By Amy Johnson
News Article: https://www.cnn.com/2024/09/20/health/heavy-metal-exposure-cardiovascular-disease-wellness
Peer Reviewed Article: https://www.jacc.org/doi/10.1016/j.jacc.2024.07.020
Background
Heavy metal exposure can have serious consequences on many aspects of a person's health (1) . People can be exposed to these metals in many different ways like through smoking and other environmental sources (2). Environmental sources have been a cause for particular concern in recent years. Industries that use metals like smelting can contribute to metals in the environment. Agriculture and landfills can also be sources of metals. These metals can build up in soil and water which can lead to them entering the food chain and people becoming exposed to them (3).
Peer Reviewed Article
In recent years there has been increasing evidence of a link between environmental contaminants like metals and cardiovascular disease. One major predictor of cardiovascular events is coronary artery calcification (CAC) which had not previously been linked to metal exposure. This particular study investigated associations between levels of metal in urine and CAC. It specifically studied Cadmium, Tungsten, Uranium, Cobalt, Copper, and Zinc.
The study analyzes data from the Multi Ethnic Study of Altherosclerosis (MESA). Of these, some were excluded from this study so the final sample size was 6,418. Between 2000 and 2002 participants had medical exams where they had different things measured. They would follow up this exam four more times over a period of ten years. At the beginning of the study, participants gave urine samples and these were frozen. In 2019 these samples were analyzed using mass spectroscopy to determine metal concentrations. These concentration are reported in μg/g creatine. In the first exam, every participant received a CT scan to measure CAC. Some received this in the follow up but not all of them. This study analyzed this data with a different more sensitive method than was previously used to find CAC. This gave each patient a CAC score from 0-99. They also ran various statistical analyses and compared baseline metal levels with CAC development over time. For participants that had more than one metal sample, they also investigating how variations in metal concentration affected the data. The study also accounted for confounding variables like income.
Central Illustration Urinary Metals and Repeated Measures of Coronary Artery Calcification in the Multi-Ethnic Study of Atherosclerosis (2)
The study found a CAC score of 6.3 at baseline. This score was higher for people who had smoked or for male participants, The concentration of metals in urine also varied a lot by different age, racial, and geographic groups. For example, people in Los Angeles had higher levels for many metals and smokers had higher levels of Cadmium. Figure 1 in the study illustrates this.
Figure 1. Urinary Metal Level Distributions by Participant Characteristics (2)
They analyzed the data to find associations between urine metal concentrations and baseline CAC and change in CAC over ten years. By comparing the highest and lowest quartile of metal levels to CAC they found a lot of interesting data. For Cadmium, the highest quartile and 51% more than baseline CAC and 75% more over a ten year period. For Tungsten and Uranium they found 13% and 17% at baseline and 45% and 39% for the ten year period. For cobalt it was 29% at base line and 47% at ten years. For copper it was 15% at baseline and 33% at ten years, and for zinc it was 54% and 57% respectively.
Figure 2. Flexible Dose-Response of Urinary Metal Levels and CAC (2)
The study concludes that metals were a significant risk factor in developing cardiovascular diseases and does a call to action to decrease levels of metal pollution in the environment. They do acknowledge some limitations like most participants only doing urine samples at the first exam. For their analysis of people who did a sample and exams one and five the results were less significant because of the smaller sample size (2).
News Article
The article by Kristen Rogers opens by describing the various effects of metal exposure and then it introduces the study. It pulls a quote from several cardiologists who were not involved in the study but did provide editorial comment about the significance of the study. It then describes the issues that are caused by coronary calcification and brings in a quote from the author of the study about the study. It goes on to describe the methods and results of the study and includes a quote from a doctor about how metal exposure might be something doctors test for in the future. The article also acknowledges the limitations of the study. One is that it does not establish causation. Another is that most subjects only had their metal levels measured at the beginning of the study. It includes a quote from the author talking about how they want more resources to do a more robust study in the future. The article concludes with a call to action and for policymakers to reduce metal pollution and different ways that people can limit their metal exposure like quitting smoking (4).
Review
I am going to give this article a 10/10. I think it basically perfectly describes this study and its methodology. I found the methodology section of the study to be extremely confusing and this article did a great job summarizing it in succinct way. It includes quotes from the authors of the study and other outside medical professionals to provide balance. It also properly acknowledges the limitations of the study and opens the possibility for further research. I particularly like the call to action at the end because it talks about policy solutions and things that you can do in your personal life. There is not really much I would change about it.
References:
(1) CDC. About Lead and Other Heavy Metals and Reproductive Health. Reproductive Health and The Workplace. https://www.cdc.gov/niosh/reproductive-health/prevention/lead-metals.html.
(1)
CDC. About Lead and Other Heavy Metals and Reproductive Health. Reproductive Health and The Workplace. https://www.cdc.gov/niosh/reproductive-health/prevention/lead-metals.html.
(1)
CDC. About Lead and Other Heavy Metals and Reproductive Health. Reproductive Health and The Workplace. https://www.cdc.gov/niosh/reproductive-health/prevention/lead-metals.html.
(1)
McGraw,
K. E.; Schilling, K.; Glabonjat, R. A.; Galvez-Fernandez, M.; Arce
Domingo-Relloso; Martinez-Morata, I.; Jones, M. R.; Nigra, A.; Post, W.
S.; Kaufman, J.; Tellez-Plaza, M.; Valeri, L.; Brown, E. R.; Kronmal, R.
A.; R Graham Barr; Shea, S.; Navas-Acien, A.; Sanchez, T. R. Urinary
Metal Levels and Coronary Artery Calcification. Journal of the American College of Cardiology 2024. https://doi.org/10.1016/j.jacc.2024.07.020.
(2) McGraw,
K. E.; Schilling, K.; Glabonjat, R. A.; Galvez-Fernandez, M.; Arce
Domingo-Relloso; Martinez-Morata, I.; Jones, M. R.; Nigra, A.; Post, W.
S.; Kaufman, J.; Tellez-Plaza, M.; Valeri, L.; Brown, E. R.; Kronmal, R.
A.; R Graham Barr; Shea, S.; Navas-Acien, A.; Sanchez, T. R. Urinary
Metal Levels and Coronary Artery Calcification. Journal of the American College of Cardiology 2024. https://doi.org/10.1016/j.jacc.2024.07.020.
(1)
McGraw,
K. E.; Schilling, K.; Glabonjat, R. A.; Galvez-Fernandez, M.; Arce
Domingo-Relloso; Martinez-Morata, I.; Jones, M. R.; Nigra, A.; Post, W.
S.; Kaufman, J.; Tellez-Plaza, M.; Valeri, L.; Brown, E. R.; Kronmal, R.
A.; R Graham Barr; Shea, S.; Navas-Acien, A.; Sanchez, T. R. Urinary
Metal Levels and Coronary Artery Calcification. Journal of the American College of Cardiology 2024. https://doi.org/10.1016/j.jacc.2024.07.020.
(1)
McGraw,
K. E.; Schilling, K.; Glabonjat, R. A.; Galvez-Fernandez, M.; Arce
Domingo-Relloso; Martinez-Morata, I.; Jones, M. R.; Nigra, A.; Post, W.
S.; Kaufman, J.; Tellez-Plaza, M.; Valeri, L.; Brown, E. R.; Kronmal, R.
A.; R Graham Barr; Shea, S.; Navas-Acien, A.; Sanchez, T. R. Urinary
Metal Levels and Coronary Artery Calcification. Journal of the American College of Cardiology 2024. https://doi.org/10.1016/j.jacc.2024.07.020.
(1)
McGraw,
K. E.; Schilling, K.; Glabonjat, R. A.; Galvez-Fernandez, M.; Arce
Domingo-Relloso; Martinez-Morata, I.; Jones, M. R.; Nigra, A.; Post, W.
S.; Kaufman, J.; Tellez-Plaza, M.; Valeri, L.; Brown, E. R.; Kronmal, R.
A.; R Graham Barr; Shea, S.; Navas-Acien, A.; Sanchez, T. R. Urinary
Metal Levels and Coronary Artery Calcification. Journal of the American College of Cardiology 2024. https://doi.org/10.1016/j.jacc.2024.07.020.
(3) Briffa, J.; Sinagra, E.; Blundell, R. Heavy Metal Pollution in the Environment and Their Toxicological Effects on Humans. Heliyon 2020, 6 (9). https://doi.org/10.1016/j.heliyon.2020.e04691.
(4) Rogers, K. Heavy metal exposure could increase cardiovascular disease risk, study finds. CNN. https://www.cnn.com/2024/09/20/health/heavy-metal-exposure-cardiovascular-disease-wellness (accessed 2025-11-11).
Hi Amy, thanks for your analysis. I wasn't particularly surprised to read that heavy metals are associated with cardiovascular disease, given all of the other health impacts they're associated with, but I was surprised at the strength of the association! I agree with you that the article did a great job pulling in quotes from outside experts, and I also appreciate that they gave some recommendations for action. In particular, I really like that the study authors had the chance to explain why they had such limited measurements of metal levels, because I think it helped highlight the importance of funding research. Given that there's already a link between heavy metal exposure and negative health effects aside from cardiovascular disease, do you think this study will lead to new public health policy recommendations, or will it provide further support for existing guidelines? I also had a question about the study methods: are there any possible limitations caused by only examining participants from urban areas in the United States, as opposed to participants from rural areas and/or other countries?
ReplyDeleteI think that it will lead to more awareness of the effects of metal pollution and will support further efforts to reduce metal exposure and pollution from industry or other sources. I think only examining those people could be a possible limitation and it would be interesting to take data from a more geographically diverse group. It could be possible that people in other countries or rural areas could be exposed to different amounts of metals and studying them could give us more data about this association.
DeleteThis was a great analysis! I hadn't considered much the cardiovascular effects of heavy metals, as I had mostly heard about the neurological issues associated with them, and it's really interesting that the main issue investigated in this paper is increased calcification levels. I agree with your rating. The article does a great job describing the findings of the paper in a lot of detail, and I appreciate all the quotes they integrated. The news article says that there still needs to be research done to figure out how heavy metals cause this atherosclerosis progression; do you know if they have begun this research? That seems like it would be very interesting to know. You also mention that the concentrations of metals differ for different demographics, did the paper go into more detail about why this might be the case?
ReplyDeleteThey said they wanted more funding to do further research but I don't know if they have begun yet. They do mention that there are tons of different possible pathways the metal could take through the body. For your second question I think there are a lot of reasons. Some cities had higher concentrations of metals like Los Angeles and I think this could be because of the presence of certain industries in that city. Some of it also might be that certain people in certain demographics are more likely to work in jobs that would lead to them being exposed to heavy metals.
DeleteGood job, Amy! I am very surprised to learn that link between cardiovascular disease and metals is a field of emerging research. I would have assumed that this was previously studied due to the metals people inhale while smoking. I agree with you that the news article was very easy to understand. I like that they had a call to action at the end for policymakers to help limit metal exposure. I am curious as to what made them freeze the urine samples that they studied? How did they ensure that the accuracy of the spectroscopy measurements since sample were quite old?
ReplyDeleteI was also confused by this when I read the article. I assume that the samples were frozen so they would remain in the same state for a long period of time. If they were frozen, the metal concentrations would probably remain the same as they were when the sample was taken. To account for dilution of the sample they measured the concentration in micrograms per gram of creatinine. They also did quite a bit of calibration to ensure the measurement was accurate.
DeleteIt is definitely a significant conclusion that the authors made to link these different metals to increased risk of cardiovascular disease. Were there any specific factors that caused them to focus on the specific toxic metals that they did? I know that there are a lot of toxic metals but I was just wondering the reasoning behind their selection. My journal article focused on the exceedance of different toxic metals in soil, so it was really interesting to see the connection and why it is important to limit our exposure to these toxic metals.
ReplyDeleteI think they chose metals that had been previously associated with cardiovascular disease. I think another factor was that these metals were ones that they could easily test for in urine. They mentioned that lead was not one that they could easily test for so they did not test for it.
DeleteGreat job, Amy! I agree that the news article was very well done. It cited many credible sources and dove into great detail without getting too complicated for the average, non-scientific reader. I noticed that there was only one sentence which briefly mentioned the disproportionate impact of certain communities when describing how to limit ones exposure to metals. Additionally, it did not mention how exposure disproportionately affects certain communities or which communities are targeted. I am glad the peer review article focused so much on it though! It looks like they focused a lot of their study on the exposure levels between groups.
ReplyDeleteThat's a good observation. I think the peer reviewed article focused so much on it because they wanted to try and account for any kind of compounding variables in their analysis. I think that studying which different communities and geographic areas are the most vulnerable to heavy metal pollution could be a very interesting follow up for a different study to do.
DeleteThe news article was very well put together and had plenty of information and quotes, covering everything it needed to. While the study shows the correlation between heavy metal exposure and cardiovascular disease, I'm curious about the physiological effects as to how it works. Was there anything in the study or news article about how these metals affect our body to increase the risk of cardiovascular disease?
ReplyDeleteGreat Job, I agree with your review of the news article. It was overall very easy to read and followed the contents of the peer reviewed article very closely. Also the extra information given by the cardiologist that was interviewed was very helpful. One question I had was whether or not CAC was the only effect that these metals had on our cardiovascular system or if was just the most well known/ most serious? If not, what are the other diseases, not just cardiovascular, that these metals can cause? Also I'm very interested in how these metals can cause CAC, do they physically build up inside the arteries and heart or do they cause some kind of bodily response that leads to the calcification?
ReplyDelete