Environmental Fate
Soil. Metabolites of endosulfan identified in soils included endosulfandiol, endosulfanhydroxy
ether, endosulfan lactone and endosulfan sulfate (Martens, 1977; Dreher and
Podratzki, 1988). These compounds, including endosulfan ether, were also reported as
metabolites identified in aquatic systems (Day, 1991). In aerobic soils, b-endosulfan is
converted to the corresponding alcohol and ether (Perscheid et al., 1973). Endosulfan
sulfate was the major biodegradation product in soils under aerobic, anaerobic and flooded
conditions (Martens, 1977). In flooded soils, endolactone was detected only once whereas
endodiol and endohydroxy ether were identified in all soils under these conditions. Under
anaerobic conditions, endodiol formed in low amounts in two soils (Martens, 1977).
Indigenous microorganisms obtained from a sandy loam degraded b-endosulfan to
endosulfan diol. This diol was converted to endosulfan a-hydroxy ether and trace amounts
of endosulfan ether and both were degraded to endosulfan lactone (Miles and Moy, 1979).
Plant. In addition, endosulfan sulfate was formed when endosulfan was translocated
from the leaves to roots in both bean and sugar beet plants (Beard and Ware, 1969). In
tobacco leaves, b-endosulfan hydrolyzed into endosulfandiol (Chopra and Mahfouz, 1977).
Stewart and Cairns (1974) reported the metabolite endosulfan sulfate was identified in
potato peels and pulp at concentrations of 0.3 and 0.03 ppm, respectively. They also
reported that the half-life for the oxidative conversion of b-endosulfan to endosulfan sulfate
was 800 days.
In carnation plants, the half-lives of b-endosulfan stored under four different conditions,
non-washed and exposed to open air, washed and exposed to open air, non-washed
and placed in an enclosed container and under greenhouse conditions were 23.40, 12.64,
37.42 and 7.62 days, respectively (Ceron et al., 1995).
Surface Water. Endosulfan sulfate was also identified as a metabolite in a survey of
11 agricultural watersheds located in southern Ontario, Canada (Frank et al., 1982). When
endosulfan (a- and b- isomers, 10 mg/L) was added to Little Miami River water, sealed
and exposed to sunlight and UV light for 1 week, a degradation yield of 70% was observed.
After two and four weeks, 95% and 100% of the applied amount degraded. The major
degradation product was identified as endosulfan alcohol by IR spectrometry (Eichelberger
and Lichtenberg, 1971).
Photolytic. Thin films of endosulfan on glass and irradiated by UV light (l >300 nm)
produced endosulfan diol with minor amounts of endosulfan ether, lactone, a-hydroxyether
and other unidentified compounds (Archer et al., 1972). Gaseous b-endosulfan subjected
to UV light (l >300 nm) produced endosulfan ether, endosulfan diol, endosulfan sulfate,
endosulfan lactone, a-endosulfan and a dechlorinated ether (Schumacher et al., 1974).
Irradiation of b-endosulfan in n-hexane by UV light produced the photoisomer a-endosulfan
(Putnam et al., 1975). When an aqueous solution containing endosulfan was photooxidized
by UV light at 90–95°C, 25, 50 and 75% degraded to carbon dioxide after 5.0, 9.5
and 31.0 hours, respectively (Knoevenagel and Himmelreich, 1976).
Chemical/Physical. Endosulfan detected in Little Miami River, OH was readily hydrolyzed
to a compound tentatively identified as endosulfan diol (Eichelberger and Lichtenberg,
1971). Sulfuric acid is also an end product of hydrolysis (Kollig, 1993). The hydrolysis
half-lives at pH values (temperature) of 3.32 (87.0°C), 6.89 (68.0°C) and 8.69 (38.0°C)
were calculated to be 2.7, 0.07 and 0.04 days, respectively (Ellington et al., 1988). Greve
and Wit (1971) reported the hydrolysis half-lives of b-endosulfan at 20°C and pH values
of 7 and 5.5 were 37 and 187 days, respectively.
