Page 117 - Environmental Control in Petroleum Engineering

104 Environmental Control in Petroleum Engineering

virtually all chromium found in the drilling and production industry
is in the low solubility, low toxicity trivalent form.
Bioassays on freshwater organisms for trivalent chromium at con-
centrations around 1.0 mg/1 yielded a mixture of no effects to mixed
sublethal effects after exposures of up to three months. A three-week
LC 50 value for Daphnia magna (freshwater shrimp) was reported as
2.0 mg/1. No significant mortalities were observed on Neanthes arena-
ceodentata (marine polychaetes) for three-week exposures to trivalent
chromium at concentrations up to 12.5 mg/1. Bioassays on marine
organisms for trivalent chromium yielded 96-hr LC 50 values of 53 mg/1
on juvenile fish and 24-hr LC 100 values (100% mortality) of around
50 mg/1 on invertebrates. For comparison, 96-hr LC 50 values on the
same invertebrate species for hexavalent chromium was about 3.0 mg/1
(American Petroleum Institute, 1981b),

Cobalt: This metal is essential to blue-green algae and some bacteria,
fungi, and green algae, but there is little evidence of its essentiality
to higher plants. Normal human intake is 0.002 mg/day, with toxic
levels at 500 mg/day. Cobalt metal dust is more toxic than salts in
inhalation. Higher concentrations cause dermatitis, heart and gastro-
intestinal tract disorders, and liver and kidney damage.

Copper: Inhalation of dust causes lung and gastrointestinal disturbances.
It affects erythrocytes and the liver and irritates skin and mucous membranes,

Lead: Prolonged exposure induces toxic responses in the hemotologi-
cal, neurological, and renal systems, leading to brain damage, convul-
sions, behavioral disorders, and death. There is some evidence that
some soluble lead salts are carcinogenic in some animals, but there
is little evidence of their carcinogenicity in humans. Organometallic
derivatives may be concentrated in lipid tissues and cause chromosome
damage. Some plants show retarded growth at 10 ppm. Subtoxic
effects have been observed in microflora at 0.1 ppm.

Manganese: Pathological effects on nerve cells and the liver have
been reported.

Mercury: Chronic exposure to mercury causes weakness, fatigue,
anorexia, and disturbances of gastrointestinal functions. Following high