While chlorine and bromine are widely recognized, reported, and restricted as halogens in many applications, it should be noted that fluorine, iodine, and astatine (other Group 17/VIIA halogens in the Periodic Table of the Elements) are not restricted. in accepted industry definitions. of “halogen free”. Depending on which industry considers the “halogen free” designation, chlorine and bromine are the only halogens restricted and then at levels below 900-1000 parts per million.
In the case of fluorine used in plastics, many anti-drip agents used in “halogen-free” plastic compounds, including polytetrafluoroethylene (PTFE), better known as Teflon®, contain fluorine and anti-drip agents have been reported for use in the range of 0.1-1.4% by weight. Some of these products may contain significant amounts of fluorine that exceed the level normally accepted according to IEC 61249-2-21 as content limits established for other halogens (0.09% or 900 parts per million). In other cases, fluorinated salts can be formed in 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.”
In addition, it should be noted that fluorinated polymer resins incorporated or alloyed into a plastic compound also do not contribute to the “halogen-free” status of a finished polymer due to the omission of fluorine from the list of halogens considered. Such fluorinated resins that could be incorporated or alloyed to impart improved electrical, flammability, and processing properties include:
or polyvinylidene fluoride (PVDF),
or ethylenetrifluoroethylene (ETFE)
or copolymers of ethylene and chlorotrifluoroethylene (ECTFE)
or polytetrafluoroethylene (PTFE)
or fluorinated ethylene propylene (FEP)
The apparent omission of fluorine, a halogen used in polymer and plastic additives that are subsequently regularly mixed into other plastics to impart flame resistance and other properties, is primarily due to test methodology and limitations in fluoride detection. The test methods used to detect bromine and chlorine do not have the ability to detect fluorine and as such fluorine is not detected or reported, although it is also a halogen. Without significant direction on test methodology, regulators are unlikely to consider full halogen in the near future; however, environmentalists have become aware of the toxicology of fluorine and possible human effects in recent developments related to groundwater contamination by fluorinated compounds and the possible effects of thermal decomposition of PTFE.
Recent concerns about the potential toxicological effects of groundwater contamination by some fluorinated precursors and byproducts, including perfluorooctanoic acid (PFOA) in the United States, as well as potential human toxicological effects caused by contact with products containing contain PTFE produced by DuPont, better known as Teflon ® , could prompt a review of this apparent dual status of halogen materials used in industry. According to the environmental research organization Environmental Working Group:
“…in the last five years, the multi-billion dollar “perfluorochemicals” (PFC) industry, which underpins world famous brands such as Teflon®, Stainmaster®, Scotchgard® and Gore-Tex®, has become a priority regulator for US Environmental Protection Agency (EPA) scientists and officials. The PFC family is characterized by chains of carbon atoms of varying lengths, to which fluorine atoms are tightly bound, producing chemicals essentially indestructible that until recently were thought to be biologically inert. Nobody thinks that now.”
Since 2000, the United States Environmental Protection Agency (US EPA) has conducted a major review of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). [US EPA PFOA Factsheet] In 2000, the US EPA forcefully removed PFOS, the chemical used for decades as an active ingredient in 3M’s popular Scotchgard® water and stain repellent. Around the same time, 3M stopped manufacturing the related perfluorochemical PFOA.
Throughout 2005, the United States Environmental Protection Agency has subjected PFOA to intense regulatory scrutiny due to reports of groundwater contamination. PFOA is the most widely used in the manufacture of PTFE. One major brand of PTFE under scrutiny is Dupont Teflon®. Due to the findings of toxicity studies and 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 possible health effects.
In December 2005, Dupont reached a US$16.5 million settlement agreement with the US Environmental Protection Agency in an enforcement action related to the chemical compound PFOA; this settlement follows a $107 million civil settlement in March 2005 over matters related to the alleged PFOA contamination of local drinking water by Dupont in West Virginia, USA.
In 2006, many states will consider the issue of PFOA and PFOS content in plastics and other materials. In California (USA), a coalition made up of the United Steelworkers (USW), the Sierra Club, the Environmental Law Foundation, Environment California, the US Public Interest Research Group (PIRG), the Natural Resources Defense Council (NRDC) and the Environmental Working Group ( EWG) filed a petition to have PFOA listed as “a chemical known to the state to cause cancer” under California’s Safe Drinking Water and Toxic Enforcement Act of 1986, commonly known as Proposition 65. If If adopted, the finding would require information labels on products based on specific toxicology findings under California right-to-know requirements. Additionally, the Senate Environmental Committee considered a preliminary report on perfluorochemical contamination in Minnesota in February 2006.
In April 2006, sixteen lawsuits filed in a US$5 billion class action lawsuit transferred to Federal Court in Des Moines, Iowa, USA. Court documents allege that manufacturers of Teflon® withheld information about the chemicals used to make the Teflon® chemicals that are supposedly released when pans are heated. Dupont, the maker of Teflon®, says the material is safe.
With settlements in recent cases, pending class action lawsuits in Iowa, USA related to possible human poisoning from fluorinated nonstick cooktops, and information that has now been developed and shared during peer review, the Environmental watchdog groups and regulatory officials continue their reviews and investigations into the widespread use of perfluorochemicals in many industries with no immediate indication of the potential outcome. It should be noted that the use of perfluorochemicals as anti-drip agents and flame retardants or the use of fluorinated polymers such as PVDF or FEP have not been affected by any of the investigations carried out to date. However, because the use of perfluorochemicals is permitted within the “halogen-free” material guidelines, reformulation of polymeric materials to eliminate the use of these examined materials provides a significant opportunity from a technology development standpoint for provide truly “halogen-free” materials. materials for the market.
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