In ancient times, the philosophers would gather and walk around the marketplace, the agora, and contemplate the weighty matters of the world such as the nature of justice, the ideal city, distinguishing the good from opinion, and seeking truth and knowledge. All of that walking, talking and thinking in the hot sun can make a scholar dehydrated. So, naturally, the first question these great minds would tackle is: plastic or metal? Which water bottle is best for walking and thinking?
Plastics are everywhere. The worldwide production of plastic has exploded from less than 2 million tons in 1950 to about 400 million tons in 2020. Once a plastic item has been used, it tends to stick around for a while. Plastic takes a long time to break down. For example, a plastic water bottle may take 450 years to decompose! Due to this phenomenon, plastic waste is everywhere. Only 10-15% of plastic is recycled. The rest ends up in a landfill or the ocean or is burned off. As the plastic in landfills or in the ocean breaks down, smaller particles called microplastics are produced. When plastic is burned, microplastics are released into the air. Microplastics have been found everywhere including on remote islands, in Antarctica, deep in the ocean and, increasingly, in human tissue and organs. Microplastics enter the body by two routes. Microplastics in the air are inhaled. They also enter by ingestion, for example by eating microplastic laden sea fish or drinking from plastic water bottles (even reusable water bottles). Microplastics have been found throughout the human body. They are present in high concentrations in the liver and kidneys and to lesser degrees in the hair, saliva, blood, colon and lung. Aside from just being present, do microplastics cause human disease? An important study found microplastics in atherosclerotic plaque. In the study, 58% of patients undergoing surgery for blockage in their carotid (neck) arteries had microplastics in their arteries. These patients were 4 times more likely to die, have a heart attack or stroke over the next three years compared to patients without microplastics. Another study found that coastline counties in the United States (where there is a higher exposure to ocean microplastics) had higher risks for diabetes, heart artery disease and stroke. We now know that the brain is full of microplastics as well. It was found that the level of microplastics in the brain increased by 50% from 2016 to 2024. In addition, people with higher levels of brain microplastics had more dementia and Alzheimer’s disease.
Like plastics, metals are everywhere. However, unlike plastics, our bodies require small amounts of certain metals, called essential metals, for normal metabolism. Essential metals include copper, manganese, cobalt and zinc. Small amounts of these metals are needed, but larger quantities can be toxic as are nonessential metals, such as cadmium, arsenic, lead, tungsten, uranium and mercury. Cadmium is present in tobacco smoke, meats, shellfish, and vegetables. Cadmium, tungsten, uranium, cobalt, copper and zinc come from industrial emissions, electric batteries, oil production, welding, and mining. Arsenic is found in the water and some foods. What are the health effects of metals? It has been shown that with high urinary concentrations of cadmium, tungsten, uranium and the essential metal zinc, there is an increased risk for dementia. There is no association of high urinary lead levels and dementia. In addition, there is an association between high urinary levels of cadmium, tungsten, uranium, and the essential metal cobalt and coronary calcification, a measure of plaque in the heart arteries. It is felt that these metals promote atherosclerosis through inflammation. A recent study proved the concept by showing that lead and cadmium exposure leads to increased blood levels of troponin (a measure of heart damage), proBNP (a measure of heart strain) and C reactive protein (a measure of inflammation). Lastly, a study from China showed that long-term exposure to high levels of copper, manganese, aluminum, zinc and cadmium in the drinking water increased the risk for major cardiac events (heart attacks, cardiac deaths).
What should our philosophers choose, a plastic or metal water bottle? Which one is the healthier choice? Reusable plastic water bottles add to the microplastic load. Wear and tear, repeated washing and exposure to heat damages the inner surface of the bottle, releasing microplastics into the water that is drunk. The concentration of microplastics in reusable bottles is higher than single use water bottles. Most bottles are made of polyethelene terephthalate (PET). Bisphenol A (BPA) is another chemical used to make plastic bottles. BPA has multiple adverse health effects including endocrine problems, diabetes, high blood pressure. It is best avoided. Most metal water bottles are made of stainless-steel. Stainless-steel does not wear down and release metal into the water. In addition, there are no known adverse health effects of stainless steel. When choosing a stainless-steel water bottle, make sure there is no aluminum and no lead-based solder used to seal the bottle. Lastly, make sure the plastic cap does not contain BPA.
So, don your toga, grab your stainless-steel water bottle and head to the agora to think those heavy thoughts.
