Lead and mercury are elements (more on that below) that are also poisons, meaning taking them into the body causes significant harm. These metals are some of the oldest, and newest, poisons. The harm done to people by lead was known in ancient times and the harm done to people by mercury has been known for centuries as well.
But today, American society, and really the world, is taking a fresh look at what substances cause harm to us, and how we can finally rid ourselves of substances that impair our children and shorten our lives.
Given the renewed attention lead has received in dramatic moments of exposure, such as the water of Flint, Michigan, it seemed timely to share some of what we know about lead and mercury.
What are Elements?
If we think about all the material in the world, every big and little bit of it is made up of atoms. Some stuff is made up of only one type of atom, some is made up of atoms linked together, and most material we encounter is a mix of many arrangements of atoms.
The material made up of only type of atom is called an element, atoms bound together in one pattern are called molecules. Many elements are very, very familiar to everyone. Some examples include carbon, oxygen, gold, copper, zinc, neon, silicon, and many others. Many molecules, too, are quite well known. Every molecule is set pattern of more than one element joined together. Some examples include salt (combines the elements sodium and chlorine), water (H2O, or hydrogen and oxygen are this molecule’s elements), sugar, protein, rust.
What sort of Elements are Mercury and Lead?
All the elements share some properties. First, they are only one type of atom. The element is defined by how many protons sit in the nucleus of the atom. Consider carbon, the element of charcoal and pencil lead. This element always has 6 protons in its nucleus. Add one and it changes the element, from the black carbon, to the gas nitrogen, which accounts for about 78% of our air. Add one more proton to the nitrogen nucleus, and you get oxygen, which we breathe.
The point is that given a certain number of protons, an element can be described with set properties that do not vary, unless you change the proton count.
Mercury and lead each have a ton more protons than carbon, nitrogen, and oxygen. They have 6-8 protons per atom. Mercury has 80 and lead 82! That is a ton of protons, truly.
To put that into some perspective, on our planet, the highest number of protons in a nucleus found in nature is 92, which is the element uranium. More dramatically, once you pack in more than 82 protons in a nucleus, the elements’ nuclei start to have trouble holding it together. Protons, and neutrons, in the atom’s nucleus start splitting off on their own, releasing high energy called radiation. Mercury and lead do not do this, but many elements with more protons than they do are radiate energy as their nuclei fall apart, and we call this phenomenon radioactivity. In fact, many radioactive elements, like plutonium (proton #94), uranium (#92) and others, when their nuclei fall apart, drop their proton count to 82 and then stop decaying, that is, they turn into lead. This is one reason lead is more common in the planet than one might expect.
Both mercury and lead have a metallic look to them in pure form, and given how many protons they have, are called heavy metals.
We highly value other heavy metals, such as silver (proton #47) and gold (#80- right between mercury and lead). But these heavy metals, mercury and lead, cause more harm to our children, and us, today, than any other.
Lead and Its Uses
Lead is an interesting metal. It is heavy, it cannot corrode, but at the same time it bends easily without cracking. Not many metals are like this, so it has been used across a very large ranges of products for centuries. The result is that a tremendous amount of lead has been mined over the years and the products it has been used in have decayed, been burned, or dumped in water, leading to lead being present in soils across the world, and in many sources of water we drink. Lead still is being pumped into the air in many parts of the world where coal burning power plants fail to filter the exhaust, which can contain significant amounts of lead.
The major source of lead in the United States is the lead in the dust and soil around homes with lead paint. Lead forms chemicals that create a highly stable white pigment, making it a favored ingredient in most paints. Use of lead pigments in paints was widely used until the United States Federal government banned its use in 1978. So most homes built prior to 1978 have lead paint, most since do not. Curiously, some countries on learning that lead was poisonous, banned its use in paints in the 1920’s. The US continued to allow its use, even knowing its poisonous impacts because of the success of paint manufacturers to block the ban. Some of those companies were based in Cleveland. Lead is still in paints used in some industries, and so roads, highways, industrial structures, even cars, still have lead paint being used.
Another major source of lead in the United States once was from car exhaust. Lead in gasoline protected car and truck engines from wear and tear. Despite clear knowledge of the poisonous power of lead, efforts to eliminate it from car and truck fuel took 23 years, from 1973-1996. That’s right, lead in paint in the US was banned in 1978, but in car and truck gasoline, not fully until 1996. Even today, lead is in the gasoline used in farm equipment, and airplanes.
Lead has been widely used in the manufacture of pipes. In fact the word plumber derives from the Latin word for lead, plumbum, and the formal two letter designation for the element lead in the periodic table is Pb, short for plumbum. Lead was known to be poisonous enough that many cities banned the use of lead pipes in the 1920’s. But again, under industry pressure, use continued in pipes. National codes for the manufacture and use of pipes allowed lead in pipes through the 1980’s, and a complete ban in the use of lead in pipes and in the solder joining them was not in force in the United States until 1986. Lead was allowed to be part of home plumbing fixtures in levels, in weight, up to 8% (!) until 2014. Even today, low levels of lead are permitted in plumbing fixtures, such as faucets.
The decades of nearly universal use of lead in paints, gasoline, and pipes has caused lead to load into our soil, dust, air, and water. Lead in air tends to clear once it is no longer added to the air, but once lead was cleared from paint, it remained in soil.
The story of lead in water is also complex. As of today, cities no longer use lead pipes to deliver water from its source to our homes. Most pipes in cities also no longer use lead solder.
But, once you go from the city pipes to home pipes, the story shifts. Many older homes have leaded pipes. Even today, fixtures such as faucets contain small amounts of lead.
As dramatized by the catastrophe of Flint, Michigan, a catastrophe still not ended, acidic water dissolves lead into the water quite well, and so if a city delivers acidic water, it can leach out the lead in home pipes at an accelerated rate.
It is estimated that about 6 million homes in the United States still have lead pipes or lead solder connecting their pipes, and therefore can still deliver lead to those living in them through their drinking water and cooking.
Lead present at much higher levels in countries that have not banned its use. Consumer products containing high lead content include richly pigmented earthenware from many countries, as well as toys. The presence of pure lead in charms in toys from China is one example.
What Harm does Lead Cause?
Lead is a highly effective poison. It blocks a wide range of enzymes from working properly in the body, leading to a tremendous range of damage across many organs, especially the brain, bone marrow, and kidneys. Lead can hurt the body by being inhaled or swallowed. At sufficient levels, it blocks formation of hemoglobin, causing anemia, and can destroy kidney function. In adults, harm to reproductive system has been shown, linking lead exposure to infertility. Lead exposure in adults also leads to more heart attacks and strokes.
But it is the brain where most of the dramatic damage to humanity is seen, and it starts in childhood. Lead is known to cause the connections between nerves in the developing brain to fail to form normally, and harm the function of the nerves themselves. In children and in adults, any level of lead is associated with impaired cognition.
Or, to put it more clearly, there is no safe level of lead in the body, and in children, at any level, harm is done to the ability of the person to think.
Just to be clear, disorders of thinking include learning disabilities, ADHD, autism spectrum disorder, and overall intelligence. Exposure to lead has been implicated in the development of all these disorders and in reduced IQ.
Given the enormous attention given to the MMR vaccine when it was falsely alleged to cause autism, it remains hard to explain why an even greater reaction to continued exposure to lead is not happening when we know it does in fact play a role in the story of autism, and many other disorders of the functions of the mind.
Perhaps the most dramatic illustration of this power of lead to harm our minds is that when lead was banned in paint and gasoline, the nation’s lead levels in blood dropped dramatically. It is now known that about 60% of the drop in crime seen in the US over the last few decades was because the drop in lead in our body allowed our minds to function more normally!
Even at our current lead levels, a drop to zero would have dramatic results.
Can we Ever Be Rid of Lead?
Yes, the EPA estimates that if the United States spent $80 billion dollars, we could make our nation lead free enough to have all our children walk around with no lead in their bodies and brains. The savings in improved health and function are estimated to be $85 billion, so there would be no net cost. Given the sorts of things our nation spends its money on, and the amount our nation spends, $80 billion to protect the minds of its entire population seems more than affordable.
It reminds us of the hesitance we have had all along in protecting ourselves from this poison. We knew in the 1920’s that lead was poisonous, and very serious poison, but it took almost 60 years to stop removing it from paint, and even longer to keep it out of car and truck gasoline. Now, how much longer will it take to eliminate it all together?
Mercury and Its Uses
The human uses of mercury go back thousands of years and across most continents. The ancient Egyptians, Chinese, and Aztecs admired the flowing metal and thought ingesting it promoted health.
Mercury, like lead, combines with other atoms to form pigments that have proven deeply popular. In lead this led to its use in paints as noted above. In mercury this led to its use in cosmetics.
Mercury was the favored metal to form fillings in teeth through a material called amalgam, a combination of mercury with other metals such as silver, copper, and/or tin. This amalgam has been used for centuries, even found in teeth from the Tang dynasty of China. Fortunately, though of some concern, there are few proofs that having amalgam in your teeth leads to any significant exposure to mercury in the rest of your body. Even so, dentists are moving away from using mercury containing amalgam.
Mercury compounds are highly toxic to germs, so it was used widely as a disinfectant and preservative for many years. For many years, the orange liquid mercurochrome was applied to the cuts of kids, it is a mercury compound. The mercury compound thiomersol, was used in many immunizations causing a storm of concern that it caused autism, but the evidence is conclusive that it did not, even so, most immunizations no longer contain it. No immunization material at Advanced Pediatrics contains thiomersol.
But did you know thiomersol was widely used in mascara? It was never banned by any state in the US until Minnesota did, in 2008.
Mercury was used as a material to grab gold out of water. It is thought that the heavy contamination of the world’s oceans began with massive quantities of mercury spilled from Spanish ships mining gold in the 1500’s. The use of mercury in gold mining was not banned until the 1960’s.
Current Sources of Mercury
Mercury is part of the planet. And so when materials of the planet are burned into the air, mercury is released.
Half of all the mercury that we take into our body comes from volcanic eruptions. Of the remaining half, the vast majority of mercury comes from the burning of coal. Some is released still from gold mining outside the US, from the production of various industrial processes in the manufacture of cement, iron, and other smelters.
So, if we were to reduce the exposure to mercury to our bodies, we would need to attend to reducing the mercury in our water, and dramatically reducing the spewing of mercury into our air by the burning of coal.
Harms Caused by Mercury
As noted, there are really two mercuries that can hurt us.
The first is the element mercury, which we know can hurt the brain. Most of the element mercury in our body comes from the air. It turns out if you burn coal, you release elemental mercury in the air. And the amount is surprising, it is 50 tons of plain mercury released into the air we breathe, every year.
This mercury in the air can cause harm to developing brains. A very interesting study in Texas asked for every extra 1000 pounds of mercury released in the air in a school district in Texas, how did the incidence of autism change. The authors found that for every 1000 pounds increase in mercury release into the air, families saw an over 2% rise in the rate of autism. And, for every 10 miles away from a coal-burning plant, there was a 1.4 % drop in the rate of autism.
The other source of mercury for us is from an organic compound of methane and mercury, the methylmercury found in fish. Here the data are less clear, but there are indicators that the more methylmercury one eats in fish, the more trouble the brain has functioning. Current guidelines from the US government show that pregnant women and young children should limit methylmercury exposure by:
- Not eating any high methylmercury-containing fish, including shark, tilefish, mackeral, orange roughy, and swordfish.
- Limit intake of white tuna to 6 oz. per week.
- Limit all fish intake to 12 oz per week.
- Two heavy metals, lead and mercury sit 2 elements apart in the periodic table of elements, and both share the sad fact that they can poison people.
- Lead though eliminated from house paint and car gasoline, still is present in our water and soil. Just recently Newark declared a lead crisis and is asking people to drink bottle water.
- Lead is a terrible poison of the mind, highly damaging, so much so that harm comes at any level and rises as the level in the body rises. We could eliminate lead from our lives in the US for $50 billion by some estimates, it can be done.
- Mercury is also a known cause of harm, for the mind, heart and immune system.
- Substantially reducing harm from mercury would take ending the release of elemental mercury into the air when we burn coal, and reducing our eating high mercury-containing fish.
All the steps necessary to stop the harm done by lead and mercury are available, the question is when will we take these actions to prevent more harm to more minds and bodies?
To your health,
Dr. Arthur Lavin