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This has reference to your recent visit to my office
regarding the above subject. We have the following points to offer
:
Potential hazard of asbestos-cement pipes is the
release of asbestos from such pipes. A WHO Task Group on
Asbestos and Other Natural Mineral Fibers concluded that “the studies
conducted to date provide little convincing evidence of an association
between asbestos in public water supplies and cancer induction.”
(Reference : International Programme on Chemical Safety, Environmental
Health Criteria No. 53 : Asbestos and Other Natural Mineral Fibers
, WHO Guidelines for Drinking -Water Quality reached the same conclusion
in 1991." The weight of evidence shows that ingested
asbestos is not hazardous to health."
As to ferro-cement pipes, a possible concern is
the release of iron from such pipes. Based on health considerations,
up to 2 mg/litre of iron can be tolerated in drinking-water. It
is unlikely that such a level would be reached through iron dissolution
from the pipes.
Asbestos is a known human carcinogen by the inhalation
route. Although well studied, there has been convincing evidence
of the carcinogenicity of ingested asbestos in epidemiological studies
of populations with drinking-water supplies, containing high concentrations
of asbestos. Moreover, in extensive studies in animal species, asbestos
has not consistently induced increases in the incidence of tumours
of the gastrointestinal tract. The weight of the evidence shows
that ingested asbestos is not hazardous to health, and, on this
basis, it is considered unnecessary to recommend a health-based
guideline value for asbestos in drinking-water.
Owing to the potential for the dissolution of the
cement and subsequent structural failures, A/C pipe should not be
used in areas where the water supply is aggressive.
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