Page 108 - Environmental Control in Petroleum Engineering

The Impact of Drilling and Production Operations 95

be weight loss from loss of appetite, muscular weakness and cramps,
sporadic electroencephalography irregularities, and possible liver and
renal damage.
Exposure of eyes and skin to hydrocarbons may result in irritation,
mechanical or chemical damage to eye tissue, or dermatitis. Long-term
exposure to vacuum distillates has caused skin cancer in animals.
Exposure to petrochemicals, particularly polyaromatic hydrocarbons,
increases susceptibility to skin infections, including skin cancer when
there is simultaneous exposure to sunlight (Burnham and Bey, 1991;
Burnham and Rahman, 1992).
One potential source of hydrocarbon exposure to humans is inges-
tion of hydrocarbon-contaminated food, particularly seafood. Studies
have shown that most organisms cleanse themselves of hydrocarbons
within a matter of weeks after being removed from the source of
contamination. This cleansing time, however, depends upon the con-
taminated organism.
The exposure levels of humans to polyaromatic hydrocarbons from
crude oil may be lower than those from other, more common sources
like grilled food and combustion products, or from naturally occurring
sources like coffee, grains, and vegetables (American Petroleum
Institute, 1978).
Suggested standards for human exposure to petroleum hydrocarbons
varies with the specific hydrocarbon, but ranges between 25 and 430
ppm (National Research Council, 1985). Permitted occupational expo-
sure levels to benzene are on the order 10 ppm, but vary with the
prevailing regulations.

Impact on Plant Growth

Hydrocarbons also impact plant growth when released on land.
Levels of oil and grease above a few percent in soils (by weight) have
shown degradation of plant growth. Levels below a few percent have
shown an actual enhancement of some crop growth. Recovery of an
exposed site after a one-time hydrocarbon release usually occurs after
a few months (Deuel, 1990). A level of 1% oil and grease is recom-
mended as a practical threshold where the hydrocarbons become
detrimental to plant life (American Petroleum Institute, 1989b).
Airborne hydrocarbons emitted during blowouts can also impact
plant growth around the wellhead. Long-term growth rate reductions