Editing Halocarbon (section)

== Hazards ==

The stability of halocarbons tended to encourage beliefs that they were mostly harmless, although in the mid-1920s physicians reported workers in [[polychlorinated naphthalene|polychlorinated naphthalene (PCN)]] manufacturing suffering from [[chloracne]] {{Harv|Teleky|1927}}, and by the late 1930s it was known that workers exposed to PCNs could die from [[liver disease]] {{Harv|Flinn|Jarvik|1936}} and that [[DDT]] would kill [[mosquito]]s and other [[insect]]s {{Harv|Müller|1948}}. By the 1950s, there had been several reports and investigations of workplace hazards. In 1956, for example, after testing [[hydraulic]] oils containing [[polychlorinated biphenyl|polychlorinated biphenyl (PCB)]]s, the U.S. Navy found that skin contact caused fatal [[liver disease]] in animals and rejected them as "too toxic for use in a [[submarine]]" {{Harv|Owens v. Monsanto|2001}}.

[[File:Halogenated gas concentrations 1978-present.png|thumb|left|upright=1.2|Atmospheric concentration of several halocarbons, years 1978–2015.]]
In 1962 a book by U.S. biologist [[Rachel Carson]] {{Harv|Carson|1962}} started a storm of concerns about environmental [[pollution]], first focused on [[DDT]] and other [[pesticide]]s, some of them also halocarbons. These concerns were amplified when in 1966 Danish chemist Soren Jensen reported widespread residues of PCBs among Arctic and sub-Arctic fish and birds {{Harv|Jensen|1966}}. In 1974, Mexican chemist [[Mario Molina]] and U.S. chemist [[Sherwood Rowland]] predicted that common halocarbon [[refrigerant]]s, the [[chlorofluorocarbon]]s (CFCs), would accumulate in the upper [[atmosphere]] and destroy protective [[ozone]] {{Harv|Molina|Rowland|1974}}. Within a few years, [[ozone]] depletion was being observed above [[Antarctica]], leading to bans on production and use of [[chlorofluorocarbon]]s in many countries. In 2007, the [[IPCC Fourth Assessment Report|Intergovernmental Panel on Climate Change (IPCC)]] said halocarbons were a direct cause of [[global warming]].<ref>[http://www.ipcc.ch/SPM2feb07.pdf Climate Change 2007: The Physical Science Basis. Summary for Policymakers] {{Webarchive|url=https://web.archive.org/web/20070203164304/http://www.ipcc.ch/SPM2feb07.pdf |date=2007-02-03 }}, page 3</ref>

Since the 1970s there have been longstanding, unresolved controversies over potential health hazards of [[trichloroethylene]] (TCE) and other halocarbon [[solvent]]s that had been widely used for industrial cleaning {{Harv|Anderson v. Grace|1986}} {{Harv|Scott|Cogliano|2000}} {{Harv|U.S. National Academies of Science|2004}} {{Harv|United States|2004}}. More recently [[perfluorooctanoic acid]] (PFOA), a precursor in the most common manufacturing process for Teflon and also used to make coatings for fabrics and [[food packaging]], became a health and environmental concern starting in 2006 {{Harv|United States|2010}}, suggesting that halocarbons, though thought to be among the most inert, may also present hazards.

Halocarbons, including those that might not be hazards in themselves, can present [[waste disposal]] issues. Because they do not readily degrade in natural environments, halocarbons tend to accumulate. [[Incineration]] and accidental fires can create [[corrosive]] byproducts such as [[hydrochloric acid]] and [[hydrofluoric acid]], and [[poison]]s like halogenated [[Polychlorinated dibenzodioxins|dioxins]] and [[furan]]s. Species of Desulfitobacterium are being investigated for their potential in the [[bioremediation]] of halogenic organic compounds.<ref>{{Cite journal | last1 = Villemur | first1 = R. | last2 = Lanthier | first2 = M. | last3 = Beaudet | first3 = R. ©J. | last4 = Lépine | first4 = F. §O. | title = TheDesulfitobacteriumgenus | doi = 10.1111/j.1574-6976.2006.00029.x | journal = FEMS Microbiology Reviews | volume = 30 | issue = 5 | pages = 706–733 | year = 2006 | pmid =  16911041| doi-access = free }}</ref>