Heavy metals and your drinking water
Just like most substances, heavy metals are not harmful to the human body when taken in small doses. However, because they are not excreted as quickly as they are taken in and because they don’t decay, they tend to accumulate. It is this excessive bioacummulation property, which heavy metals are so notorious for, that make them one of the most potent classes of drinking water contaminants.
A large percentage of the heavy metals that enter your body come from the water you drink. It’s a good thing water purification can reduce that percentage considerably. No less than 95% reduction of heavy metals can be achieved by high quality water purification systems.
Harmful effects of heavy metals in water on the human body
Due to their water solubility, heavy metals easily find their way into drinking water. But many of them also have a tendency to bind tightly to proteins found within certain organs. For instance, cadmium is known to bind tightly with metallothionein, which is abundant in your liver and kidney.
So once these chemicals enter the human body, they stay there for a long time despite being highly water soluble. Then when they reach heightened levels, their harmful effects start to set in. Some heavy metals and their known harmful effects include:
Aluminum - Because it competes with calcium for absorption, heightened levels of aluminum can cause bone defects. Certain studies also associate aluminum exposure with Alzheimer’s disease.
Cadmium - Causes kidney damage; bone disorders like osteomalacia, osteoporosis, and spontaneous bone fracture; and cancer. Patients who suffer from diabetes and other kidney-affecting illnesses are more sensitive to cadmium.
Chromium - Carcinogenic and can cause allergic reactions.
Copper - Causes Wilson’s Disease, which can lead to brain and liver damage. Slightly excessive doses can cause headache, nausea, vomiting, and diarrhea, while really large doses can cause gastrointestinal bleeding, haematuria, intravascular haemolysis, and acute renal failure.
Lead - Heightened lead levels in the human body can increase blood pressure, which can subsequently result in cardiovascular diseases and even death. It also causes loss of hearing, renal defects, anemia, accelerated bone maturation, delays in neurological development and poor intellectual performance.
Mercury - Known for its high toxicity, mercury can damage the kidneys, lungs, nerves, and the brain. It can even cause death. Perhaps the largest documented industrial disaster due to heavy metals involved mercury. In Minamata Bay, Japan, 3000 people suffered deformities, other ailments and death after large volumes of mercury were dumped into the bay over a period of more than three decades (1932-1968).
Where are they coming from?
Each of these heavy metals get into our drinking water through a variety of sources. Lead, for instance, can come from plumbing materials like lead pipes, brass joints with lead, or copper pipes soldered with lead. But it can also be introduced into surface and ground water (where drinking water is mainly sourced) by other natural or man-made activities like crustal weathering, traffic emissions, industrial emissions, and highway run-offs.
Although most heavy metals originating from industrial emissions, crustal weathering, and runoffs affect only areas in the immediate locality, they can also reach far and wide.
Certain heavy metals may be transported to far-flung areas through the “grashopper effect”, a phenomena that starts when pollutants are lifted up into the atmosphere during evaporation. They are then carried to cooler regions where they descend on bodies of water during condensation. Some of them remain there and contaminate the water, while the rest are again carried off during evaporation to continue the effect.
Heavy metals exist in many natural and man-made forms. Here are some examples:
Aluminum - cars, aircraft, railway cars, and other vehicles; cans and foils; construction materials; cooking utensils; electronic transmission lines; casings of electronic consumer products; and many others.
Cadmium - volcanic emissions, batteries, electroplating, waste incineration, iron and steel production, and cement production.
Chromium - stainless steel products, superalloy products such as jet engines and gas turbines; metal coats; paint; wood preservatives; refractory equipment like blasts, cement kilns, and foundry sands for metal casting.
Copper - Electronic parts like wires, integrated circuits, and printed circuit boards; alloys; and anitmicrobial products.
Lead - plumbing materials, building constructions, bullets, fusible alloys, gasoline, paints, and batteries.
Mercury - volcanic emissions, coal-fired plants, gold mines, cement production, smelters, waste disposal, and caustic soda production.
Clearly, heavy metals are all around us. And because they can cause a variety of health problems, it is imperative to reduce the amount that goes into our drinking water.