QUESTION: Does dust from old wood with 0.85% Pb pose a health hazard?
12 Dec 2003, New South Wales Australia
I recently had a sample of wood shavings from an old door analysed for its total lead concentration. The laboratory reported the Pb content as 8,500 mg/kg.
Is this concentration high enough to suggest a lead-based paint is present on the door ? Also, and perhaps more importantly, could such a lead concentration pose a significant health hazard, if a person was exposed to dusts generated during sanding of the door ?
ANSWER: 15 Dec 2003
If you are asking whether the old door currently is coated with paint made from basic lead carbonate (the old definition of lead-based paint) then I would say no, because this paint is typically in the tens of percent lead concentration range. "Lead paint" is more recently defined in the Australian Standard AS4361.2 - 1998 Guide To Lead Paint Management - Part 2: Residential And Commercial Buildings, as containing more than 1% lead and people loosely apply the term "lead-based paint" to this definition, so since the wood shavings from the door contain 8,500 ppm or 0.85% lead, then the answer would still be no. However, in the USA, the term is clearly defined in legislation at half the Australian level:
"The HUD/EPA term “lead-based paint” addresses the layers of paint on an applicable surface having lead equal to or greater than 1.0 mg/cm2 or 0.5% by weight." [Reference: "Interpretive Guidance: The HUD Regulation On Controlling Lead-Based Paint Hazards In Housing Receiving Federal Assistance And Federally Owned Housing Being Sold (24 CFR Part 35)", by U.S. Department of Housing and Urban Development [HUD] Office of Healthy Homes and Lead Hazard Control, Washington, DC 20410, April 16, 2001]. Thus the lead content of the wood shavings is, under US legislation, above the criteria level of lead-based paint. Since you haven't mentioned that there was actually any paint on the wood shavings tested, my guess is that the wood shavings came from the surface of the door from which either lead paint has fallen off or been removed, especially removed by chemical stripping. Chemical stripping is known for it's ability to dissolve some of the lead from the paint in the stripper and then take that lead on into the wood fibre, leaving a door that appears not to be painted but which is in fact by US definition, going to pose a significant health hazard if dry sanded without respiratory protection for the operator and protection of the environment (eg via a vacuum extraction unit on the sander, plastic sheeting, plastic enclosure etc).
By comparison, Australia has totally lax regulations, eg NSW Consolidated OH&S Regulations only covers "machine sanding or buffing of surfaces coated with paint containing more than one per cent by dry weight of lead" and "lead risk work means a lead process or a work activity or sequence of activities at a specific area within a place of work in which the blood lead level of an employee might reasonably be expected to rise or does rise above 1.45 µmol/L (30 µg/dL)". [Reference: NSW OHS Regulation 2001 With Margin Notes, www.legislation.nsw.gov.au/maintop/view/inforce/subordleg+648+2001+cd+0+N
So despite the National Health and Medical Research Council (NHMRC) having set a goal for all Australians to have a blood lead level below 10 µg/dL, there is no requirement under any Australian legislation for DIY renovators to adhere to practices which would actually achieve this goal. There would be people dry sanding such apparently unpainted wooden surfaces everyday without protection. The reason we don't recognise that this is causing lead poisoning of renovators is that blood lead testing is incredibly rare in Australia.
I trust this answers your question.
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