A-endosulfan

This study assesses the uptake of persistent organic pollutants (a-Endosulfan, P-Endosulfan and Endosulfan sulphate) from lettuce. The lettuce plants were grown on compost that had previously been contaminated at 10 and 50 J.g/g. 

Figure 13.19 Chromatograms obtained by on-line SPE-GC-MS(SIM) of (a) 10 ml of tap water spiked with pesticides at levels of 0.1 ng 1 (b) 10 ml of a sample of unspiked tap water. Peak identification foi (a) is as follows 1, molinate 2, a-HCH 3, dimethoate 4, simazine 5, ati azine 6, y-HCH 7, S-HCH 8, heptachloi 9, ametiyn 10, prometiyn 11, fen-itrothion 12, aldrin 13, malatliion 14, endo-heptachlor 15, a-endosulfan 16, teti achlor-vinphos 17, dieldrin. Reprinted from Journal of Chromatography, A 818, E. Pocumll et al., On-line coupling of solid-phase exti action to gas cliromatography with mass specti ometiic detection to determine pesticides in water , pp. 85-93, copyright 1998, with permission from Elsevier Science.

Chemical Identity of a-Endosulfan 3-3 Chemical Identity of [3-Endosulfan... 

Technical-grade endosulfan contains at least 94% a-endosulfan and (3-endosulfan. The a- and (3-isomers are present in the ratio of 7 3, respectively. The majority of the studies discussed below used technical-grade endosulfan. However, a few examined the effects of the pure a- and (3-isomers. Endosulfan sulfate is a reaction product found in technical-grade endosulfan as a result of oxidation, biotransformation, or photolysis. There is very little difference in toxicity between endosulfan and its metabolite, endosulfan sulfate. However, the a-isomer has been shown to be about three times as toxic as the P-isomer of endosulfan. 

The concentration of a- and P-endosulfan in the urine of a pest control worker who wore protective equipment peaked at 0.2 days (approximately 5 hours) after completing a 25-minute application of endosulfan in a greenhouse, declined to control levels by about 1.5 days postexposure, and remained at levels comparable to controls until the end of sampling at 3-days postexposure (Arrebola et al. 1999). Assuming first-order elimination, the urinary elimination half-Ufe was estimated to be 0.94 days for a-endosulfan and 1.16 days for p-endosulfan no endosulfan metabolite was detected in any urine sample. 

Gavage dosing of male and female rats with endosulfan (65.3% a-endosulfan, 33.7% P-endosulfan) for 30 days resulted in a greater accumulation of endosulfan in fatty tissue from females than males (Dikshith et al. 1984). The authors speculated that the difference between males and females was a function of more rapid excretion of endosulfan by males than females, and that this could account for the higher sensitivity of female rats to endosulfan toxicity. However, excretion of endosulfan and its metabolites was not directly measured in this study therefore, alternative explanations for the differences in residue content and toxicity caimot be discounted. 

Endosulfan and metabolites were observed in the urine of workers who had prepared and applied endosulfan for 2-5 hours either 1 day or 1 week prior to sampling, without using protective clothing or face mask (thus, exposure was probably both dermal and inhalation) (Vidal et al. 1998). Unchanged a-and P-endosulfan and endosulfan ether were the predominant chemicals excreted 1 day following exposure. One week after exposure, a-endosulfan was detected in urine of four of five workers, but P-endosulfan was detected in only one of five samples and endosulfan ether was not detected at all. Endosulfan sulfate was detected in only one of five samples at 1 week after exposure and in none of the four samples at 1 day postexposure. Endosulfan lactone was detected in one of four and one of five samples at 1 day and 1 week after exposure, respectively. 

Information is available regarding excretion of endosulfan and metabolites in humans. Blanco-Coronado et al. (1992) measured total endosulfan in the urine of poisoned individuals shortly after poisoning occurred. However, it could not be ascertained whether the urine was a major or minor excretion route. a-Endosulfan, P-endosulfan, and/or metabolites were present in the urine of humans after intentional oral exposure (Boerebomm et al. 1998) and after occupational exposure either with (Arrebola et al. 1999) or without (Vidal et al. 1998) protective clothing. 

Technical-grade endosulfan contains at least 94% of two pure isomers, a- and P-endosulfan (Maier-Bode 1968 NRCC 1975). The a- and p-isomers of endosulfan are present in the ratio of 7 3, respectively. Technical-grade endosulfan may also contain up to 2% endosulfan alcohol and 1% endosulfan ether. Endosulfan sulfate is a reaction product found in technical endosulfan it is also found in the environment due to photolysis and in organisms as a result of oxidation by biotransformation (EPA 1979 Coleman and Dolinger 1982). The chemical formula, structure, synonyms, and identification numbers for endosulfan, a-endosulfan, p-endosulfan, and endosulfan sulfate are listed in Tables 3-1, 3-2, 3-3, and 3-4, respectively. 

Important physical and chemical properties of endosulfan, a-endosulfan, p-endosulfan, and endosulfan sulfate are listed in Tables 3-5, 3-6, 3-7, and 3-8, respectively. It should be noted that P-endosulfan is slowly converted to a-endosulfan (Hapeman et al. 1997 Rice et al. 1997). 

Endosulfan does not bioaccumulate to high concentrations in terrestrial or aquatic ecosystems. In aquatic ecosystems, residue levels in fish generally peak within 7 days to 2 weeks of continuous exposure to endosulfan. Maximum bioconcentration factors (BCFs) are usually less than 3,000, and residues are eliminated within 2 weeks of transfer to clean water (NRCC 1975). A maximum BCE of 600 was reported for a-endosulfan in mussel tissue (Ernst 1977). In a similar study, endosulfan, isomers not specified, had a measured BCE of 22.5 in mussel tissue (Roberts 1972). Tissue concentrations of a-endosulfan fell rapidly upon transfer of the organisms to fresh seawater for example, a depuration half-life of 34 hours (Ernst 1977). Higher BCFs were reported for whole-body and edible tissues of striped mullet (maximum BCF=2,755) after 28 days of exposure to endosulfan in seawater (Schimmel et al. 1977). However, tissue concentrations decreased to undetectable levels 48 hours after the organisms were transferred to uncontaminated seawater. Similarly, a BCE of 2,650 was obtained for zebra fish exposed to 0.3 pg/L of endosulfan for 21 days in a flow-through aquarium (Toledo and Jonsson 1992). It was noted that endosulfan depuration by fish was rapid, with approximately 81% total endosulfan eliminated within 120 hours when the fish were placed in a tank of water containing no endosulfan. 

Endosulfan undergoes hydrolysis to endosulfan diol in surface water and groundwater. The rate of hydrolysis is influenced by pH. Half-life values reported in the literature vary somewhat. The chemical degradation of a- and P-endosulfan was studied under both anaerobic and aerobic environments. Under aerobic conditions, both hydrolysis and oxidation of endosulfan can occur, while under anaerobic conditions, only hydrolysis can occur. The hydrolytic half-lives for a- and P-endosulfan under anaerobic conditions at pH 7 were 35 and 37 days, respectively (Greve and Wit 1971). At pH 5.5 the half-lives were 151 and 187 days, respectively. Under aerobic conditions, the half-lives decreased. At pH 7, the half-lives of the chemical degradation (hydrolysis and oxidation) of both a- and P-endosulfan were 23 and 25 days, respectively, while at pH 5, the half-lives were 54 and 51 days, respectively. At T=20 and pHs of 5.5 and 8.0, the half-lives of a-endosulfan in distilled water were 11.3 and 5.3 days. 

Rainfall samples collected in the Great Lakes area of Canada in 1976 and 1977 contained mean concentrations of 1-2 ng/L (parts per trillion) a-endosulfan and 4—5 ng/L P-endosulfan. Endosulfan was detected in spring and summer rainfall samples but not in samples collected during the fall and winter (Strachan et al. 1980). a-Endosulfan has also been detected in snowpack samples obtained from widely distributed sites in the Canadian Arctic. Endosulfan concentrations in samples collected in the spring of 1986 ranged from 0.1 to 1.34 ng/L (Gregor and Gummer 1989). 

Rain samples collected from around the Great Lakes contained both a- and P-endosulfan (Strachan and Huneault 1979). Mean concentrations of a-endosulfan in rain samples from the Great Lakes ranged from 0.1 ng/L (n=13) to 3.8 ng/L (n=16). Mean concentrations of P-endosulfan in rain samples ranged from 1 (n=14) to 12 ng/L (n=16). The endosulfans were not found to any significant extent in snow-core samples (Strachan and Huneault 1979). Detection limits were not reported. 

In Hsinchu, Taiwan, the dietary intake of a- and P-endosulfan was studied from June 1996 to April 1997 (Doong and Lee 1999). p-Endosulfan was not detected in any of the 14 different foods studied, including fruits, meats, seafood, and cereal, and a-endosulfan, by contrast, was found in 78 of 149 samples at an average concentration of 2.76 ng/g wet weight. Based on the average Taiwanese diet, the estimated daily intake of a-endosulfan was 6.24x10 " mg body weight/day. 

Of the 91 samples of breast milk analyzed, only 2 had detectable quantities of endosulfan (concentrations not specified). In another study, the transfer of endosulfan and its metabolites were studied in breast milk of lactafing goats (Indraningsih et al. 1993). Endosulfan residues in milk of goats administered a daily dose of 1 mg/kg for 28 days reached 0.02 mg/kg on day 1. However, by day 8, no residues or metabolites could be detected. Likewise, no endosulfan residues could be detected in the tissues of kids except for a-endosulfan in the liver at a concentration of 0.0011 mg/kg. Analysis of milk from cows... 

GC/MS has been employed by Demeter et al. (1978) to quantitatively detect low-ppb levels of a- and P-endosulfan in human serum, urine, and liver. This technique could not separate a- and P-isomers, and limited sensitivity confined its use to toxicological analysis following exposures to high levels of endosulfan. More recently, Le Bel and Williams (1986) and Williams et al. (1988) employed GC/MS to confirm qualitatively the presence of a-endosulfan in adipose tissue previously analyzed quantitatively by GC/ECD. These studies indicate that GC/MS is not as sensitive as GC/ECD. Mariani et al. (1995) have used GC in conjunction with negative ion chemical ionization mass spectrometry to determine alpha- and beta-endosulfan in plasma and brain samples with limits of detection reported to be 5 ppb in each matrix. Details of commonly used analytical methods for several types of biological media are presented in Table 6-1. 

GC/ECD and GC/MS (EPA Method 608) are the methods recommended for determining a-endosulfan, (3-endosulfan, and endosulfan sulfate in municipal and industrial discharges (EPA 1991a). Sample clean-... 

Burgoyne TW, Hites RA. 1993. Effects of temperature and wind direction on the atmospheric concentrations of a-endosulfan. Environ Sci Technol 27(5) 910-914. 

Hoechst. 1985 a. Endosulfan-active ingredient technical (Code HOE 02671 OIID970003) 13-week toxicity study in rats followed by a 4-week withdrawal period, conducted at Huntingdon Research Center, England. Hoechst Aktiengesellschaft, Frankfurt, West Germany. Unpublished study, [unpublished study]... 

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