CHAPTER 6
The release concentration rates of a chemical vary depending on the environmental conditions and compartment to which chemicals are released as well as on the use patterns (intended/unintended) of the product, possible breakdown of the product and wearing as explained in Chapter 3.2.
Even if the release concentration of a chemical be low, the volume of products used may be large. The use volume is affected by the number of products as well as the frequency and duration of the use of the product.
When and where to expect releases – spatial and temporal distribution of releases
The technical service lives of products vary from several decades to short periods. Releases may occur first a long time after the products are taken into use, and be distributed evenly over the entire service life of the product or occur under a specific period during the use of the product.
Generally, releases from the use of a product are most likely to occur - during the first use of a product
- when carrying out maintenance of the product
- due to wearing, exposure to heat or light or other ageing of the product
A product may be transferred between different countries in the world during its life-cycle, even the different parts of a single product can be manufactured in different countries.
Products such as electronics, textiles, toys and jewellery, mercury thermometers and paints could be produced in China and India and marketed in Africa, Europe and United States. In addition, the disposal of products can take place in the country where it is used or the used products can be shipped to other countries where the product parts can be recycled and used in new items. Some chemicals remain in the product through the supply chain and end up in unexpected places. However, some product groups may present health or environmental problems due to inadequate waste handling and recycling practices, the lack of organized and controlled waste treatment and related legislation in developing countries.
This is the case, for instance for electronic products. Due to the lack of information on the chemical content of the product, people in different countries (including manufacturers, repair personnel, consumers and recycling workers) can be exposed to hazardous chemicals in products (Agarwal 2009, Osibanjo 2009, Calabria 2007, McCarthy 2007, ChemicalWatch 2009c, Peytermann 2007).
When looking at releases from the use phase of end-products, it is important to pay attention to the fact that although the national surveillance of chemicals in products would be well organized, follow-up of chemicals in imported products may be challenging.
Also, the use place of the product may vary from stable (e.g. buildings), to mobile (e.g.
packaging material) or be variable (e.g. use of consumer products).
Over time, releases can be transported away from their original release site. Certain chemicals from the use of products, for instance brominated flame retardants, can be long-range transported in the air for thousands of kilometers and chemicals in suspended particulate matter can end up in surface waters and soil far from their original site and be released to the environment from the particles only a longer period after being released from the product material matrix.
Chemicals that are present in the product intentionally
If the properties of certain chemicals are needed to give the product the desired properties, these products are designed to retain the presence of the chemicals during the service life.
For instance, the functioning of batteries depends on certain heavy metals in the material, and therefore it is not likely to have high releases of these metals during the use of batteries.
Another example on this type of products is refrigerant gases in low-temperature apparatus.
High releases from these types of products can be expected mainly during apparatus breakdowns and due to unmanaged waste handling.
Chemicals that are present in the product unintentionally
Substances with functions that are relevant only during the manufacturing phase of a product can be expected to result in higher emission rates if these substances remain present in the product after it has entered the market. During the manufacturing of products chemicals may be embedded in the product as unwanted remains, such as pesticide residues in textiles from the manufacturing phase of natural fibres, or solvent residues in fresh print products.
The volume and quality of residual chemicals in the product vary and reliable information for a certain batch of a product can be retrieved accurately only by laboratory measurements.
Chemicals intended to be released from the products
The proper functioning of a product may require either that the chemicals are released in the desired manner, such as ink from ball point pens or colour cartridges, heavy metals during a fireworks display or propellant gas when using a fog horn, as well as different scent giving agents from, for instance, erasers or toys.
6.2 Release mechanisms and affecting factors
Release mechanisms and release rates of chemicals from the use-phase of end-products are affected both by the properties of the chemical present in the product and the product itself. At molecular level, the release volume depends on the concentration and properties of the chemical, the properties of the matrix to which it is bound, as well as on the type of bond between the chemical and the matrix.
Generally, low potential releases can be expected for a low release tendency chemical in a metal alloy. Examples of products from which high releases are likely are small molecular chemicals in a porous polymer material or chemicals with high vapour pressure.
A simplified scheme of the main factors affecting generation of releases from products during their use phase is provided in Figure 2.
Figure 2. Simplified diagram on factors influencing releases of chemicals from the use of products
Factors that have an impact on the release tendency during the use of a product
1 Chemical and physical factors
Releases from the use of a product are impacted by chemical and physical factors related to both the product material and the substances in the product.
The structure of the product can be simple or it can be composed of a large number of materials, such as plastic, metal, glass, ceramics, textile or leather. Note, that the properties of the product matrix can change due to aging or wearing of the product.
Chemical and physical factors of the product that impact releases during the use of the