Endosulfan has been found in at least 143 of the 1416 National Priorities List sites
identified by the EPA [9]. Although not easily dissolved in water, when released to
water, endosulfan isomers hydrolyze readily in alkaline conditions and more slowly
in acidic conditions. Endosulfan has been detected at levels of 0.2–0.8μg/L in
groundwater, surface water, rain, snow, and sediment samples. Large amounts of
endosulfan can be found in surface water near areas of application. The USEPA
recommends that the amount of endosulfan in lakes, rivers, and streams should not
be more than 74 ppb [9]. Humans can become exposed to endosulfan by drinking
water contaminated with it.
3.1.3 Methoxychlor
Methoxychlor is an organochlorine insecticide that is effective against a wide range
of pests encountered in agriculture, households, and ornamental plants. It is registered for use on fruits, vegetables, and forage crops. The use of methoxychlor has
increased significantly since DDT was banned in 1972 [9]. It is similar in structure to
DDT, but it has a relatively low toxicity and relatively low persistence in biological
systems. Methoxychlor is not highly soluble in water. Methoxychlor is highly toxic
to fish and aquatic invertebrates. Levels of methoxychlor can accumulate in algae,
bacteria, snails, clams, and some fish, but it is usually transformed into other substances and rapidly released from their bodies. The most probable routes of exposure
for humans are inhalation or dermal contact during home use and ingestion of food
or drinking water contaminated with methoxychlor. Short-term exposure above the
MCL causes central nervous system depression, diarrhea, and damage to liver,
kidney, and heart tissue. Evidence suggests that high doses of technical methoxychlor or its metabolites may have estrogenic effects.
The risk of human exposure via groundwater should be slight, but it may be
greater if application rates are very high or if the water table is very shallow. At
present the strongest evidence of endocrine effects due to methoxychlor is taken
from laboratory studies in which the relatively low dose of 0.5μg/kg/d caused
reduced fertility in mice [16, 17].
In an USEPA pilot groundwater survey, methoxychlor was found in a number of
wells in New Jersey and at extremely low concentrations in water from the Niagara
River, the James River, and an unnamed Lake Michigan tributary [9]. Methoxychlor
will most likely reach surface waters via runoff. Methoxychlor was detected in
drinking water supplies in rural South Carolina. USEPA set a limit of methoxychlor
in drinking water at 0.04 mg/L (see Table 4.2). USEPA advises that children should
not drink water containing more than 0.05 mg/L for more than one day and that
adults should not drink water containing more than 0.2 mg/L for longer periods of
time [9].
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identified by the EPA [9]. Although not easily dissolved in water, when released to
water, endosulfan isomers hydrolyze readily in alkaline conditions and more slowly
in acidic conditions. Endosulfan has been detected at levels of 0.2–0.8μg/L in
groundwater, surface water, rain, snow, and sediment samples. Large amounts of
endosulfan can be found in surface water near areas of application. The USEPA
recommends that the amount of endosulfan in lakes, rivers, and streams should not
be more than 74 ppb [9]. Humans can become exposed to endosulfan by drinking
water contaminated with it.
3.1.3 Methoxychlor
Methoxychlor is an organochlorine insecticide that is effective against a wide range
of pests encountered in agriculture, households, and ornamental plants. It is registered for use on fruits, vegetables, and forage crops. The use of methoxychlor has
increased significantly since DDT was banned in 1972 [9]. It is similar in structure to
DDT, but it has a relatively low toxicity and relatively low persistence in biological
systems. Methoxychlor is not highly soluble in water. Methoxychlor is highly toxic
to fish and aquatic invertebrates. Levels of methoxychlor can accumulate in algae,
bacteria, snails, clams, and some fish, but it is usually transformed into other substances and rapidly released from their bodies. The most probable routes of exposure
for humans are inhalation or dermal contact during home use and ingestion of food
or drinking water contaminated with methoxychlor. Short-term exposure above the
MCL causes central nervous system depression, diarrhea, and damage to liver,
kidney, and heart tissue. Evidence suggests that high doses of technical methoxychlor or its metabolites may have estrogenic effects.
The risk of human exposure via groundwater should be slight, but it may be
greater if application rates are very high or if the water table is very shallow. At
present the strongest evidence of endocrine effects due to methoxychlor is taken
from laboratory studies in which the relatively low dose of 0.5μg/kg/d caused
reduced fertility in mice [16, 17].
In an USEPA pilot groundwater survey, methoxychlor was found in a number of
wells in New Jersey and at extremely low concentrations in water from the Niagara
River, the James River, and an unnamed Lake Michigan tributary [9]. Methoxychlor
will most likely reach surface waters via runoff. Methoxychlor was detected in
drinking water supplies in rural South Carolina. USEPA set a limit of methoxychlor
in drinking water at 0.04 mg/L (see Table 4.2). USEPA advises that children should
not drink water containing more than 0.05 mg/L for more than one day and that
adults should not drink water containing more than 0.2 mg/L for longer periods of
time [9].
178
N. K. Shammas et al.