for seed and soil treatment, foliar applications, tree and wood treatment and against ectoparasites in both veterinary and human applications. As a consequence of its toxic, suspected carcinogenic, persistent, bioaccumulative and suspected endocrine disrupting properties, lindane became a substance of scrutiny for countries in the European Community. All uses of HCH including lindane have been banned, but Member States may allow technical HCH for use as an intermediate in chemical manufacturing and in products with at least 99% of the isomer content in the gamma form (lindane) for public health and veterinary topical use only, until December 31^st 2007. Lindane was included in the Stockholm Convention on persistent organic pollutants, which bans its production and use worldwide (SC POPs).

Considering every ton of lindane produced generates approximately 6 - 10 tons of other HCH isomers, a considerable amount of residues was generated during the manufacture of this insecticide. For decades, the waste isomers were generally disposed of in open landfills like fields and other disposal sites near the HCH manufacturing facilities. After disposal, degradation, volatilization, and run off of the waste isomers occurred. If the estimate of global usage of lindane of 600,000 t between 1950 and 2000 is accurate, the total amount of possible residuals (if it is assumed that a mean value of 8 t of waste isomers are obtained per ton of lindane produced) amounts to possibly 4.8 million t of HCH residuals that could be present worldwide giving an idea of the extent of the environmental contamination problem. Air releases of lindane can occur during the agricultural use or aerial application of this insecticide, as well as during manufacture or disposal. Also, lindane can be released to air through volatilization after application. Evaporative loss to air from water is not considered significant due to lindane's relatively high water solubility.

Lindane is very prevalent in the marine environment and soils, with higher concentrations often found in colder regions. The atmospheric long range transport potential of lindane has been demonstrated for the European Region. Although current production of lindane seems to be declining with only a few producing countries remaining, the inefficient production process used to manufacture this insecticide over the years has been a world wide contamination problem which has left, and might still be leaving behind, an enormous legacy of contaminating waste products. The evaluation of laboratory experimental data of lindane would suggest a lower potential of bioaccumulation and biomagnification than that expected for other organochlorine pesticides. In fact, lindane should be considered a border case in terms of its potential for bioaccumulation. Fortunately, there is a large amount of monitoring data on biota allowing a real estimation of the risk profile of lindane in comparison with other organochlorine pesticides. The information provided by this huge amount of real field data is conclusive: lindane concentrations in biota samples collected far away from use areas is similar to that observed for other organochlorine pesticides, confirming the concern for persistence, bioaccumulation and long-range transport. Lindane was toxic to the kidney and liver after administration orally, dermally or by inhalation in short-term and long-term studies of toxicity and reproductive toxicity in rats. The renal toxicity of Lindane was specific to male rats and was considered not to be relevant to human risk assessment, since it is a consequence of accumulation of a2u-globulin, a protein that is not found in humans. Hepatocellular hypertrophy was observed in a number of studies in mice, rats and rabbits and was reversed only partially after recovery periods of up to 6 weeks. Lindane did not induce a carcinogenic response in rats or dogs, but it caused an increased incidence of adenomas and carcinomas of the liver in agouti and pseudoagouti mice, but not in black or any other strains of mice in a study of the role of genetic background in the latency and incidence of tumorigenesis. Joint FAO/WHO Meeting on Pesticide Residues (JMPR) has concluded that there was no evidence of genotoxicity.

Mild symptoms of poisoning are nausea, vomiting, restlessness, tremor and apprehension. Lindane volatilized from heat vapourizers may produce great irritation of the nose, eyes and throat with nausea and severe headache. Urticaria may occur in sensitive individuals. More serious and advanced symptoms are repeated, violent clonic convulsions sometimes superimposed on a continuous tonic spasm. Respiratory difficulty and cyanosis secondary to the convulsions may occur. High fever may also result. Death appears to be due to heart and respiratory failure. Reports of blood dyscrasias have not been clearly related to exposure to lindane. Exposure of humans occurs mainly via food, but this is decreasing. There may also be exposure from its use in public health and as a wood preservative. In the absence of genotoxicity and on the basis of the weight of the evidence from the studies of carcinogenicity, JMPR has concluded that Lindane is not likely to pose a carcinogenic risk to humans. Further, in an epidemiological study designed to assess the potential association between breast cancer and exposure to chlorinated pesticides, no correlation with Lindane was found.

Sampling could be proceed by sorption tubes. Extraction is done with different organic solvents. It is typically measured by Gas chromatography with electron capture detector (GC-ECD).

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