Organic solvent exposure linked to more severe SSc symptoms

Men 3 times more likely to be in study's group of exposed patients

by Margarida Maia, PhD | May 23, 2023

In people with systemic sclerosis (SSc), organic solvent exposure — common among workers in industry — is more likely to be found among men and is associated with more severe disease symptoms, according to a new study.

Such symptoms primarily included gastrointestinal (GI) and kidney or renal problems.

"This is the first study reporting a higher risk of renal crisis and GI disease severity in SSc patients exposed to [organic solvents]," the researchers wrote, adding that "exposed patients were more likely to be male."

The study, "Organic Solvent Exposure and Systemic Sclerosis: A Retrospective Cohort Study Based on the Canadian Scleroderma Research Group Registry," was published as a letter in the Journal of the American Academy of Dermatology.

It is thought that SSc may arise from a combination of genetic and environmental factors. Moreover, at-work exposure to silica dust — also common in industry — may place people at a higher risk of developing the disease at a younger age and with more severe symptoms.

Less is known about organic solvent exposure. A type of liquid that can dissolve or mix with other substances, organic solvents are used in many industries as part of paints and varnishes, adhesives, and cleaning products, among other materials.

Earlier work suggested that exposure to organic solvents may increase the risk of developing SSc by up to 10 times. It is thought that organic solvents may build up in organs in the body, trigger an immune response, and damage the small blood vessels.

Now, to find out how often SSc patients are exposed to organic solvents, a team of researchers in Canada drew on data from the Canadian Scleroderma Research Group registry. The team also looked at whether being exposed to organic solvents was linked to more severe symptoms.

Of the 1,439 SSc patients in the study, about 20% (290) reported exposure to so-called chlorinated or aromatic organic solvents. Chlorinated organic solvents are typically used in dry cleaning products, among others, and aromatic solvents include products such as paint thinners.

The remaining 1,149 patients (about 80%) did not report exposure to any organic solvent.

While women are more likely than men to develop SSc, the proportion of males in the exposed group was more than three times higher than that in the unexposed group (29.7% vs. 9.2%).

Those in the exposed group also were significantly more likely to be smokers (67.9% vs. 57.3%) and to have a history of renal crisis, a severe condition in which there is a sudden rise in blood pressure and kidney failure (7% vs. 3.1%). Even after considering other factors, the odds of a renal crisis occurring were more than doubled in the exposed group.

SSc can affect the digestive system and cause gastrointestinal symptoms, commonly diarrhea, constipation, and bloating. Patients also are more likely to report difficulty swallowing and acid reflux.

The median GI-14 score, a measure of how severe GI symptoms are, was one point higher in the exposed group than in the unexposed group (4 vs. 3 points). The mean Medsger severity score of GI symptoms also was higher (2.02 vs. 1.9 points).

Researchers noted that this study was the first to reveal a link between organic solvent exposure and a higher risk of kidney problems and worse GI disease.

However, because people may have had difficulty accurately recalling their exposure, the findings of the study may be affected, the team noted. Moreover, the researchers did not have information about the levels or duration of exposure to organic solvents.

"Hence, further research is needed," they concluded.