the third most prevalent waste in the industrial discharges—standards for
short—term exposures
have been set by the Public Health Service in addition
to the mandatory limit of 0.05 mg/l considered physiologically safe over a
lifetime. For a few weeks, as much as 2—4 mg/l of lead is not considered un—
safe, although this same concentration borders on harmful if it continues for
three months. Lead is toxic if taken in for several weeks at concentrations of
8—10 mg/l, and a concentration of 15 mg/l over the same period may be le—
thal—although the lethal concentration is not known with certainty.
How do 3700 pounds of lead dumped into the river per day from a single
plant relate to these standards? This is difcult to say, since the EPA study did
not test drinking water for lead. However, at the point where the efuent of
one chemical company was dumped into the river, samples collected on three
different days were found to contain 1.2 mg/l of lead on a day when 218
pounds of lead were dumped, 2.8 mg/l on a day when 485 pounds were
dumped, and 4.8 mg/l on a day When 890 pounds were dumped. Dumping
3700 pounds of lead in a single day could therefore produce & concentration
of lead in the efuent of as much as 20 mg/l. How much of this lead is still in
the water when it ows out of kitchen taps in Baton Rouge, New Orleans, and
the small towns along the Mississippi is one important question, but some of
the lead could also reach humans via food chains.
Lead ingested from air, food, or water can accumulate in the body and
cause serious damage to the kidney, liver, or brain, and to the reproductive
and central nervous systems. At subtoxic levels, lead interferes with the func—
tioning of red blood cells; at toxic levels, red blood cells may be destroyed.
Children in particular are affected by lead poisoning—mental retardation, for
example, is a common result of lead poisoning in children [7].
PHS standards for cadmium limit the concentration to 0.01 mg/l. A vari—
ety of health effects have been attributed to cadmiurn ingestion. Hyperten—
sion is correlated with increased retention of cadmium in the kidneys, and
cadrnium ingestion may cause cramps, nausea, vomiting, and diarrhea. The
metal is perhaps most infamous as the cause of itai—itai disease, the hyperex—
cretion of calcium which leads to softening of the bones [8]. Cadmium was
found in quantities greater than ve pounds per day in eight different waste
discharges in the lower Mississippi, but concentrations of cadmium in water
samples were not reported.
Because of their known toxicity, the Public Health Service has set stand—
ards for other heavy metals found in industrial waste efuent in the Mis—
sissippi. These include chromium, copper, zinc, aresnic, and mercury, but
again, as with cadmium, the data in the report are insufficient to relate the
amounts found to the standards. (However, recall that the PHS study found
concentrations of these heavy metals in excess of the standards.)
'
The same problem exists in interpreting the report’s nding that 17 plants
discharged ten pounds or more of phenols per day. Phenols impart an objec—
tionable odor and taste to water, and may have been responsible, at least in
part, for the “chemical” odor and taste in drinking water that triggered the
Lower Mississippi study. The Public Health Service set a limit of 0.001 mg/ l
Chemical Contamination
151
short—term exposures
have been set by the Public Health Service in addition
to the mandatory limit of 0.05 mg/l considered physiologically safe over a
lifetime. For a few weeks, as much as 2—4 mg/l of lead is not considered un—
safe, although this same concentration borders on harmful if it continues for
three months. Lead is toxic if taken in for several weeks at concentrations of
8—10 mg/l, and a concentration of 15 mg/l over the same period may be le—
thal—although the lethal concentration is not known with certainty.
How do 3700 pounds of lead dumped into the river per day from a single
plant relate to these standards? This is difcult to say, since the EPA study did
not test drinking water for lead. However, at the point where the efuent of
one chemical company was dumped into the river, samples collected on three
different days were found to contain 1.2 mg/l of lead on a day when 218
pounds of lead were dumped, 2.8 mg/l on a day when 485 pounds were
dumped, and 4.8 mg/l on a day When 890 pounds were dumped. Dumping
3700 pounds of lead in a single day could therefore produce & concentration
of lead in the efuent of as much as 20 mg/l. How much of this lead is still in
the water when it ows out of kitchen taps in Baton Rouge, New Orleans, and
the small towns along the Mississippi is one important question, but some of
the lead could also reach humans via food chains.
Lead ingested from air, food, or water can accumulate in the body and
cause serious damage to the kidney, liver, or brain, and to the reproductive
and central nervous systems. At subtoxic levels, lead interferes with the func—
tioning of red blood cells; at toxic levels, red blood cells may be destroyed.
Children in particular are affected by lead poisoning—mental retardation, for
example, is a common result of lead poisoning in children [7].
PHS standards for cadmium limit the concentration to 0.01 mg/l. A vari—
ety of health effects have been attributed to cadmiurn ingestion. Hyperten—
sion is correlated with increased retention of cadmium in the kidneys, and
cadrnium ingestion may cause cramps, nausea, vomiting, and diarrhea. The
metal is perhaps most infamous as the cause of itai—itai disease, the hyperex—
cretion of calcium which leads to softening of the bones [8]. Cadmium was
found in quantities greater than ve pounds per day in eight different waste
discharges in the lower Mississippi, but concentrations of cadmium in water
samples were not reported.
Because of their known toxicity, the Public Health Service has set stand—
ards for other heavy metals found in industrial waste efuent in the Mis—
sissippi. These include chromium, copper, zinc, aresnic, and mercury, but
again, as with cadmium, the data in the report are insufficient to relate the
amounts found to the standards. (However, recall that the PHS study found
concentrations of these heavy metals in excess of the standards.)
'
The same problem exists in interpreting the report’s nding that 17 plants
discharged ten pounds or more of phenols per day. Phenols impart an objec—
tionable odor and taste to water, and may have been responsible, at least in
part, for the “chemical” odor and taste in drinking water that triggered the
Lower Mississippi study. The Public Health Service set a limit of 0.001 mg/ l
Chemical Contamination
151