The New Engineer
This is a final version submitted for publication. Minor editorial changes may have subsequently been made.
Engineers rely on standards in their design and specification work, often without realising that they do not provide full protection to themselves or others, because they are overly influenced by vested interests. A key aspect of standard setting is the composition of the technical committee that writes the standard. Standards Australia claims to seek participation of a wide range of organisations but often environmental and health interests are neglected and consumer and engineering interests are always a small minority.
An example is Australian Standard AS 1604: 1997 for preservative-treated timber. The main preservative used in Australia is CCA (copper chrome arsenic). CCA is a toxic chemical which is considered to be a carcinogen even at very low concentrations. In Florida, a county sheriff won $US60,000 compensation when two of his horses died after gnawing on CCA-treated timber. In 1984 a US EPA attempt to ban consumer use of CCA was undermined by industry pressure.
One problem with CCA-treated timber is that it can leach arsenic into the soil. Researchers at the Connecticut Agricultural Experiment Station found that decks of CCA-treated timber could leach high amounts of arsenic into the soil. In Connecticut the legal limit for arsenic in residential soils is 10 ppm but after 8 years the soil under decks contained an average of 138 ppm.
Another major problem with CCA preserved timber is that it causes problem when it is disposed. In particular, incineration can be very dangerous because it releases toxins into the air. But CCA preserved timber also poses a problem to those who handle it, particularly children. A 1990 US Consumer Product Safety Commission found that children playing on playground equipment made of CCA-treated timber got arsenic on their hands and ingested it when they put their hands in their mouths. It found a two year old could ingest hundreds of times what is considered in the US to be a safe daily dose in this way.
Yet AS 1604 ignores these health and environmental problems. No limits on leaching are given nor does the standard specify methods to be used for fixing CCA. No mention is made of disposal methods. This is not so surprising when one considers the composition of the committee. The organisations represented on the committee are the CSIRO, Division of Forest Products which is partially funded by at least one timber preservation company, the Housing Industry Association of Australia, the National Association of Forest Industries (NAFI), the NZ Timber Industry Federation, the NZ Timber Preservers Council, the Plywood Association of Australia, the Queensland Forest Service, RMIT, State Forests of NSW, the Timber Preservers Association of Australia and IEAust: no community representatives, environmentalists, public health organisations and a committee completely dominated by timber suppliers and timber treaters.
The IEAust member on the committee, Peter Campbell, has problems with the standard but tends to be outvoted when he tries to introduce changes. Campbell points out that specifying the AS 1604 standard in a contract may not relieve the design engineer from liability for timbers that do leach in service as it may be construed that s/he provided inadequate specification. He is also concerned that there have not been adequate field tests to provide a basis for specifying protection levels in various environments.
Another problem, that shows the influence of the timber producers on the standard, is that it requires designers and users to sample and test any structural timber to ensure it complies with the standard. This removes the burden of maintaining quality control from the producer and the burden of checking to the purchaser, a particularly onerous task given that in many cases penetration is unpredictable.
This situation of inadequate engineering representation and too much influence from vested interests is by no means unique to the preservative treated timber standards committee. Campbell argues that, given this situation, engineers who use and rely on standards outside of their own area of expertise need to have access to critical commentaries and that an IEAust web page for this purpose would be one way of doing this. There also needs to be some better way of addressing health and environmental concerns.