While chlorine and bromine are widely recognized, reported and restricted as halogens in many applications, it is noteworthy that fluorine, iodine, and astatine (other Group 17/VIIA halogens on the Periodic Table of the Elements) are not restricted in the accepted industry definitions of “halogen-free”. Dependent on the industry considering the “halogen-free” designator, chlorine and bromine are the only halogens restricted and then at levels below 900-1,000 parts per million.
In the case of fluorine used in plastics, many anti-drip agents employed in “halogen-free” plastic compounds including polytetrafluoroethylene (PTFE), better known as Teflon®, contain fluorine and the anti-drip agents have been reported to be used in the 0.1-1.4 wt% range. Some of these products can contain significant quantities of fluorine exceeding the level typically accepted under IEC 61249-2-21 as content limits established for other halogens (0.09% or 900 parts per million). In other cases, fluorinated salts may be formulated into plastic products at typical levels of 800 parts per million, especially plastic parts produced from polycarbonate, to impart flame retardant properties while the product is labeled “halogen-free.”
Additionally, it is noteworthy to consider that fluorinated polymeric resins incorporated or alloyed into a plastic compound also do not contribute to the “halogen-free” standing of a finished polymer because of the omission of fluorine from the list of considered halogens. Such fluorinated resins that could be incorporated or alloyed to impart improved electrical, flammability and processing properties include:
o polyvinylidene fluoride (PVDF),
o ethylenetrifluoroethylene (ETFE)
o copolymers of ethylene and chlorotrifluoroethylene (ECTFE)
o polytetrafluoroethylene (PTFE)
o fluorinated ethylene propylene (FEP)
The apparent omission of fluorine, a halogen used in polymeric additives and plastics that are subsequently compounded into other plastics regularly to impart flame resistance and other properties, is due primarily to test methodology and limitations in detecting fluorine. The test methods employed to detect bromine and chlorine do not have the capability to detect fluorine and as such fluorine is left undetected and unreported although it too is a halogen. Without significant address in test methodology, it is unlikely that total halogen content will be considered by regulators in the near future; however, environmentalists have become aware of fluorine toxicology and the potential human effects in recent developments related to groundwater contamination by fluorinated compounds and potential effects of thermal decomposition of PTFE.
Recent concerns over the potential toxicological effects of groundwater contamination by some fluorinated precursors and by-products including perfluorooctanoic acid (PFOA) in the United States as well as potential human toxicological effects caused through contact with products containing PTFE produced by DuPont, better known as Teflon®, could cause a review of this apparent dual status for halogen materials used throughout industry. According to the environmental investigative organization Environmental Working Group:
“… in the past five years, the multi-billion dollar “perfluorochemical” (PFC) industry, which underpins such world-famous brands as Teflon®, Stainmaster®, Scotchgard® and Gore-Tex®, has emerged as a regulatory priority for scientists and officials at the U.S. Environmental Protection Agency (EPA). The PFC family is characterized by chains of carbon atoms of varying lengths, to which fluorine atoms are strongly bonded, yielding essentially indestructible chemicals that until recently were thought to be biologically inert. No one thinks so now.”
Since 2000, the United States Environmental Protection Agency (US EPA) has undertaken a significant review of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). [US EPA PFOA Factsheet] In 2000, the US EPA peremptorily forced the elimination of PFOS, the chemical used for decades as the active ingredient in the popular Scotchgard® stain and water repellant from 3M. At about the same time, 3M ceased manufacture of the related perfluorochemical PFOA.
Throughout 2005, the United States Environmental Protection Agency has had PFOA under intense regulatory scrutiny due to reports of groundwater contamination. PFOA is most widely used in the manufacture of PTFE. One significant brand of PTFE under scrutiny is Dupont Teflon®. Due to findings from toxicity studies and by the presence of PFOA in the blood of more than 90 percent of the United States population, the United States Environmental Protection Agency continues its review of human toxicity studies and potential health effects.
In December 2005, Dupont reached a US$16.5 million settlement agreement with the U.S. Environmental Protection Agency in an enforcement action related to the chemical compound PFOA; this settlement follows a civil settlement of US$107 million in March 2005 on related matters concerning alleged PFOA contamination of local drinking water by Dupont in West Virginia, USA.
In 2006, the issue of PFOA and PFOS content in plastics and other materials will be considered by many states. In California (USA), a coalition consisting of the United Steelworkers (USW), Sierra Club, Environmental Law Foundation, Environment California, U.S. Public Interest Research Group (PIRG), Natural Resources Defense Council (NRDC) and Environmental Working Group (EWG) filed a petition to have PFOA listed as “a chemical that is known to the state to cause cancer” under California’s Safe Drinking Water and Toxic Enforcement Act of 1986, commonly referred to as Proposition 65. If adopted, the finding would require information labels on products based on specific toxicological findings under California Right to Know requirements. Additionally, a preliminary report on perfluorochemical contamination in Minnesota was considered by the Senate Environmental Committee in February 2006.
In April 2006, sixteen lawsuits filed in a US$5 billion class-action suit have been transferred to a Federal Court in Des Moines, Iowa, USA. Court papers allege Teflon® makers withheld information about chemicals used to make Teflon® chemicals that are allegedly released when the pans are heated. Dupont, the manufacturer of Teflon® says the material is safe.
With the settlements in recent cases, pending class actions in Iowa (USA) related to potential human poisoning from fluorinated stick-free cooking surfaces and the information that has now been developed and exchanged during peer review, environmental watchdog groups and regulatory officials alike are continuing their reviews and investigations into the widespread use of perfluorochemicals in many industries with no immediate indication of potential outcome. It should be noted that the use of perfluorochemicals as anti-drip agents and flame retardants or the use of fluorinated polymers like PVDF or FEP has not been affected by any of the investigations to this point. However, because the use of perfluorochemicals is allowed within the guidelines of “halogen-free” materials, the reformulation of polymeric materials to eliminate the use of these scrutinized materials provides for significant opportunity from a technological development standpoint in providing truly “non-halogen” materials for the marketplace.
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Source by John Moritz