Thiocyanate Exposure Linked to Greater Arthritis Risk, Heightened Inflammation Indicators

Faming Pan, MD

Credit: Loop

Findings from a recent study are providing novel insight into the association between urinary thiocyanate levels and arthritis risk in young and middle-aged adults, further highlighting its effect on levels of various inflammatory indicators.¹

Leveraging National Health and Nutrition Examination Survey (NHANES) 2005-2016 data, results showed exposure to thiocyanate, either alone or in combination with perchlorate and nitrate, was associated with arthritis vulnerability. Findings also suggested greater thiocyanate was linked to increases in several inflammatory indicators, including white blood cells, centrocytes, lymphocytes, and systemic immune-inflammatory index.¹

“The intricate pathogenesis of arthritis involves a blend of genetic predisposition and environmental triggers,” principal investigator Faming Pan, MD, of the department of epidemiology and biostatistics at Anhui Medical University in China, and colleagues wrote.¹ “Hence, unveiling the underlying factors associated with arthritis holds paramount significance for effective control and prevention strategies.”

According to the US Centers for Disease Control and Prevention, an estimated 53.2 million US adults have arthritis, a number expected to grow in coming years. Its pathogenesis involves a combination of genetic predisposition and environmental triggers, although the impact of specific environmental contaminants on disease development is not well understood.^2,3

To examine the association between perchlorate, nitrate, and thiocyanate exposure with arthritis, as well as the potential role of inflammation in this context, investigators used NHANES data spanning from 2005 - 2016, excluding individuals > 60 years of age and who were missing data on arthritis questionnaire information, inflammation indicators, and urinary levels of perchlorate, nitrate, and thiocyanate as well as covariates of interest.¹

In total, investigators enrolled 6597 participants 20 - 59 years of age and ascertained their arthritis status based on healthcare provider diagnosis. Among the cohort, 1045 (15.8%) individuals had arthritis, 327 of whom had osteoarthritis and 224 of whom had rheumatoid arthritis (RA). NHANES data on participants’ urine samples were obtained and examined for the presence of thiocyanate, perchlorate, and nitrate.¹

Investigators pointed out several notable distinctions in demographic characteristics between the arthritic and non-arthritic groups, including sex, age, race, marital status, education, BMI, PIR, serum cotinine, diabetes mellitus, hypertension, gout, urinary creatinine, and thiocyanate (P <.05).¹

Upon analysis, the greatest exposure quartile (Q4) value of thiocyanate demonstrated a significant elevation in arthritis risk compared to Q1 (Odds ratio [OR], 1.60; 95% CI, 1.26 to 2.04). Of note, these associations remained significant for both osteoarthritis (OR, 2.03; 95% CI, 1.36, 3.06) and RA (OR, 2.43; 95% CI, 1.52 to 3.97). However, no association was observed between perchlorate and nitrate exposure with arthritis risk.¹

Given the potential for nonlinear and nonadditive dose-response relationships linked to exposure to these chemical mixtures, investigators employed Bayesian kernel-machine regression modeling for subsequent analyses. Incorporating this model, results showed a significant positive association between a combination of perchlorate, nitrate, and thiocyanate with arthritis risk, with thiocyanate being the predominant predictor.¹

Further analysis revealed a positive association between thiocyanate exposure and indicators of inflammation, including white blood cells (β 0.21; 95% CI, 0.15-0.26), neutrophils (β 0.17; 95% CI, 0.13-0.21), lymphocytes (β 0.03; 95% CI, 0.01-0.05), and systemic immune-inflammatory index (β 13.19; 95% CI, 5.37-21.00).¹

Investigators were careful to point out several limitations to these findings, including their reliance on questionnaires and self-reports for the identification of arthritis and its subtypes, their inability to account for certain potential confounders due to limitations in the NHANES dataset, and restrictions of cross-sectional study design for inferring causality and temporality.¹

“In conclusion, our study establishes a significant and positive association between thiocyanate exposure and the risk of developing arthritis, alongside a similar positive correlation with inflammatory markers in young and middle-aged adults,” investigators concluded.¹

References:

1. Zhao H, Chen X, Ni J, et al. Associations of perchlorate, nitrate, and thiocyanate exposure with arthritis and inflammation indicators in young and middle-aged adults, NHANES 2005-2016. Front Immunol. 2024;15:1318737. doi:10.3389/fimmu.2024.1318737
2. US Centers for Disease Control and Prevention. Fast Facts About Arthritis. Arthritis. October 4, 2023. Accessed March 22, 2024. https://www.cdc.gov/arthritis/basics/arthritis-fast-facts.html
3. Cleveland Clinic. Arthritis. Diseases & Conditions. November 13, 2023. Accessed March 22, 2024. https://my.clevelandclinic.org/health/diseases/12061-arthritis