Breathing the Dusty Air at Your Workplace can Heighten the Risk of Rheumatoid Arthritis

A recent research indicates that, workplace exposure to gases, dust, fumes, and aromatic solvents used in paints, varnishes, and glues is linked to the development of rheumatoid arthritis. Furthermore, they appear to amplify the negative effects of smoking and genetic susceptibility to the disease, according to the findings.

There is increasing interest in attempting to understand what the risk factors are that lead to the development of rheumatoid arthritis (RA). Twin studies have proven a genetic role but also quantified the non-genetic risk. As a result, there is potential for identifying environmental predictors that could lead to a disease prevention strategy (1^✔ ✔Trusted Source
Risk factors for the development of rheumatoid arthritis

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Rheumatoid arthritis (RA) is a chronic inflammatory disease caused by both genetic and environmental factors. One of the most important extrinsic risk factors for its development and severity has been identified as smoking. Recent research has shed light on the pathophysiology of RA in smokers, including oxidative stress, inflammation, autoantibody formation, and epigenetic changes. Epidemiologic studies, as well as in vivo and animal models of RA, have shown a link between smoking and the development of RA (2^✔ ✔Trusted Source
Smoking and rheumatoid arthritis

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Silica exposure is also associated with an increased risk of developing rheumatoid arthritis. This association is not explained by smoking habits (3^✔ ✔Trusted Source
Silica exposure is associated with increased risk of developing rheumatoid arthritis: results from the Swedish EIRA study

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The joint effects of silica exposure and smoking were compatible with synergy between these two exposures in the development of rheumatoid arthritis, but this was not conclusive.

While cigarette smoking is known to increase the risk of developing rheumatoid arthritis, it is unknown what effect breathing in workplace dust and fumes may have.

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The researchers used data from the Swedish Epidemiological Investigation of RA to find out. This includes 4033 people who were newly diagnosed between 1996 and 2017 and 6485 others who were matched for age and gender but were disease-free (the comparison group).

Personal job histories were provided, and a validated technique was used to estimate the amount of individual exposure to 32 airborne workplace agents.

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Each participant was given a Genetic Risk Score (GRS) based on whether they possessed genes that increased their risk of developing rheumatoid arthritis.

Rheumatoid arthritis is distinguished by the presence or absence of anti-citrullinated protein antibodies, abbreviated as ACPA. ACPA positivity indicates a poor prognosis, with increased rates of erosive joint damage.

Nearly three-quarters of those with rheumatoid arthritis who tested positive (73%) or negative (72%) for ACPA had been exposed to at least one workplace dust or fume, compared to roughly two-thirds (67%) of the control group.

Data analysis revealed that occupational exposure was not only associated with an increased risk of developing rheumatoid arthritis, but also seemed to increase that risk by interacting with smoking and genetic susceptibility.

In particular, 17 of the 32 agents studied, including quartz, asbestos, diesel fumes, gasoline fumes, carbon monoxide, and fungicides, were strongly linked to an increased risk of developing ACPA-positive disease. Only a few agents were strongly linked to ACPA-negative disease: quartz dust (silica), asbestos, and detergents.

The risk increased in direct proportion to the number of agents and duration of exposure, with the strongest associations observed for exposures lasting 8–15 years. Men were exposed to more agents and for a longer period of time than women.

When compared to ’triple non-exposure,’ ’triple exposure’ to a workplace agent, plus smoking, plus a high GRS, was associated with a very high risk of ACPA positive disease, ranging from 16 to 68 times higher.

The risk of developing ACPA positive rheumatoid arthritis was 45 times higher for those exposed to gasoline engine exhaust fumes, 28 times higher for diesel exhaust, 68 times higher for insecticides, and 32 times higher for quartz dust (silica). The corresponding range for ACPA-negative disease was not statistically significant.

Because this is an observational study, no cause can be established. The researchers also admit that their findings have several limitations: the study relied on personal recall, and while the exposure estimates were derived using a validated method, the results can be relatively crude.

And, because there are frequently multiple workplace agents in the air at any given time, it is difficult to determine which ones might be potential triggers.

Nevertheless, the researchers conclude, "Occupational inhalable agents could act as important environmental triggers in RA development and interact with smoking and RA-risk genes, leading to excessive risk for ACPA-positive RA."

They add: "Our study emphazises the importance of occupational respiratory protections, particularly for individuals who are genetically predisposed to RA."

According to Dr. Jeffrey Sparks of Brigham and Women’s Hospital in Boston, USA, the study findings have several important implications for disease development and prevention.

"First, each occupational inhalable agent had a unique profile of the way it interacted with RA risk genes and with smoking. These unique interactions suggest that if the relationship between inhalable agents and RA is indeed causal, it may do so via distinct pathways."

Dr. Sparks comments on the findings, referring to the stronger associations found for ACPA positivity, and says that they "further support the growing belief that ACPA positive disease may be very different from ACPA negative rheumatoid arthritis."

It can be concluded that greater public health efforts are required to reduce the risk of developing rheumatoid arthritis.

Precautionary Measures to Prevent the Risk of Rheumatoid Arthritis

To begin, environmental health initiatives should aim to reduce public exposure to pollutants such as carbon monoxide and gasoline exhaust. Second, occupational health approaches should focus on reducing occupational hazards such as detergents and asbestos. Third, health promotion initiatives to reduce cigarette smoking should be maintained.

References:

1. Risk factors for the development of rheumatoid arthritis - (https://pubmed.ncbi.nlm.nih.gov/16766362/)
2. Smoking and rheumatoid arthritis - (https://pubmed.ncbi.nlm.nih.gov/25479074/)
3. Silica exposure is associated with increased risk of developing rheumatoid arthritis: results from the Swedish EIRA study - (https://pubmed.ncbi.nlm.nih.gov/15319232/)

Source-Medindia