Page 116 - Environmental Control in Petroleum Engineering

The Impact of Drilling and Production Operations 103

disorders, and damage to the liver, heart, nerves, and kidneys. Expo-
sure to arsenic compounds in drugs, food, and water have been
causally associated with the development of cancer, primarily of the
skin and lungs, although a direct connection has never been proven,
Low doses stimulates plant growth. Arsenic may impact embryo and
larval states of fish and benthic invertebrates.

Barium: Barium ion is a muscle poison causing stimulation and then
paralysis. Soluble barium salts are skin and mucous membrane irri-
tants. In animals, BaO and BaCO 3 cause paralysis. Ba is also poisonous
to most plants. The barium ion is a physical antagonist of potassium,
interfering with the vital cellular use of potassium.
Although elemental barium is extremely toxic, the barium com-
pounds encountered during drilling and production activities are
relatively nontoxic. The most commonly found form of barium is
barium sulfate, which is insoluble in geochemical conditions and is
not taken up by plants. Barium sulfate is not absorbed by animals or
humans if ingested. It is commonly used internally for medical applica-
tions using X-ray diagnostics. Barium carbonate is moderately soluble
and is more toxic, but is rarely used.

Cadmium: Excess exposure to cadmium can lead to renal failure,
anemia, bone fractures, kidney stones, osteomalacia, retarded growth,
pulmonary emphysema, and pain in the back and joints. Cadmium has
been implicated in respiratory tract cancer. There is little evidence of
carcinogenicity for exposure by ingestion. Organometallic derivatives
may be concentrated in lipid tissues and cause chromosome damage.
Cadmium interferes with the metabolism of zinc and copper in humans,

Chromium: The toxicity of chromium depends primarily on its chemi-
cal valence state and its concentration. Chromium is considered to be
an essential element in humans at low levels. At higher concentrations,
hexavalent chromium can be highly toxic, while trivalent chromium
is relatively nontoxic. Hexavalent chromium can cause severe irritation
to the respiratory system, asthma, and kidney damage. Some hexa-
valent chromium compounds are carcinogenic. Prolonged inhalation
of trivalent chromium may cause scarring of the lungs. Other effects
of chronic exposure at high levels include lung cancer, dermatitis,
alceration of the skin, chronic catarrh, and emphysema. However,