Annals of Indian Academy of Neurology
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Year : 2022  |  Volume : 25  |  Issue : 6  |  Page : 997-998

Metal exposure and stroke: Are we concerned enough?

Department of Neurology, Apollo Multispecialty Hospitals, Kolkata, West Bengal, India

Date of Submission13-Nov-2022
Date of Acceptance13-Nov-2022
Date of Web Publication23-Nov-2022

Correspondence Address:
Debabrata Chakraborty
64/4A/9, Beliaghata Main Road, Kolkata - 700 010, West Bengal
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/aian.aian_912_22

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How to cite this article:
Chakraborty D. Metal exposure and stroke: Are we concerned enough?. Ann Indian Acad Neurol 2022;25:997-8

How to cite this URL:
Chakraborty D. Metal exposure and stroke: Are we concerned enough?. Ann Indian Acad Neurol [serial online] 2022 [cited 2023 Feb 6];25:997-8. Available from:

Stroke is now a global epidemic. It is the major cause of disability worldwide and the second leading cause of death.[1]

Risk factors of stroke are divided into nonmodifiable and modifiable. As nonmodifiable risk factors cannot be influenced upon, we need to make sure that we do not miss any attempt to adapt the modifiable risk factors in our favor.

With pollution of the environment and industrialization, people are getting more environmental and occupational exposure to these toxins. These pollutants have been contributing to various conditions but most important is stroke.

Thus, environmental toxin exposure (especially metal poisoning) is another modifiable risk factor for stroke which we need to be carefully aware of. Arsenic (As), lead (Pb), cadmium (Cd), and mercury (Hg)–constitute examples of heavy metal pollutants.[2],[3]

People are exposed to elevated levels of arsenic through drinking/using contaminated water, irrigation of crops, eating contaminated food, industrial processes, and smoking tobacco.[4]

After ingestion, typical methylation of inorganic arsenic results up to 75% and up to 15% concentrations of dimethylarsinic acid and monomethylarsonic acid (MMA), respectively.[5] Those with a higher concentration of MMA (over 15%) are poor methylators and are at a higher risk of hypertension, heart disease, atherosclerosis, peripheral vascular disease, and cancer.[5]

Hg exposure mainly occurs through the consumption of fish.[6] With the toxicity, there is an increased risk of atherosclerosis, cerebrovascular events, coronary heart disease, hypertension, myocardial infarction and renal dysfunction.[6] Chronic exposure to Hg increases inflammation, oxidative stress, and reduces bioavailability of nitric oxide.[6]

Cd exposure mainly occurs through the consumption of contaminated water and food. It also occurs via inhalation of polluted air and smoke.[7]

Sources of lead poisoning include contaminated air, soil and water. Adults who work with batteries, work in auto repair shops and do home renovations get exposed to lead. Lead-contaminated dust and lead-based paint and older buildings are sources of lead poisoning.[8]

Cd and Pb increase inflammation, oxidative stress, endothelial dysfunction and down-regulation of nitric oxide generation. They increase risk of peripheral arterial disease and atherosclerosis.[8]

Aluminum is also noted to have role in vascular disease. It has been widely used as food additives, in medication, water purification, and many other industrial products.[9] Aluminum has a high affinity with endothelial cells and could be strongly accumulated in cerebral arteries and aorta.[9] It can induce vascular dysfunction and increase blood pressure. The increased vascular cyclooxygenase-2 (COX-2)-derived prostanoids and reactive oxygen species (ROS) are important mediators of vascular dysfunction after aluminum exposure.[9]

Interestingly, on the contrary, they found lower concentrations of iron and selenium may increase the risk of stroke.[9]

Thus, every metal exposure has its own role to play as a risk factor for stroke. The duration and severity of exposure are also important.

Every metal has its own characteristics of toxicity also in context to accumulation inside body, as, for example, cadmium remains in the body for long (half-life for three decades).[10] Smoking and alcohol consumption also increases blood level of heavy metals in people.[10]

In many parts of the world, the economy significantly depends on metal industries and we should know how to deal with their toxic exposure (besides our attempt to avoid it). We need to identify a universally acceptable method for detection of the blood and urinary level of the metal. So that we can confidently measure and restrict exposure of the culprit metal to an individual. This will help prevent catastrophic side effects in the future. Last, genetic background may influence metabolism of heavy metal (as for example poor methylators in arsenic poisoning) and thus outcome may vary. Thus, in the future, identification of these susceptible individuals will help deal with such situations more confidently. At the next level, we need to correlate the individual metal toxicity with the mechanism of stroke (large artery large-artery atherosclerosis/cardio embolism/small-vessel occlusion/dual mechanism); so that management of stroke can be even better.

   References Top

Katan M, Luft A. Global burden of stroke. Semin Neurol 2018;38:208-11.  Back to cited text no. 1
Solenkova NV, Newman JD, Berger JS, Thurston G, Hochman JS, Lamas GA. Metal pollutants and cardiovascular disease: Mechanisms and consequences of exposure. Am Heart J 2014;168:812-22.  Back to cited text no. 2
Wen Y, Huang S, Zhang Y, Zhang H, Zhou L, Li D, et al. Associations of multiple plasma metals with the risk of ischemic stroke: A case-control study. Environ Int 2019;125:125-34.  Back to cited text no. 3
Chung J-Y, Yu S-D, Hong Y-S. Environmental source of arsenic exposure. J Prev Med Public Health 2014;47:253-7.  Back to cited text no. 4
Steinmaus C, Yuan Y, Kalman D, Rey OA, Skibola CF, Dauphine D, et al. Individual differences in arsenic metabolism and lung cancer in a case-control study in Cordoba, Argentina. Toxicol Appl Pharmacol 2010;247:138-45.  Back to cited text no. 5
Houston MC. Role of mercury toxicity in hypertension, cardiovascular disease, and stroke. J Clin Hypertens (Greenwich) 2011;13:621-7.  Back to cited text no. 6
Hogervorst J, Plusquin M, Vangronsveld J, Nawrot T, Cuypers A, Van Hecke E, et al. House dust as possible route of environmental exposure to cadmium and lead in the adult general population. Environ Res 2007;103:30-7.  Back to cited text no. 7
Navas-Acien A, Selvin E, Sharrett AR, Calderon-Aranda E, Silbergeld E, Guallar E. Lead, cadmium, smoking, and increased risk of peripheral arterial disease. Circulation 2004;109:3196-201.  Back to cited text no. 8
Wen Y, Huanga S, Zhangc Y, Zhangd H, Zhoue L, Li D, et al. Associations of multiple plasma metals with the risk of ischemic stroke: A case-control study. Environ Int 2019;125:125-34.  Back to cited text no. 9
Yen C-C, Chen H-H, Hsu Y-T, Tseng C-J, Lin C-H. Effects of heavy metals in acute ischemic stroke patients: A cross-sectional study. Medicine (Baltimore) 2022;101:e28973.  Back to cited text no. 10


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