Understanding Toxicity of Products – Part Three

Thursday, February 19th, 2015
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This is the third part of a three-part series explaining the technicalities of product toxicity labelling that will explain how to interpret product Safety Data Sheets (SDSs) and product warning labels.

This instalment considers the classification of chemicals and conventions to limit the use of some of the most persistent toxic substances.

Chemicals in the ‘Persistent Organic Pollutants’ (POPs) category are banned internationally under the Stockholm Convention, with highly hazardous pesticides and industrial chemicals being banned under Annexure III of the Rotterdam Convention.

However, there are other countless other substances of lesser but nonetheless toxic impacts that have been classified to assist in determining safe levels of exposure for humans and for ecosystems. If we decided to take the route of banning all toxic chemicals at all life stages of products’ manufacture, the majority of the materials and products we take for granted today would disappear, including most plastics and everyday chemicals used in the home and on site.

Managing the hazard risks to ensure personal and environmental safety therefore becomes a major task. As dealt with a recent article Product Transparency-Risk and Hazard, Hazard equals Risk times Exposure, but drilling down one step further, the degree of risk involves consideration of both the dose delivered and the toxicity of the chemical in the exposure. To simplify toxicity, the UN’s Globally Harmonized System of Classification and Labelling of Chemicals (GHS) has also created a series of toxicity codes and symbols (see part two of this series). Different organisations and countries have also developed categories denoting degrees of toxicity and effects.

The major ones likely to be relevant to most home owners and building professionals are defined as follows:

Toxicity: To indicate how these are determined, the EU defines chemicals as toxic when they are classified as carcinogenic (category 1A or 1B), mutagenic (category 1A or 1B), or toxic for reproduction (category 1A, 1B, or 2). Some toxins can also be classified as persistent, very persistent, bioaccumulative and very bioaccumulative (as denoted by R-Phrases and H-Statements).

Carcinogens: Substances capable of causing cancer. Chemicals classified by the ‘International Agency on Research into Cancer’ (IARC) are:

  • Category 1: Carcinogenic to humans
  • Category 2A: Probably carcinogenic to humans
  • Category 2B: Possibly carcinogenic to humans
  • Category 3A: Not classifiable as to carcinogenicity to humans-tested
  • Category 3B:  Not classifiable as to carcinogenicity to humans-untested
  • Category 4: Probably not carcinogenic to humans[1]

Mutagens:  Substances capable of impairing or modifying genes.

  • Category 1: Known to be mutagenic to humans
  • Category 2: Should be regarded as if they are mutagenic to humans
  • Category 3: Cause possible mutagenic concern for humans

Teratogens: Substances toxic to reproduction (developmental toxicity or impairment of fertility).

  • Category 1: Known to be toxic to reproduction in humans
  • Category 2: Should be regarded as if they are toxic to reproduction in humans
  • Category 3A: Cause possible developmental toxicity for humans
  • Category 3B: Cause possible impairment of fertility for humans

Endocrine disruptors: A variety of chemicals in common use today disrupt human and animal hormones. Some do this by mimicking the hormone oestrogen. They can cause developmental defects such as sperm loss, breast tissue growth in males and even sex conversion. Recently they have also been linked to breast cancer. Such chemicals typically are used as plasticisers (e.g. DOP/DEHP, DBD), other phthalates in vinyls (now banned in children’s toys) and other chemicals found in polycarbonates and epoxies ((such as BPA).

Each of the following categories also has category 1 and 2 subcategories with a similar structure to those above:

  • Respiratory Sensitisers: Substances that cause allergic or asthmatic symptoms or breathing difficulties if inhaled.
  • Contact Skin Sensitisers: Substances that cause allergic skin reactions.
  • Skin Corrosion: Substances that cause corrosion of the skin.
  • Skin Irritant:  Substances that cause corrosion irritations of the skin.
  • Eye Corrosiveness: Substances that cause effects from corrosion to irritation of the eyes.

Substances with the classifications listed above are obviously all still relevant in ecosystem health. However, in water-based ecosystems, other criteria such as eutrophication (oxygen depletion due to overgrowth of algae due to nutrient deposition) and acidification of soil, water and air (typically due to fossil fuel energy use, synthetic fertiliser and carbonation of water from greenhouse gases) use  also become relevant.

In a workplace context, to determine whether a substance or mixture is hazardous, using the HSIS lists, follow this approach:

Step 1: Identify each ingredient using the substance name, CAS Number or UN number

Step 2: Determine if the concentration of any ingredient is above the minimum concentration cut-off level (if so, the mixture is determined to be hazardous).

If any ingredient in the mixture does not appear on the HSIS, or is listed without at least one concentration cut-off level, then check other databases such as the EU ECHA, OECD eChemPortal or USA ToxNet.

If a mixture contains more than one ingredient that is in the HSIS consolidated listing, and all ingredient concentrations are below their respective minimum concentration cut-off levels, the mixture may still be considered hazardous if one or more of these ingredients exhibit corrosive, irritant or acute lethal effects.

In a product context, not only must workplace safety be considered, but the impacts across all life cycle stages. So safety cutoff levels for each potential pollution event/context and consideration of the risk of those events occurring need to be considered.

[1] http://www.iarc.fr/IARCPress/index.php
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