Cardiovascular disease: Environmental risk factors

• Cardiovascular diseases (CVDs) are the leading cause of death around the world.
• The mitigation of CVDs has typically focused on making individual lifestyle changes.
• However, some environmental factors — such as pollution and climate change — also significantly contribute to a person’s risk of developing CVDs.
• Experts argue that gaining a better understanding of this link is crucial to reducing the burden of CVDs.

In a new review, researchers make clear the effects of the environment on people’s risk of developing CVDs.

The research, which now appears in the journal Cardiovascular Research, also suggests mitigation strategies that could help reduce the global burden of CVDs.

About CVDs

According to the World Health Organization (WHO), CVDs are the leading cause of death globally. They claim the lives of around 17.9 million people each year.

CVDs affect the blood vessels and heart. They increase the risk of heart attack and stroke, which account for 4 out of every 5 deaths due to CVDs.

The WHO notes that a person is more likely to develop a CVD if they:

• smoke
• are not physically active
• eat a diet high in salt and low in fruits and vegetables
• drink a lot of alcohol

These behaviors can lead to hypertension, high blood sugar levels, overweight, and obesity. In turn, these conditions can increase the risk of developing a serious CVD.

A key way to reduce the risk of developing CVDs is by reversing or reducing these risk factors.

However, researchers are becoming increasingly aware of the role that environmental factors also play in the risk of developing CVDs.

Environmental factors

Medical News Today spoke with Prof. Aruni Bhatnagar, a professor of medicine and Distinguished University Scholar at the University of Louisville School of Medicine in Kentucky. Prof. Bhatnagar is an expert on CVDs.

Prof. Bhatnagar, who was not involved in the new review, said that it was crucial that we take environmental risk factors for CVDs seriously.

“Because 70–80% of CVD and diabetes [cases] are due to environmental factors, we can significantly diminish the risk of these diseases only if we identify and understand the environmental factors that contribute to them.”

– Prof. Aruni Bhatnagar

“Traditionally,” added Prof. Bhatnagar, “we have focused on reduction of risk factors by behavior modification and lifestyle changes, but these approaches have limited efficacy.”

“Moreover, individuals by themselves cannot readily avoid exposure to many […] environmental factors, such as air pollution, noise, and built environments. Therefore, a larger social effort is required to mitigate environmental risks.”

“Research on environmental causes of disease could thus help in reorienting and focusing prevention efforts and making them more effective,” suggested Prof. Bhatnagar.

Lead study author Prof. Thomas Munzel — the director of cardiology at the University Medical Center Mainz of the Johannes Gutenberg University in Germany — also spoke with MNT. He explained that this research is particularly urgent given that official guidance typically overlooks the effects of the environment on CVDs.

He highlighted the 2019 American College of Cardiology and American Heart Association (AHA) guidelines on the prevention of CVD, which do not mention environmental factors.

Prof. Munzel and colleagues also note that the WHO’s Global Action Plan for the Prevention and Control of NCDs 2013–2020 does not mention environmental factors.

According to Prof. Bhatnagar, policymakers tend to overlook environmental risk factors for CVDs because analyzing them requires a cross-disciplinary approach.

“Environmental risk factors are multifactorial and hence difficult to study,” said Prof. Bhatnagar. “Identifying and addressing these risks are mostly beyond the reach of the current medical establishment.”

“Evaluating and assessing these risks and developing interventions to mitigate them require[s] multidisciplinary teams comprising […] environmental engineers, toxicologists, cardiologists, […] sociologist[s], policymakers, and, most importantly, community stakeholders — teams that have been difficult to assemble and deploy,” said Prof. Bhatnagar.

Expert review

In response to the overlooking of environmental risk factors for CVDs, Prof. Munzel and colleagues conducted a review of the current evidence.

The researchers explain that environmental factors typically increase the risk of CVDs by increasing stress hormone signaling, oxidative stress, and inflammation. Prof. Munzel and study co-author Prof. Andreas Daiber, head of molecular cardiology at the University Medical Center Mainz, have previously demonstrated these links.

The researchers identified four key environmental factors that contribute to CVDs, which the sections below explore in more detail.

Noise pollution

The first environmental factor that increases CVD risk is noise pollution. The researchers highlight a comprehensive meta-analysis that demonstrates that for every 10 decibels of increased road noise, the risk of developing ischemic heart disease increases by a factor of 1.08.

For the researchers, the development of technologies to reduce noise pollution and improve traffic management may help mitigate these effects.

Air pollution

The second key environmental risk factor is air pollution. The researchers point to previous research that some of them had conducted.

They found that in the European Union, there are approximately 592,000 excess deaths each year due to fine particulate matter and ozone pollution. Around 41% of these deaths are attributable to ischemic heart disease and stroke.

The researchers argue that a key way to reduce air pollution is to lower the legally allowed emissions levels.

Light pollution

The third key environmental risk factor for CVDs is outdoor light pollution. The researchers note that light pollution can disrupt circadian rhythms, which can, in turn, increase the risk of CVDs.

The researchers suggest that lighting at nighttime is turned off whenever and wherever it is not essential.

Climate change

Finally, the researchers highlight the effect that climate change and global warming can have on the risk of CVDs. For example, they point out that increased global temperatures increase the likelihood of wildfires, which contribute to air pollution.

Further, Prof. Munzel and colleagues outline research that suggests that both high and low temperatures due to climate change may increase the risk of CVD mortality.

The review’s authors believe that reducing carbon emissions and introducing carbon emission fines may help mitigate the effects of climate change.

For Prof. Bhatnagar, to address the environmental factors that contribute to CVDs, researchers need to continue to highlight the significance of environmental factors to policymakers.

“First, relevant stakeholders need to understand and appreciate the magnitude of the problem,” Prof. Bhatnagar told MNT.

“The medical community and public health investigators need to identify the most important environmental contributors and then provide clear, actionable approaches to governments. And urban planners [need] to implement evidence-based strategies to diminish environmental risks,” he continued.

Prof. Bhatnagar said that individuals could take action, too.

“Individuals need to increase their awareness of the potential impact of environmental exposures — what chemicals and conditions in their communities and homes can increase their risk — then try and avoid such exposures. [This may include] avoiding going outdoors on days of high pollution and not using chemicals and household products that could be harmful.”

“Finally, a broader public consensus is needed to implement changes in policies and regulations,” concluded Prof. Bhatnagar.

Future research

For Prof. Bhatnagar, research such as the recent article by Prof. Munzel and colleagues is important, but scientists need to do more.

“[M]uch additional research is needed to identify the relative risks of different exposures, how the effects of these exposures interact, how the effects of one exposure — [for example], air pollution — is modified by another — [for example], [the] built environment or noise — which populations are most vulnerable to such exposures, which specific pathways are affected by individual environmental factors, and what are the sources of these exposures.”

“A more comprehensive and holistic assessment of environmental conditions and exposures is needed both to understand and to minimize [the] environmental threat.”

“The most important task is to understand and modify how climate change is affecting the environment and how these changes are impacting human health,” argued Prof. Bhatnagar.

Prof. Munzel agreed that research into this topic needs to be increased.

“Research all over the place dealing with the environment has to be intensified, in particular with […] more funding from the governments,” Prof. Munzel told MNT. Notably, he concluded:

“No pharmaceutical industries are interested in this topic.”

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