Toxic Pollution 151
conclusively. The limit set for aluminium dust in the air in the work environment is 15 mg/m 3 . Household use of aluminium has been deemed safe.
7.4.8 arsenic
Arsenic (As) is a non-metallic element widely occurring in the Earth’s
crust. It is dispersed in the air, water and soil, having resulted from erosion of rocks. In the environment it usually occurs in inorganic compounds
with oxygen, chlorine and sulphur, but it also forms organic compounds.
Inorganic compounds of arsenic are used in various industrial applications,
and organic compounds are used as components in pesticides, particularly
in the cultivation of cotton. Living organisms such as fish bioaccumulate
arsenic, but mostly in an organic form that is not particularly harmful. For
humans, its inorganic compounds are the most dangerous. In high concentrations arsenic is lethal. Ingestion of lower concentrations causes nausea
and damage to the blood. Inhalation causes irritation of the respiratory
system and contact causes irritation of the skin. Long-term exposure to low
concentrations of arsenic may cause skin lesions. It has also been listed as
a carcinogenic substance. The US EPA has set a very low limit for drinking
water, and has banned many of its uses in pesticides. A limit of 10 µg/m 3
has also been set for air in the work environment.
7.4.9 Fluorine compounds
The toxicity of fluorine compounds has been the subject of public debate
due to conflicting opinions on the advisability of artificial fluoridation of
drinking water in order to combat dental caries. Fluorine compounds are
accumulated in tissues and cause damage to plants, algae and animals.
Some plants and microorganisms synthesise toxic organic fluorine compounds. The borderline between dangerous and safe concentrations for
humans is not clear-cut, as is also the case with many other toxic materials.
Some people are more sensitive than others, and the toxic action of fluorine
compounds may be stronger in combination with other pollutants.
A rather wide variety of industrial activities leads to the disposal of fluorine compounds in the air and waters. Thus, during electrolytic production of aluminium, the cryolite (Na 3 AlF 6 ) used as a solvent for Al 2 O 3 is
in a molten state accompanied by substantial steam pressure. The result is
that in the absence of suitable prevention measures, substantial quantities of
fluorine compounds escape into the atmosphere, which may fall with rain
onto neighbouring land and cause significant damage to livestock farming.
Drinking water is fluoridated at a concentration of around 1 mg/L (as F).
There is no convincing evidence that such fluoridation is harmful. The limit
in drinking water has been set at 4 mg/L. Scientific documentation of the
conclusively. The limit set for aluminium dust in the air in the work environment is 15 mg/m 3 . Household use of aluminium has been deemed safe.
7.4.8 arsenic
Arsenic (As) is a non-metallic element widely occurring in the Earth’s
crust. It is dispersed in the air, water and soil, having resulted from erosion of rocks. In the environment it usually occurs in inorganic compounds
with oxygen, chlorine and sulphur, but it also forms organic compounds.
Inorganic compounds of arsenic are used in various industrial applications,
and organic compounds are used as components in pesticides, particularly
in the cultivation of cotton. Living organisms such as fish bioaccumulate
arsenic, but mostly in an organic form that is not particularly harmful. For
humans, its inorganic compounds are the most dangerous. In high concentrations arsenic is lethal. Ingestion of lower concentrations causes nausea
and damage to the blood. Inhalation causes irritation of the respiratory
system and contact causes irritation of the skin. Long-term exposure to low
concentrations of arsenic may cause skin lesions. It has also been listed as
a carcinogenic substance. The US EPA has set a very low limit for drinking
water, and has banned many of its uses in pesticides. A limit of 10 µg/m 3
has also been set for air in the work environment.
7.4.9 Fluorine compounds
The toxicity of fluorine compounds has been the subject of public debate
due to conflicting opinions on the advisability of artificial fluoridation of
drinking water in order to combat dental caries. Fluorine compounds are
accumulated in tissues and cause damage to plants, algae and animals.
Some plants and microorganisms synthesise toxic organic fluorine compounds. The borderline between dangerous and safe concentrations for
humans is not clear-cut, as is also the case with many other toxic materials.
Some people are more sensitive than others, and the toxic action of fluorine
compounds may be stronger in combination with other pollutants.
A rather wide variety of industrial activities leads to the disposal of fluorine compounds in the air and waters. Thus, during electrolytic production of aluminium, the cryolite (Na 3 AlF 6 ) used as a solvent for Al 2 O 3 is
in a molten state accompanied by substantial steam pressure. The result is
that in the absence of suitable prevention measures, substantial quantities of
fluorine compounds escape into the atmosphere, which may fall with rain
onto neighbouring land and cause significant damage to livestock farming.
Drinking water is fluoridated at a concentration of around 1 mg/L (as F).
There is no convincing evidence that such fluoridation is harmful. The limit
in drinking water has been set at 4 mg/L. Scientific documentation of the