ILO Convention on Asbestos Usage – ILO in 1986 unanimously adopted the Convention on the Safe Use of Asbestos. India is a signatory to this Convention and the entire organized sector of the Industry is strictly following the recommendations/guidelines of ILO. ILO guidelines have been suitably incorporated in the 15 standards laid down by the Bureau of Indian Standards (BIS) for the Asbestos Industry and also in the relevant section of Factories Act covering Occupational health of workers engaged in this Industry.
WHO 1998 Publication on “Chrysotile Asbestos – Environmental Health Criteria 203 - WHO in its publication on “Chrysotile Asbestos – Environmental Health Criteria 203 has recommended the following on controlled use and further research:
Para 10(d) – Page 144
“Control measures, including engineering controls and work practices, should be used in circumstances where occupational exposure to Chrysotile can occur. Data from industries where control technologies have been applied have demonstrated the feasibility of controlling exposure to levels generally below 0.5 f/ml. Personal protective equipment can further reduce individual exposure where engineering controls and work practices prove insufficient”.
Para 11 (a) – Page 145
“Research and guidance are needed concerning the economic and practical feasibility of substitution for chrysotile asbestos, as well as the use of engineering controls and work practices in developing countries for controlling asbestos exposure”.
WHO Guidelines on Drinking Water Quality - WHO in 1993 undertook an exercise to lay down the acceptable concentration of various chemicals in drinking water. While WHO has specified the concentration levels for Arsenic, Barium etc. they have concluded that “
there is no consistent evidence that ingested asbestos is hazardous to health and thus it was concluded that there was no need to establish a health-based guideline value for asbestos in drinking water.”
Relevant extract from WHO Publication of 1993 “Guidelines for drinking water quality” – Second Edition Volume I on acceptable values in respect of Asbestos and Barium are given for comparative study.
Asbestos - Asbestos is introduced into water by the dissolution of asbestos-containing minerals and ores as well as from industrial effluents, atmospheric pollution, and asbestos-cement pipes in the distribution system. Exfoliation of asbestos fibres from asbestos-cement pipes is related to the aggressiveness of the water supply. Limited data indicate that exposure to airborne asbestos released from tap water during showers or humidification is negligible.
There has been little 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 increased the incidence of tumours of the gastrointestinal tract.
There is, therefore, no consistent evidence that ingested asbestos is hazardous to health, and thus it was concluded that there was no need to establish a health-based guideline value for asbestos in drinking water .
Barium - Barium occurs as a number of compounds in the earth's crust and is used in a wide variety of industrial applications, but it is present in water primarily from natural sources. In general, good is the principal source of exposure to barium, however, in areas where barium concentrations in water are high, drinking water may contribute significantly to total intake. Intake from air is negligible.
Although an association between mortality from cardiovascular disease and the barium content of drinking water was reported in a ecological epidemiological study, these results were not confirmed in an analytical epidemiological study of the same population, more over, in a short-term study in a small number of volunteers, there was no consistent indication of adverse cardiovascular effects following exposure to barium at concentrations of upto 10mg/litre in water. There was, however, an increase in the systolic blood pressure of rats exposed to relatively low concentrations of barium in drinking water.
A guideline value of 0.7 mg/litre (rounded figure) was derived using the NOAEL of 7.3mg/litre from most sensitive epidemiological study conducted to date, in which there were no significant differences in blood pressure or the prevalence of cardiovascular disease between a population drinking water containing a mean barium concentration of 7.3 mg/litre and one ingesting water.
From above it will be noted that no health based guidelines value for asbestos in drinking water has been specified. The following extract of Ann 2 table (A2.3) to the Guidelines of drinking water quality is given below:
Table A2.3 – Chemicals not of health significance at concentration normally found in drinking water
| Chemical |
Remarks |
| Asbestos |
U |
| Silver |
U |
| Tin |
U |
U – It is unnecessary to recommend a health-based guideline value for these compounds because they are not hazardous to human health at concentrations normally found in drinking water.
