Top 25 environmental exposures associated with autoimmunity
| Rank | Exposure | Autoimmune associations | Evidence |
|---|---|---|---|
|
1 |
Crystalline silica | SSc, RA, SLE, ANCA vasculitis | ★★★★★ |
|
2 |
Cigarette smoke | RA, SLE, MS, Graves disease | ★★★★★ |
|
3 |
Trichloroethylene (TCE) | Systemic sclerosis, SLE/autoimmune responses | ★★★★½ |
|
4 |
Organic solvents | SSc, SLE, MS, systemic autoimmune disease | ★★★★ |
|
5 |
Mercury/methylmercury | ANA/autoantibodies; autoimmune dysregulation | ★★★★ |
|
6 |
PM2.5/air pollution | RA, CTD, IBD, psoriasis, possibly SLE | ★★★★ |
|
7 |
Agricultural pesticides | RA, SLE, Sjögren syndrome | ★★★★ |
|
8 |
PFAS—especially PFOA/PFOS | Celiac/IBD; immune dysregulation; emerging thyroid/RA evidence | ★★★½ |
|
9 |
Tetrachloroethylene/PCE | Systemic sclerosis/autoimmune associations | ★★★½ |
|
10 |
PCBs | Thyroid autoimmunity/immune dysregulation; possible MS/RA links | ★★★ |
|
11 |
Dioxin/TCDD | Autoimmune immune modulation | ★★★ |
|
12 |
Organochlorine pesticides | RA/SLE/autoantibody associations | ★★★ |
|
13 |
Organophosphate pesticides | RA/systemic autoimmune associations | ★★★ |
|
14 |
Chlorpyrifos | Immunotoxicity; autoimmune evidence developing | ★★½ |
|
15 |
Cadmium | RA, autoantibodies, inflammatory immune dysregulation | ★★½ |
|
16 |
Arsenic | Autoimmune/inflammatory immune dysregulation | ★★½ |
|
17 |
Lead | Autoantibody/immune alterations; human autoimmune evidence limited | ★★½ |
|
18 |
Bisphenol A | Thyroid/lupus/RA mechanisms; human evidence emerging | ★★½ |
|
19 |
Phthalates/DEHP | Autoimmune/endocrine-immune dysregulation | ★★½ |
|
20 |
PBDE flame retardants | Thyroid autoimmunity/immune disruption | ★★ |
|
21 |
Benzene | Profound immunotoxicity; autoimmune associations less established | ★★ |
|
22 |
PAHs | RA/SLE inflammatory and autoimmune pathways | ★★ |
|
23 |
DDT/DDE | Autoimmune/endocrine immune effects | ★★ |
|
24 |
Formaldehyde | Immune activation/occupational inflammatory disease; systemic autoimmunity uncertain | ★½–★★ |
|
25 |
Styrene | Immune dysregulation; limited direct autoimmune epidemiology | ★½ |
1. CRYSTALLINE SILICA — strongest toxicant association
This belongs at or near the top because human occupational studies repeatedly associate silica exposure with:
systemic sclerosis, rheumatoid arthritis, systemic lupus erythematosus and ANCA-associated small-vessel vasculitis.
A huge Danish occupational cohort demonstrated a dose-dependent association between respirable crystalline silica and autoimmune rheumatic disease, especially systemic sclerosis and RA.
Mechanisms
Silica particles can produce:
- macrophage injury
- inflammasome activation
- oxidative stress
- chronic pulmonary inflammation
- release of intracellular autoantigens
- loss of immune tolerance
- ANA/autoantibody production
Full references
Boudigaard SH, Schlünssen V, Vestergaard JM, et al. Occupational exposure to respirable crystalline silica and risk of autoimmune rheumatic diseases: a nationwide cohort study. International Journal of Epidemiology. 2021;50(4):1213-1226.
Gómez-Puerta JA, Gedmintas L, Costenbader KH. The association between silica exposure and development of ANCA-associated vasculitis: systematic review and meta-analysis. Autoimmunity Reviews. 2013;12(12):1129-1135.
Parks CG, Conrad K, Cooper GS. Occupational exposure to crystalline silica and autoimmune disease. Environmental Health Perspectives. 1999;107 Suppl 5:793-802.
2. CIGARETTE SMOKE
Smoking is one of the best-established environmental risk factors for seropositive rheumatoid arthritis, particularly ACPA-positive RA.
The interaction between smoking and genetic susceptibility, especially certain HLA-DRB1 shared-epitope alleles, is particularly important.
Smoking promotes pulmonary protein citrullination, potentially facilitating ACPA formation.
It has also been associated with:
- systemic lupus erythematosus
- Graves disease
- multiple sclerosis
- poorer outcomes in several autoimmune diseases
A recent causal-risk analysis continues to identify smoking as an important modifiable RA risk factor.
Full reference
Morotti A, Sollaku I, Franceschini F, et al. Systematic review and meta-analysis on the association of occupational exposure to free crystalline silica and tobacco smoking with rheumatoid arthritis. Clinical Reviews in Allergy & Immunology. 2022.
3. TRICHLOROETHYLENE — TCE
TCE is one of the most interesting individual chemicals in environmental autoimmunity.
Associations have particularly concerned:
- systemic sclerosis
- lupus-like autoimmunity
- increased ANA
- autoimmune hepatitis-like processes
Experimental lupus-prone models provide unusually extensive mechanistic evidence.
Mechanisms
TCE or its metabolites may alter:
- CD4+ T-cell regulation
- oxidative stress
- protein modification
- cytokine balance
- IFN-γ pathways
- regulatory T-cell function
Full references
Cooper GS, Makris SL, Nietert PJ, Jinot J. Evidence of autoimmune-related effects of trichloroethylene exposure from studies in mice and humans. Environmental Health Perspectives. 2009;117(5):696-702. doi:10.1289/ehp.11782.
Cai P, Konig R, Boor PJ, et al. Chronic exposure to trichloroethene causes early onset of SLE-like disease in female MRL+/+ mice. Toxicology and Applied Pharmacology. 2008;228(1):68-75.
4. ORGANIC SOLVENTS
This includes occupational exposure to mixtures containing chemicals such as:
- TCE
- PCE
- aromatic hydrocarbons
- paint/degreasing solvents
A systematic review and meta-analysis found an association between solvent exposure and autoimmune diseases.
Particularly notable is systemic sclerosis. A systematic review concluded that silica and solvents were among the occupational exposures most consistently related to SSc.
Full references
Barragán-Martínez C, Speck-Hernández CA, Montoya-Ortiz G, et al. Organic solvents as risk factor for autoimmune diseases: a systematic review and meta-analysis. PLoS ONE. 2012;7(12):e51506. doi:10.1371/journal.pone.0051506.
Rubio-Rivas M, Moreno R, Corbella X. Occupational and environmental scleroderma: systematic review and meta-analysis. Clinical Rheumatology. 2017;36:569-582.
5. MERCURY / METHYLMERCURY
Mercury has one of the most developed experimental models of chemical-induced autoimmunity.
Human evidence is particularly interesting for autoantibody formation rather than proven clinical autoimmune disease.
In U.S. NHANES women, mercury exposure was associated with increased odds of high-titer ANA positivity.
Mechanisms
Mercury may promote:
- polyclonal B-cell activation
- ANA formation
- nucleolar autoantibodies
- altered T-cell signaling
- increased inflammatory cytokines
- breakdown of self-tolerance
Full references
Somers EC, Ganser MA, Warren JS, et al. Mercury exposure and antinuclear antibodies among females of reproductive age in the United States: NHANES. Environmental Health Perspectives. 2015;123(8):792-798. doi:10.1289/ehp.1408751.
Pollard KM, Cauvi DM, Toomey CB, Morris KV, Kono DH. Mercury-induced inflammation and autoimmunity. Biochimica et Biophysica Acta—General Subjects. 2019;1863(12):129299. doi:10.1016/j.bbagen.2019.02.001.
6. PM2.5 AND AIR POLLUTION
Increasing epidemiologic evidence associates chronic air-pollution exposure with:
- rheumatoid arthritis
- connective-tissue diseases
- inflammatory bowel disease
- psoriasis
- possibly systemic lupus
A large study found long-term pollution exposure associated with increased autoimmune-disease risk.
Full reference
Adami G, Pontalti M, Cattani G, et al. Association between long-term exposure to air pollution and immune-mediated diseases: a population-based cohort study. RMD Open. 2022;8:e002055.
7. AGRICULTURAL PESTICIDES
Pesticide exposure has been associated with rheumatoid arthritis, SLE and Sjögren syndrome, although risks differ greatly by individual pesticide.
The Agricultural Health Study provides some of the best human data.
Full references
Parks CG, Walitt BT, Pettinger M, et al. Insecticide use and risk of rheumatoid arthritis and systemic lupus erythematosus in the Women’s Health Initiative Observational Study. Arthritis Care & Research. 2011.
Parks CG, Meyer A, Beane Freeman LE, et al. Pesticide use and risk of systemic autoimmune diseases in the Agricultural Health Study. Environment International. 2022.
8. PFAS — PFOA/PFOS/PFHxS/PFNA
PFAS are unquestionably immunotoxic, but direct evidence for causing classic systemic autoimmunity is less developed than the evidence for silica or smoking.
Current evidence is strongest for:
- altered antibody responses
- immune-cell alterations
- celiac disease/IBD associations
- possible thyroid autoimmune effects
- emerging RA/MS associations
A new systematic/scoping evaluation found the strongest autoimmune-related evidence for gastrointestinal immune-mediated diseases, while RA and other associations remain less certain.
Full references
Holm-Larsen CE, et al. Exposure to per- and polyfluoroalkyl substances (PFAS) and development of autoimmunity: a systematic evidence review. 2026. PubMed PMID 42034718.
Rudzanova B, et al. Impact of PFAS exposure on prevalence of immune-mediated diseases in adults. Environmental Research. 2023.
9. TETRACHLOROETHYLENE — PCE
PCE is a chlorinated solvent historically associated particularly with:
- dry cleaning
- metal degreasing
- groundwater contamination
Solvent-exposure studies implicate chlorinated solvents in systemic sclerosis and other systemic autoimmune diseases, although evidence for PCE individually is weaker than TCE.
Full reference
Barragán-Martínez C, Speck-Hernández CA, Montoya-Ortiz G, et al. Organic solvents as risk factor for autoimmune diseases: a systematic review and meta-analysis. PLoS ONE. 2012;7:e51506. doi:10.1371/journal.pone.0051506.
10. POLYCHLORINATED BIPHENYLS — PCBs
PCBs are persistent, lipophilic pollutants with endocrine and immunological effects.
Potential associations include:
- thyroid autoimmunity
- altered immunoglobulin production
- altered T-cell/B-cell function
- emerging MS associations
The evidence for immune toxicity is stronger than the evidence for causation of specific autoimmune diseases.
Full reference
Khan MF, Wang H. Environmental exposures and autoimmune diseases: contribution of gut microbiome. Frontiers in Immunology. 2020;10:3094. doi:10.3389/fimmu.2019.03094.
11. DIOXIN / TCDD
TCDD acts primarily through the aryl hydrocarbon receptor (AhR) and can dramatically alter immune differentiation.
Potential effects include changes in:
- Treg cells
- Th17 cells
- dendritic cells
- B-cell responses
- cytokine signaling
Full reference
Huang RG, et al. Endocrine-disrupting chemicals and autoimmune diseases. 2023. PubMed PMID 37224951.
12. ORGANOCHLORINE PESTICIDES
Examples include:
- DDT
- DDE
- chlordane
- heptachlor
- lindane
They are persistent and can disrupt endocrine and immune signaling.
Associations with autoimmune diseases are intriguing but less consistent than silica/TCE.
Full reference
Parks CG, De Roos AJ. Pesticides, chemical and industrial exposures in relation to systemic lupus erythematosus. Lupus. 2014.
13. ORGANOPHOSPHATE PESTICIDES
Organophosphates are best known for acetylcholinesterase inhibition, but chronic exposure also influences:
- inflammatory cytokines
- oxidative stress
- T-cell activity
- immune regulation
Some agricultural studies associate pesticide use with RA and systemic autoimmune illness.
Full reference
Parks CG, Hoppin JA, De Roos AJ, et al. Rheumatoid arthritis in Agricultural Health Study spouses: associations with pesticides and other farm exposures. Environmental Health Perspectives. 2016.
14. CHLORPYRIFOS
Chlorpyrifos deserves separate consideration because of widespread historical use and substantial neuro/immunotoxicology.
However, the evidence for direct human autoimmune disease causation remains limited.
Full reference
Mostafalou S, Abdollahi M. Pesticides and human chronic diseases: evidences, mechanisms, and perspectives. Toxicology and Applied Pharmacology. 2013;268(2):157-177.
15. CADMIUM
Cadmium exposure comes from:
- tobacco
- diet
- industrial emissions
- batteries
- occupational exposure
It can alter macrophage and lymphocyte function and generates substantial oxidative stress.
Modern reviews identify cadmium among toxic metals potentially involved in autoimmune pathogenesis, although direct epidemiological evidence remains incomplete.
Full reference
Bjørklund G, Wallace DR, Kangarlou K, Hossain F, Peana M. Environmental toxins and toxic metals in autoimmune diseases: sex differences, hormonal influences, and immune dysregulation. Autoimmunity Reviews. 2026;25(1):103955. doi:10.1016/j.autrev.2025.103955.
16. ARSENIC
Chronic arsenic exposure produces profound changes in:
- oxidative stress
- epigenetic regulation
- inflammatory cytokines
- T-cell signaling
- innate immunity
Evidence linking arsenic to specific autoimmune diseases remains suggestive rather than definitive.
Full reference
Bjørklund G, Wallace DR, Kangarlou K, Hossain F, Peana M. Environmental toxins and toxic metals in autoimmune diseases: sex differences, hormonal influences, and immune dysregulation. Autoimmunity Reviews. 2026;25(1):103955. doi:10.1016/j.autrev.2025.103955.
17. LEAD
Lead clearly affects immune function, particularly at substantial or chronic exposure.
Reported mechanisms include:
- altered cytokine production
- oxidative stress
- T-cell dysregulation
- altered antibody production
But epidemiologic evidence for specific autoimmune disease caused by lead is considerably weaker than its neurodevelopmental, renal and cardiovascular toxicity.
Full reference
Bjørklund G, Wallace DR, Kangarlou K, Hossain F, Peana M. Environmental toxins and toxic metals in autoimmune diseases: sex differences, hormonal influences, and immune dysregulation. Autoimmunity Reviews. 2026;25(1):103955. doi:10.1016/j.autrev.2025.103955.
18. BISPHENOL A — BPA
BPA interacts with estrogen receptors and other endocrine pathways capable of influencing immunity.
Experimental evidence suggests effects on:
- B-cell activation
- antibody production
- Th17/Treg balance
- inflammatory cytokines
Human autoimmune evidence remains emerging.
Full reference
Huang RG, et al. Endocrine-disrupting chemicals and autoimmune diseases. 2023. PubMed PMID 37224951.
19. PHTHALATES / DEHP
Phthalates have widespread exposure through plastics and consumer products.
They can affect:
- endocrine signaling
- oxidative stress
- inflammatory cytokines
- immune-cell differentiation
Evidence linking them to specific autoimmune diseases remains less robust than for silica, smoking or TCE.
Full reference
Bjørklund G, Wallace DR, Kangarlou K, Hossain F, Peana M. Environmental toxins and toxic metals in autoimmune diseases: sex differences, hormonal influences, and immune dysregulation. Autoimmunity Reviews. 2026;25(1):103955. doi:10.1016/j.autrev.2025.103955.
20. PBDE FLAME RETARDANTS
PBDEs are persistent flame retardants formerly used heavily in:
- furniture foam
- electronics
- textiles
They can alter thyroid hormone and immune signaling. Research into autoimmune thyroid disease is biologically plausible but remains developing.
Full reference
Kosarek NN, et al. Contributions of synthetic chemicals to autoimmune disease development. 2024. PubMed PMID 38653907.
21. BENZENE
Benzene is a potent bone-marrow and immune-system toxicant.
It alters:
- hematopoietic stem cells
- lymphocyte populations
- oxidative pathways
- immune competence
However, benzene’s strongest established human effect is hematologic toxicity and leukemia, not classic autoimmune disease.
Full reference
Khan MF, Wang H. Environmental exposures and autoimmune diseases: contribution of gut microbiome. Frontiers in Immunology. 2020;10:3094. doi:10.3389/fimmu.2019.03094.
22. POLYCYCLIC AROMATIC HYDROCARBONS — PAHs
PAHs occur in:
- tobacco smoke
- diesel exhaust
- wildfire smoke
- traffic pollution
- charred foods
Possible autoimmune mechanisms include oxidative stress, AhR activation and epigenetic alteration.
Their contribution is difficult to separate from the overall effects of particulate air pollution and smoking.
Full reference
Celen H, et al. Airborne pollutants as potential triggers of systemic autoimmune rheumatic diseases: a narrative review. Clinical Rheumatology. 2022.
23. DDT / DDE
DDT and its persistent metabolite DDE can remain in humans for years.
Potential effects include:
- endocrine disruption
- altered cytokine signaling
- immune modulation
Evidence for specific autoimmune diseases remains limited/emerging.
Full reference
Parks CG, De Roos AJ. Pesticides, chemical and industrial exposures in relation to systemic lupus erythematosus. Lupus. 2014.
24. FORMALDEHYDE
Formaldehyde is clearly capable of producing:
- mucosal inflammation
- sensitization
- occupational respiratory disease
- immune activation
But evidence that ordinary formaldehyde exposure produces a systemic autoimmune disease such as lupus or RA remains weak.
Full reference
Cooper GS, Miller FW, Germolec DR. Occupational exposures and autoimmune diseases. International Immunopharmacology. 2002;2:303-313.
25. STYRENE
Styrene can influence oxidative and inflammatory pathways, but direct human evidence for systemic autoimmune disease is limited.
It belongs toward the bottom rather than the top of an evidence-ranked autoimmune list.
Full reference
Barragán-Martínez C, Speck-Hernández CA, Montoya-Ortiz G, et al. Organic solvents as risk factor for autoimmune diseases: a systematic review and meta-analysis. PLoS ONE. 2012;7(12):e51506. doi:10.1371/journal.pone.0051506.
The 10 I would take most seriously
For a physician evaluating environmentally associated autoimmunity, I would prioritize the history around:
crystalline silica → cigarette smoke → TCE → occupational organic solvents → mercury → chronic particulate air pollution → agricultural pesticides → PFAS → PCE/chlorinated solvents → persistent organochlorines/PCBs.
This ranking reflects quality of evidence, not merely theoretical biochemical effects. A modern review identifies solvents, crystalline silica, mercury, pesticides and cigarette smoking among the environmental exposures with particularly substantial evidence for autoimmune involvement.
An especially important example is silica: a cohort covering more than 3 million Danish workers found exposure-dependent increases in systemic autoimmune rheumatic diseases, with the clearest relationships for systemic sclerosis and rheumatoid arthritis.
Likewise, a meta-analysis found a significant association between organic solvent exposure and autoimmune disease, while TCE possesses both human epidemiologic evidence and unusually strong mechanistic animal evidence.
Two clinical cautions
A positive ANA is not proof of toxin-induced autoimmune disease. For example, the mercury-NHANES study is important because methylmercury exposure correlated with high-titer ANA, but that represents subclinical autoimmunity, not proof that mercury caused lupus or another diagnosed autoimmune disease in those subjects.
Likewise, immunotoxicity is not synonymous with autoimmunity. PFAS are a good illustration: evidence that PFAS can impair vaccine-antibody responses and alter immune function is strong, whereas evidence tying individual PFAS directly to specific autoimmune diseases is considerably less settled.