MCS - Multiple Chemical Sensitivities
MCS is a syndrome that has received alot of good research funding, but not very recently. There are a slew of good articles, and one researcher, Martin Pall, from Washington State University, that pulled most of it together about 15 years ago before we had more access to all of the current genetics.
In sum, through a variety of insults and dysregulated cytokines and inflammatory processes, the TRP and NMDA receptors become sensitized in the brain. This neural sensitization then becomes quite easily activated in the presence of very low levels of many different irritants. Some of the main players in this process include : IL2, IL-4. IL-6, IL-10, TNF Alpha, NFK Beta, INF Gamma. Ring a bell ? And not to leave out Super Oxide, Nitric Oxide (iNOS), EMF exposure.
Some of the commonly well known irritants include: Mold (ochratoxin A), Solvents (benzene, ethyl benzene, Toluene, Styrene, Xylene, etc), Glyphosate, organo phospates (glyphosate), electrophyllics, pesticides (organochlorines, carbamate, pyrothyroid), saran gas, hydrophyllics, carbon monoxide, mercury, and hydrogen sulfide. [1,2].
Additionally there are several well documented correlations to genetic mutations by several well established researchers:
PON1 - Organo Phosphates , Saran Gas; [4,6,7]
CYP2D6 - Organo Phosphates; [4,7]
NAT2- Mycotoxins; [4,6]
GSTT1 - Hydrophyllic, Electrophyllics 
GSTP1 - Hydrophyllic, Electrophyllics 
GSTM1 - Electrophyllics 
UGT1A1- Glucuronidation - Ochratoxin A; 
SOD2 - Oxidative Stress; 
CCK-D Stimulates NMDA Activity; 
Capsaicin - NMDA Sensitivity ; 
I will be adding more to this blog post in the future, but needless to say, there has been lots of research, and it points to a couple of clear things. One, there are genetic pre dispositions, and its well documented. Two, there is an exposure issue and neuro sensitization process. The healing process must account for both of these and more importantly the intertwined immune response to the above - which is complex - but required to enact a healing program. I will be adding some more details and information on the genetics involved in the inflammatory cascade (TNF Alpha, etc).
How to resolve MCS is not universal - it largely depends on the persons genetics so the intervention can be specific and most effective. Genetics and key bio markers like : IL-2, IL-4, IL-6, IL-8, IL-10, IL-13, TNFA, NFKBSCD40L, VEGF, etc. I will be putting a follow on section on what an approach may look like to begin to calm down the neuro activation an immune activation.
 Multiple Chemical Sensitivity, Gesualdo M. Zucco1,* and Richard L. Doty. Journal List Brain Science PMC8773480. Brain Sci. 2022 Jan; 12(1): 46. Published online 2021 Dec 29.
doi: 10.3390/brainsci12010046. PMCID: PMC8773480. PMID: 35053790
 Case-control study of genotypes in multiple chemical sensitivity: CYP2D6, NAT1, NAT2, PON1, PON2 and MTHFR. Gail McKeown-Eyssen, Cornelia Baines, David EC Cole, Nicole Riley, Rachel F Tyndale, Lynn Marshall, Vartouhi Jazmaji. International Journal of Epidemiology, Volume 33, Issue 5, October 2004, Pages 971–978, https://doi.org/10.1093/ije/dyh251. Published: 15 July 2004
 A single TRPV1 amino acid controls species sensitivity to capsaicin. Ying Chu, Bruce E. Cohen & Huai-hu Chuang. Scientific Reports. Published: 15 May 2020. Scientific Reports volume 10, Article number: 8038 (2020)
 Genetic susceptibility factors for multiple chemical sensitivity revisited. Nikolaj Drimer Berg, Henrik Berg Rasmussen , Allan Linneberg , et al. Environmental Health. Volume 213, Issue 2, March 2010, Pages 131-139. International Journal of Hygiene and Environmental Health. https://doi.org/10.1016/j.ijheh.2010.02.001
 A cross-sectional study of self-reported chemical-related sensitivity is associated with gene variants of drug-metabolizing enzymes. Eckart Schnakenberg, Karl-Rainer Fabig, et al . Journal List Environ Health v.6; 2007 PMC1802749. Environ Health. 2007; 6: 6. Published online 2007 Feb 10.
doi: 10.1186/1476-069X-6-6. PMCID: PMC1802749. PMID: 17291352
 Review of evidence for a toxicological mechanism of idiopathic environmental intolerance. LH Hetherington , JM Battershill. https://doi.org/10.1177/0960327112457189
 Elevated nitric oxide/peroxynitrite theory of multiple chemical sensitivity: central role of N-methyl-D-aspartate receptors in the sensitivity mechanism. Martin L Pall. Journal List Environ Health Perspect v.111(12); 2003 Sep PMC1241647. Environ Health Perspect. 2003 Sep; 111(12): 1461–1464.
doi: 10.1289/ehp.5935. PMCID: PMC1241647. PMID: 12948884
 Multiple Chemical Sensitivity: Toxicological and Sensitivity Mechanisms. Prof. Martin L. Pall
Professor Emeritus of Biochemistry and Basic Medical Sciences, Washington State University
and Research Director, The Tenth Paradigm Research Group. 638 NE 41st Ave. Portland, OR 97232-3312 USA. 503-232-3883. email@example.com
 Evaluation of Genetic Polymorphisms in Patients with Multiple Chemical Sensitivity. Xiaoyi Cui ,Xi Lu,Mizue Hiura,Masako Oda,Wataru Miyazaki,Takahiko Katoh. Published: August 13, 2013. https://doi.org/10.1371/journal.pone.0073708