Here is a basic overview of one set of known problem chemicals: organic bromine and chlorine. Better known as substances in PVC pipe, electronics and other common product materials.
This overview of organic bromine and chlorine is quoted from a report by the International Chemical Secrtariat (www.chemsec.org) and Clean Production Action (www.cleanproduction.org)
Organic bromine and chlorine
Compounds that contain organic bromine and chlorine tend to be particularly likely to bioaccumulate, be persistent and/or toxic - or to degrade in the environment into new brominated or chlorinated organic compounds with these characteristics.
As they accumulate over time, these organo-halogen compounds can become widespread pollutants in air, water, soil, and sediment, where they are increasingly ingested by humans and animals. It is also important to note that inorganic forms of these chemicals can lead to the formation of dioxin and other problematic chemicals, particularly when they are mixed with organic matter.
Chlorinated dioxins and furans can cause severe health problems, including:
- Cancer
- Endocrine disruption
- Endometriosis
- Neurological damage
- Birth defects and impaired child development
- Reproductive system damage
- Immune system damage
Because dioxins and furans break down slowly, they endure in the environment for long periods of time.18,19 Like many organohalogens, they bioaccumulate in animals' fatty tissue. The highest concentrations are found in animals at the top of the food chain, including humans. Linda Birnbaum, a leading science expert on BFR s and dioxins, led the US EPA's 1994 dioxin assessment process, which concluded that for certain dioxins there was no safe level of exposure for humans.
Most of what we know about dioxins and furans is the result of the study of one particular dioxin: tetrachlorodibenzo-p-dioxin (TCD ), which is a developmental toxicant that causes skeletal deformities, kidney defects, and weakened immune responses in the offspring of animals exposed to it during pregnancy. The compound is also associated with some cancers and other health effects, including immune system alterations and skin lesions. Additionally, studies indicate many of the hundreds of other dioxins and furans are likely to cause similar health effects.
Dioxin precursors
Of particular concern is the ability of halogenated organics to act as precursors for generating dioxin, a potent known human carcinogen4 that is toxic at very low levels. Exposing halogenated organics such as the BFR s, CFR s, and PVC in electronics to incineration at insufficiently high temperatures or the uncontrolled burning practices commonly used in informal recycling in the developing world can generate dioxins, as well as furans, which can be equally toxic.
Chlorine Use in PVC
The predominant use of chlorine in electronics has been in PVC plastics. Most internal and external cables use PVC to insulate copper wires. Human health and environmental concerns about exposure to plastic additives used in PVC, such as lead, cadmium, and phthalates, as well as dioxin formation during the combustion of PVC components, triggered industry-wide efforts to replace PVC use in wire and cables. The major challenge has been developing alternative resins, that meet safety standards that in some instances were only written to specify PVC resins. To further complicate the situation, these safety standards vary geographically, forcing companies to use and get approval for multiple alternatives that comply with the different regional standards.
Bromine- and chlorine- based compounds are used extensively in the production of today's modern electronic products as flame retardants, solvents, dyes, adhesives and plastic resins.
The highest concentrations of bromine and chlorine are used in brominated and chlorinated flame retardants (BFR s and CFR s) and polyvinyl chloride (PVC).
However, in response to growing awareness of the human health and environmental problems associated with the use of bromine and chorine, leading manufacturers have started to restrict the use of these chemicals. These manufacturers have also come to recognize that the wide variety of halogenated compounds used in the electronics supply chain makes it very difficult to certify that specific brominated or chlorinated compounds have successfully been removed from electronics products.
Accordingly, some manufacturers have chosen to restrict the use of all substances containing these two elements, rather than contend with the difficulties involved in implementing and validating restrictions on specific, individual brominated and chlorinated substances. The method of focusing on chemicals on the group level rather than on individual compounds has come to be known as the elemental approach.
The Association Connecting Electronics Industries (IPC) is currently in the process of developing another standard for all plastic resins. The current proposal (September 2009) applies the elemental standard to a subset of brominated and chlorinated compounds, namely BFR s, CFR s, PVC, and PVC congeners in plastic resins. This approach, however, is more difficult to verify through testing and some companies are calling for a more verifiable approach that would apply restrictions on all uses of bromine and chlorine.