Lead is a naturally occurring chemical element found in the earth’s crust. Its high density, low melting point, excellent ductility, ease of extraction and refinement, and ease of forming alloys with other metals make it widespread in numerous substances, including paints, lacquers, ceramic glazes, stained glass, crystal glass, construction, pipelines, ammunition, agricultural pesticides, gasoline, cosmetics, hair dyes, toys, and even some traditional medicines. Lead was mined and utilized as early as in ancient Rome. Its extensive use has led to major public health problems, such as contamination of the environment and exposure to the metal in humans across the world.
Lead can enter the human body through diet, skin absorption, and breathing. It is relatively easy to inhale lead-containing particles or dust, especially for those who work in lead smelting, lead-tin welding, and lead recycling for batteries. Even lead in peeling paint poses a serious problem, not to mention food and water contaminated with lead. Lead is distributed to the brain, liver, kidneys, bones, and other organs after entering the human body, and it will be stored in the bones and teeth. Lead accumulated in bones is released into the blood during pregnancy, which impacts fetal development. Infants, pregnant women, and breastfeeding mothers are more susceptible to lead than others. High concentrations of lead can affect the central nervous system and the brain, leading to cognitive decline, low learning ability, behavioral disorders, antisocial behavior and other problems in children. They can also cause anemia, hypertension, impaired kidney functions, or even death.
According to the OECD, Yemen, Afghanistan, China, Bangladesh, Haiti, Egypt, Malta, Cuba, Iran, and the Dominican Republic were the ten countries in 2017 with the highest mortality rates due to lead exposure. The figure above shows the mortality trend from such exposure over nearly three decades, with Afghanistan showing a significant decline each year from its initial position of having the highest mortality rate in the world. While the World Health Organization believes that leaded gasoline is responsible for 90% of human lead exposure, the data indicates that the global mortality rate from lead exposure has not decreased in the past 30 years, despite the switch to unleaded gasoline in most countries. In fact, the overall mortality rate increased from 115.14 deaths per million inhabitants in 1990 to 139.66 deaths per million inhabitants in 2017. In particular, China’s mortality rate saw a rise from 157.84 to 253.57 deaths per million inhabitants over the same period, a staggering 60% increase.
Incidents involving lead exposure in Taiwan are relatively minor compared with other countries. Over the past 20 years, lead exposure has been reduced substantially due to the discontinuation of leaded gasoline and leaded paint, although such incidents have occasionally been reported, such as the problems with lead pipes in 2015 and, more recently, the discovery of lead in traditional Chinese medicines. The U.S. Agency for Toxic Substances and Disease Registry listed lead as number two on its 2019 Substances Priority List, which is a clear indication of the extent of risk lead poses to health. While the U.S. currently recommends a maximum blood lead level of 5μg/dL for children, the World Health Organization has pointed out that there is no so-called “safe limit” for blood lead levels, as the metal continues to accumulate in the human body. Our recommendation is to stay away from lead exposure altogether and use only products and medications from safe and reliable sources to avoid lead poisoning.