Lead exposure has contributed more to heart disease deaths in the U.S. compared with the United Kingdom, according to new research presented this week at the American Heart Association Scientific Sessions 2022 in Chicago. Study findings also revealed that the U.S. fared better in terms of heart disease deaths linked to particulate matter — harmful particles in air pollution — when compared to the United Kingdom.The study has not been published in a peer-reviewed journal. Researchers gathered data from the 2019 Global Burden of Disease study from both countries, which in total included more than 33 million deaths over 30 years. From the data, they were able to measure how many deaths could be linked to four environmental risk factors — lead, particulate matter, secondhand smoke, and smoking. In the new study, researchers found that compared to the U.K., more people in the U.S. died of cardiovascular issues that were linked to lead exposure. In the U.K., more deaths of the same nature were linked to air pollution, compared to the U.S. Despite the differences, both environmental toxins were responsible for cardiovascular deaths in both countries, the authors noted. “We were all surprised with the results when we realized that these environmental risk factors had impacted the two countries differently,” says Anoop Titus, MD, a third-Year Internal Medicine Resident St. Vincent Hospital Worcester, Massachusetts, who led the new study. Heart disease is the leading cause of death worldwide, the World Health Organization (WHO) reports, and the number one killer of Americans, according to the Centers for Disease Control and Prevention (CDC). Pollution remains responsible for approximately 9 million deaths per year, according to a 2022 study published May 17 in The Lancet Planetary Health. This number has not changed since 2015. In the United States alone, energy-related air pollution is responsible for about 53,000 premature deaths each year, a separate study, published in May 2022 in GeoHealth, cites. The research is a step towards better understanding which policies and strategies are most effective in reducing certain environmental factors that may contribute to heart-related deaths. It also highlights often overlooked causes of heart disease that may be out of a person’s control, including toxins they’re exposed to. “If you look at the main cardiovascular disease prevention guidelines, very often they focus on lifestyle factors such as physical activity, diet, and smoking. And then they focus on managing risk factors such as diabetes, blood pressure, and lipid levels,” says Ana Navas-Acien, MD, a professor of environmental health sciences at the Columbia University Mailman School of Public Health, who was not involved with the new research. “But in the past 20 years the field of environmental cardiology has really expanded and recognizes that environmental toxins such as lead and air pollution should be included in these cardiovascular disease prevention strategies.” Lead still remains in our drinking water, soil, paint, and jewelry and it is often inhaled. According to Titus, the higher percentage of heart disease deaths attributed to lead in the U.S. is likely due to wider public exposure rather than higher concentration levels, compared to the U.K., though it’s unclear what, exactly, the differences in sources are. Once a person is exposed to lead, it replaces essential nutrients in the body, explains Dr. Naas-Acien. “Lead is similar to zinc and calcium, so it replaces these essential elements in our body and doesn’t allow for the normal cellular functions that require these elements to take place,” she says. One key function is reducing oxidative stress, which is an imbalance between free radicals and antioxidants in the body. Oxidative stress can lead to heart health issues, and preventing the body from keeping oxidative stress at bay is a key way in which exposure to lead impacts cardiovascular health, says Naas-Acien. According to the Environmental Protection Agency (EPA), air pollution also causes oxidative stress and chronic inflammation in the body. In a review published in 2020, in the International Journal of Molecular Sciences, researchers cited a growing body of evidence that links exposure to air pollutants to inflammation of the vascular system — which includes the heart, blood vessels, and blood — and oxidative stress. In addition to health issues such as cholesterol and diabetes, abnormal blood pressure is also attributed to breathing polluted air. Oxidative stress can cause changes in the structure of blood vessel walls and abnormal growth in heart chambers, according to Titus. While exposure to lead and air pollution is a notable risk factor for heart disease, he notes that smoking remains unanimously the most potent environmental risk associated with cardiovascular deaths. For this reason, not smoking is a critical step a person can take to reduce their risk, both for themselves and others who may inhale secondhand smoke. “Compared to smoking and secondhand smoke, lead and particulate matter only contribute fractionally to cardiovascular deaths,” says Titus.
