7 no 3, 1999
WorkSafe Guidelines for Building Cavity Dust
By Elizabeth O'Brien, National Coordinator, The LEAD Group Inc.
Following from the last edition of LEAD Action News, I tried to research the possible health effects of exposure to ceiling dust and other building cavity dust, and to find out what, if any, guidelines could be applied to handling the dust. The Safe Work Australia (previously WorkSafe) website contains an overwhelming amount of information on Air Toxics at Work. To piece together all the relevant standards for working in building cavity dust, one would have to, at the minimum, check out the following sections:-
AIRBORNE PARTICULATES: Building cavity dust does not have an assigned exposure standard. The advice is, "it should not be assumed that this indicates that these unlisted dusts do not represent a hazard to health."
HAZARDOUS SUBSTANCES: In this section the exposure standards are given for about 26 of the elements found to be in ceiling dust by Jeff Davis (see article on page one of this newsletter), but mostly as compounds. The section includes the following excerpts:
INDEPENDENT EFFECTS: "Where there is clear toxicological evidence to indicate that two or more contaminants have totally distinct mechanisms of effect on the body, then each substance may be separately evaluated against its appropriate exposure standard."
ADDITIVE EFFECTS: "When the body is exposed to two or more contaminants, an additive effect is obtained when contaminants have the same target organ or the same mechanism of action. In this situation, the total effect upon the body equals the sum of effects from the individual substances."
SYNERGISM AND POTENTIATION: "Sometimes the combined effect of multiple exposure is considerably greater than the sum of the effects from the individual components. This phenomenon can be one of synergism or potentiation. Synergism occurs when both chemicals have an effect individually and a more than additive effect when together. Potentiation is when one chemical has an effect but the second chemical does not but enhances the effect of the former chemical on combined exposure.
"Interaction effects may also occur in connection with exposure to entirely different environmental factors such as simultaneous exposure to chemical agents and physical factors, such as light, heat and noise... Smoking of tobacco is known to have a synergistic effect in combination with, for example, inhaled particulates.
"At present the understanding of interaction effects is incomplete. The knowledge that such effects can occur is reason to maintain the concentrations of individual substances as low as is practicable under complex exposure conditions."
FIBRES: since the ceiling cavity can contain various types of insulation including asbestos insulation around hot water heaters, the following excerpts are relevant:-
ASBESTOS: "The average fibre concentration of the air breathed by a worker throughout a working shift...should not exceed...0.1 fibres per mL of air (TWA [time weighted average] Exposure Standard) [for] any mixture of [the different types of] asbestos, or where the composition is unknown."
SYNTHETIC MINERAL FIBRES: "For respirable fibres, the National Commission has adopted a TWA exposure standard of 0.5 fibres per mL of air be applied to synthetic mineral fibres (ceramic fibres, glass fibre and rock wool).
"For non-respirable fibres, in situations where almost all the airborne material is fibrous, a secondary, yet complementary, TWA exposure standard of 2 mg/m3 (inspirable dust) is proposed."
PESTICIDES: If exposure to pesticides is suspected, blood samples can be analysed to determine the extent of exposure.
When "building cavity dust" is an actual listed item in all these government guidelines, the Australian Dust Removalists Association will have had success!
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Updated 09 October 2011