The other day, someone responded to me asking why there is so much thyroid disorder and whether it is increasing or only being diagnosed more often. The part that has always confused me is what is causing the autoimmunity. I feel qualified to be an armchair speculator about some other aspects of thyroid disorders - but why do so many come down with autoimmune forms?
A recent paper suggest that Trichloroethylene has a role in autoimmunity (and hypersensitivity). This is an organic solvent which was widely used in many roles throughout much of the last century.
Considering this substance was used for dry cleaning, vegetable oil extraction, decaffeination of coffee, general anaesthetic (especially during birth), it is very likely that we have all had some exposure - and the older ones of us, quite a bit of exposure.
However, it is in much lower use these days so human exposure, at least in the UK, has probably reduced considerably.
I believe that decaffeination of coffee no longer uses organic solvents - so don't avoid decaffeinated coffee on those grounds. (Ha!)
Trichloroethylene has all sorts of other nasty effects such as causing cancers to Parkinson's disease - I was here trying to focus exclusively on the autoimmunity aspect.
Environ Health Perspect. 2012 Dec 18. [Epub ahead of print]
Human Health Effects of Trichloroethylene: Key Findings and Scientific Issues.
Chiu WA, Jinot J, Scott CS, Makris SL, Cooper GS, Dzubow RC, Bale AS, Evans MV, Guyton KZ, Keshava N, Lipscomb JC, Barone S Jr, Fox JF, Gwinn MR, Schaum J, Caldwell JC.
National Center for Environmental Assessment, U.S. Environmental Protection Agency, Washington, D.C., USA.
In support of the Integrated Risk Information System (IRIS), the Environmental Protection Agency (EPA) completed a Toxicological Review of Trichloroethylene (TCE) in September, 2011, the result of an effort spanning over twenty years.
This article reviews key findings and scientific issues regarding the human health effects of TCE in EPA's Toxicological Review.
This assessment synthesized and characterized thousands of epidemiologic, experimental animal, and mechanistic studies, and addressed several key scientific issues through modeling of TCE toxicokinetics, meta-analyses of epidemiologic studies, and analyses of mechanistic data.
Toxicokinetic modeling aided in characterizing the toxicological role of the complex metabolism and multiple metabolites of TCE. Meta-analyses of the epidemiologic data informed the conclusion that TCE causes kidney cancer in humans and provided strong evidence that TCE may also cause liver cancer and non-Hodgkin lymphoma. Mechanistic analyses support a key role for mutagenicity in TCE-induced kidney carcinogenicity. Recent evidence from both human and experimental animal studies indicates the involvement of TCE exposure in autoimmune disease and hypersensitivity. Recent avian and in vitro mechanistic studies provide biological plausibility that TCE plays a role in developmental cardiac toxicity, the subject of substantial debate due to mixed results from epidemiologic and rodent studies.
TCE is carcinogenic to humans by all routes of exposure and poses a potential human health hazard for non-cancer toxicity to the central nervous system, kidney, liver, immune system, male reproductive system, and the developing embryo/fetus.
Wiki article on the substance:
[Added 06/01/2013 10:25: If you have got this far, you may be interested that being exposed to mercury at the same time has even greater effects.
Toxicol Sci. 2011 Feb;119(2):281-92. doi: 10.1093/toxsci/kfq345. Epub 2010 Nov 17.
Coexposure to mercury increases immunotoxicity of trichloroethylene.
Gilbert KM, Rowley B, Gomez-Acevedo H, Blossom SJ.
Wonder if this co-exposure issue is why the dental establishment continually finds little or no impact when others disagree with that?]