Environmental Engineering Reference
In-Depth Information
EPA has established a Maximum Contaminant Level (MCL) of0.005
milligrams per liter (mg/L) for cadmium in drinking water. Drinking water
levels which are considered "safe" for short-term exposures are: 0.04 mg/L for
a 10-kg (22 lb.) child consuming 1 liter of water per day for one- to ten-day
exposures, and 0.005 mg/L for a longer term (up to 7 years) exposure
(USEPA, 1975).
The Agency has found cadmium to potentially cause a variety of effects
from acute exposures including: nausea, vomiting, diarrhea, muscle cramps,
salivation, sensory disturbances, liver injury, convulsions, shock and renal
failure. Cadmium has the chronic potential to cause kidney, liver, bone and
blood damage from long term exposure at levels above the MCL. There is
inadequate evidence to state whether or not cadmium has the potential to cause
cancer from lifetime exposure in drinking water.
Cadmium, a non-essential, non-beneficial, non-biodegradable element to
plants and animals and travels through the food chain. Since cadmium is a
metal, it does not break down and can build up over time in the environment in
various forms.
Cadmium waste is generated from both natural as well as anthropogenic
sources (Hayes, 2007).Of the various sources of water pollution, one of the
most important is industrial waste water directly entering into the aquatic
systems and has resulted in the transformation of lakes into sewage lagoons.
2.
S
OURCES AND
T
YPES OF
W
ASTE
The major sources of cadmium release into the environment by waste
streams are electroplating, smelting, alloy manufacturing, pigments, plastic,
batteries, mining and refining processes and industries (Malkoc and Nuhoglu,
2005; Guiqiu et al., 2008; Xiaomin et al., 2007). Cadmium also occurs as a
minor component in most zinc, lead and copper ores, in coal and other fossil
fuels, in shales and is released during volcanic action. These deposits can serve
as sources to pollute ground and surface waters, especially when in contact
with water having low total dissolved solids (TDS) and pH. Major industrial
releases of cadmium are due to waste streams and leaching of landfills, and
from a variety of operations that involve cadmium and/or zinc.
The cadmium so produced find waystoenterin to the three major
compartments of the environment - air, water and soil and there may be
considerable transfer between the three compartments after initial deposition.
Emissions in air are considered more mobile than those to water which in turn
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