Work environment: Chemicals linked to cardiovascular disease

In collaboration with leading researchers, the agency reviewed studies of exposure to various chemicals on the job and the prevalence of heart disease, stroke, hypertension, and pulmonary heart disease (cor pulmonale) which causes failure of the right ventricle and blood pressure in the lungs to rise. See the table on page 12 for a summary of the results. The information can inform work environment management efforts: exposure to certain risks at Swedish workplaces may need to be monitored and addressed by testing various measures.

The SBU report analyses epidemiological studies that have linked a variety of chemicals to cardiovascular diseases. The review also examines the certainty of the correlations identified by the studies and pinpoints the areas that still lack reliable evidence. But the report does not quantify the strength of the correlations, i.e., how much more frequently a disease occurs when the work environment is exposed to a particular compound.

SBU emphasises that the impact of exposure on an individual must be assessed on a case-by-case basis. People differ when it comes to the propensity to develop various diseases. And the epidemiological studies analysed overall exposure to chemicals at the workplace level, not how individuals were exposed. SBU concludes that the research that has been evaluated cannot be expected to identify all compounds associated with cardiovascular disease. In the first place, only a limited number of compounds have been researched so far. In the second place, epidemiological studies do not typically consider compounds, which are uncommon at workplaces, that cause acute cardiovascular death. But hydrofluoric acid, as documented elsewhere, can fatally disturb the heart rhythm on skin contact alone.

The “healthy worker survivor” effect is one of many challenges faced by researchers. The idea is that certain workplaces require employees to possess unusual physical capacity. The selection may be skewed towards uncommonly healthy individuals. Compounding the dynamic is the fact that people can stay at the workplace over the long run only if they remain in good health. In other words, a snapshot of the workplace at any point in time would show that employees are just as healthy as the general population, regardless of their exposure to hazardous substances. Researchers have methodologies in their toolbox to compensate for such systematic errors.

The SBU project reviewed and eliminated more than 8,000 abstracts on the basis of study relevance and quality. That left 164 scientific articles about various chemicals and cardiovascular conditions. The conclusions are based on those particular studies, which concerned exposure to chemical compounds in the work environment, not at home or in public spaces. The new review supplements a 2015 assessment of other work environment factors that may be associated with cardiovascular disease. Previous SBU reports have also focused on symptoms of depression and exhaustion, back problems and arthrosis. [RL]

SBU’s Conclusions

SBU has systematically reviewed the epidemiological evidence exploring how exposure to chemical compounds in the workplace correlates with heart disease, pulmonary heart disease, stroke and high blood pressure.

• Heart disease: There is evidence that workplace exposure to silica dust, engine exhaust or welding fumes, all of which are common workplace exposures in Sweden today, is associated with heart disease. An association was also seen for workplace exposure to arsenic, benzopyrenes, lead, dynamite, carbon disulphide, carbon monoxide, metalworking fluids, and occupational exposure to tobacco smoke. Working with the electrolytic production of aluminium or the production of paper when the sulphate pulping process is used is associated with heart disease. An association was also found between heart disease and exposure to compounds which are no longer permitted in Swedish work environments, such as phenoxy acids containing TCDD (dioxin) or asbestos.
• Pulmonary heart disease (cor pulmonale): There is evidence that workplace exposure to silica dust or asbestos is associated with pulmonary heart disease.
• Stroke: There is evidence that workplace exposure to lead, carbon disulphide, phenoxy acids containing TCDD, as well as working in an environment where aluminium is being electrolytically produced, is associated with stroke
• High blood pressure: There is evidence that workplace exposure to asbestos or lead is associated with high blood pressure.
• There is insufficient evidence to establish if there is any difference between how vulnerable men and women are to chemical exposure in the workplace.

* The scientific evidence was considered insufficient to draw any conclusions about the association between cardiovascular disease and several additional chemicals. For example, we found that there is insufficient evidence to establish whether there is an association between occupational exposure to mercury and the incidence of heart disease, stroke or high blood pressure.

♢ = Indicates an association between exposure and condition.

⚫ = Indicates that there is insufficient evidence to draw any conclusions about the association between exposure and condition. Note that insufficient evidence does not indicate that the exposure is not harmful, rather that there is not enough information available to draw any conclusion.

⚪ = Indicates that no studies meeting our inclusion criteria were identified between exposure and cardiovascular disease. There was insufficient evidence to determine if any of the chemical exposures assessed were associated with changes in blood pressure during pregnancy.