This is the first part of a three-part series explaining the technicalities of toxicity.
The issue was touched on in last months article, Product Transparency-Risk and Hazard, which talked about the need to use risk-based approaches to toxicity assessment rather than simply hazard-based assessment.
This series will introduce the details of how to approach and understand toxicity and risk assessment for green building professionals.
The most accessible (but only semi-reliable) resource for determining the health impact of any given products is its Safety Data Sheet (SDS), previously known as MSDS. These sheets are required to be produced by manufacturers to explain in a standardised format:
- The types of chemicals that comprise the product (with only broad indication of concentration)
- The effects of the finished product on humans and ecosystems
- Safety precautions to take in the event of any accident
- The manufacturer’s contact details
While they are required by legislation, the quality of the data provided by an SDS is extremely variable. Many manufacturers interpret the requirements for an SDS to relate to the impacts of the finished compound or product itself and don’t declare the impacts of the individual ingredients. If they believe there are no impacts of individual ingredients (such as when they have been reacted together to form another compound such as a polymer), they are not even mentioned.
It is important to remember that while the impact of a finished product is not necessarily the sum of its parts, the individual components that comprise a product can still actually have important health and environmental impacts in their own right.
Likewise, SDSs do not typically indicate whether a product will generate volatile organic compounds (VOCs), whether it contains unreacted components, undeclared contaminants or health issues generated by novel ultra low level toxicity thresholds that have been discovered in recent times.
This is particularly important when we look at highly toxic components (e.g. monomers that are combined to form essentially non-toxic compounds such as polystyrene, epoxy, PVC, synthetic rubber, polyurethane, ABS plastic, and so on) where the potential exists for unreacted or ‘free’ monomers that are carcinogenic to exist after the polymerisation reaction.
Residual free monomer or reactant levels in polymers are an emerging issue in some plastics, as it has been found that some of these chemicals can have significant impacts at much lower levels than previously thought and where novel ultra low emission thresholds are being established (for instance, Bisphenol A (BPA) in epoxies and polycarbonates; vinyl chloride monomer (VCM) in PVCs; isocyanate-based TDI or MDI monomers in polyurethanes; and styrene monomers in polystyrene, ABS, styrene butadiene rubber (SBR) or synthetic rubber.)
Because of this, SDSs should not be seen as a failsafe source of information on the potential risk of any given product, but as a compliance mechanism that relates mostly to transport safety and manufacturing facility OH&S issues. Care should be taken to ask for third party certification or test results of finished products from manufacturers for residual unreacted monomers when using these products, especially in situations where skin contact is common.
The most reliable source of information for assessment if you can obtain it is a full declaration of ingredients directly from the manufacturer. This is what third party ecolabels like Global GreenTag are able to achieve on your behalf.
To assess products yourself, systems such as the US-based Health Product Declaration or Declare systems provide valuable information. Once you know the ingredients, it is then possible to identify the Chemical Abstract Service identifier or CAS number and research it impacts via the online databases of bodies in Australia and also the European Union (EU), the US and the United Nations’ Globally Harmonized System of Classification and Labelling of Chemicals (GHS), as well as EU Directives 67/548/EEC and 2001/59/E and the EU REACH program.
These collectively represent the EU Regulation on the ‘Classification, Labelling and Packaging of Dangerous Substances and Mixtures’ and the related EU ESIS or European chemical Substances Information System. The system Australia has adopted is called HSIS or Hazardous Substances Information System..
HSIS is an internet resource that allows you to find information on substances that have been classified in accordance with the ‘Approved Criteria for Classifying Hazardous Substances.’ It is currently based on the EU Directive 67/548/EEC and is moving toward the adoption of REACH in the future. Currently, it appears to be about two years behind the EU REACH and GHS systems In addition to providing powerful search features, HSIS also provides direct access to a consolidated list of all the classified substances contained in the HSIS database.
The HSIS database provides searchable access to two data sets, one for hazardous substance information and the other for exposure standards information for human health impacts. While HSIS contains environmental toxicity data, this is not necessarily complete because its focus is on OH&S, so for accuracy ESIS or the GHS systems must also be checked. The HSIS can be searched by use of CAS numbers, UN identifier numbers or alphabetically.
Watch next month for part two of the series: Unravelling the Mysteries of Toxics Labelling.