Any student of Chemistry will tell that the molecular formula of water is H2O.

However, if you chemically analyse the water we drink, you will find many more chemicals in addition to hydrogen and oxygen.

These chemicals can be dissolved salts like carbonates, nitrates, and so on. The water also contains minerals like calcium, magnesium, manganese, and others. Also, you can find traces of heavy metals like cadmium, mercury, lead, and arsenic.

Where do these heavy metals come from to contaminate the water? Let us see the effects these metals can have on our health. We shall also explore ways to eliminate them from the water before we consume it.

Heavy metals like mercury, lead, and arsenic are found naturally in the earth’s crust. These are natural chemicals, but they are not harmless. The heavy metals can enter our body through the food we eat and the water we drink. They accumulate inside our bodies and cause great harm.

Let us now look at these heavy metals one by one


Mercury is present in traces in the air. The principal cause of the presence of mercury is the combustion of diesel, heating oil, and jet fuel. These mercury atoms are heavy, and hence they deposit on land and water. It enters the food chain from here.

Coal-burning power plants, oil refineries, medical wastes, dental dispensaries, and cremation grounds are also sources of emission of mercury.

Also, you find mercury in its metallic form in consumer products like CFL bulbs, thermometers, medical equipment, and dental amalgam.

As mercury gets into water, the bacteria present in the water converts it into a toxic form, methylmercury. Fishes consume these bacteria. They enter our food chain when we eat these fishes. This mercury settles down and accumulates inside our body.

Arsenic had great utility in preventing the wood from rotting. People used to coat the wood with arsenic until 2002. This arsenic leeches out to the soil and enters groundwater.

Pesticides contain arsenic. When farmers spray these pesticides on the soil and over the crops, the arsenic sticks to the plants and enters its systems. Smelting industries also emit arsenic in large quantities.

Manufacturers still use arsenic in manufacturing industries like glass, semiconductors, paints, dyes, soaps, and drugs.
Seafood also contains arsenic in a mildly toxic form.

You can find lead in a variety of consumer products such as automobile components, paints, hair dyes, or even candy sweets. Almost all PVC compounds contain lead.

Drinking water can also contain lead that leeches out from pipes.

Smelting industries and pesticides emit lead.

You can also find traces of lead in the clothing and shoes of workers exposed to lead during their jobs.

Cadmium is another heavy metal that finds its way into the human body through the water we consume.

It is a by-product of mining and smelting of lead and zinc.

Plastics manufacturing industries discharge cadmium as well.

There are traces of cadmium in sewage.

We have seen how the heavy metals contaminate water and enter the human body. We shall now look at the ill-effects of these heavy metals on our bodies.

Arsenic is a carcinogenic agent while lead and mercury affect the human brain, especially children.

Exposure to lead from a very young age causes children to develop shorter attention spans. They lag behind in their studies as compared to their peers.

Children having substantial exposure to mercury experience difficulties in learning.

We shall now discuss some of the common health effects that these heavy metals have on humans.

  • Exposure to lead causes behavioral problems in individuals.
  • People exposed to lead also suffer from high blood pressure and anaemia.
  • All these heavy metals affect the functioning of the kidneys.
  • Children exposed to lead exhibit shortage of memory and learning difficulties
  • Continuous exposure to lead causes fertility problems like decreased sperm production and even miscarriage.
  • High exposure to lead causes depletion in the IQ levels.
  • Accumulation of mercury in the body can cause brain damage, blindness, and deafness.
  • People having continuous exposure to mercury experience digestive problems and suffer from kidney damage.
  • Mental retardation is also one of the ill effects of constant exposure to mercury.
  • Children exhibit a lack of proper coordination when exposed to high levels of mercury contamination.
  • Arsenic is a carcinogenic agent. Exposure to inorganic arsenic can cause skin and lung cancer.
  • It affects the peripheral nervous systems
  • Exposure to high levels of arsenic poisoning can result in the death of the individual.
  • Children exposed to arsenic from a young age show decreased level of intelligence
  • Breathing problems, nausea, vomiting, and diarrhoea are common symptoms of arsenic poisoning.
  • Continuous exposure to cadmium causes kidney problems
  • There have also been instances of people who have osteoporosis because of constant exposure to cadmium.

The solution to the problem

Consumers, as well as the Government and the industries concerned, should take adequate steps to reduce the contamination of water by these harmful heavy metals. The Government has to formulate laws that deter industries from contaminating water sources with such metal impurities.

Many Governments have prohibited use of paints that still have quantities of lead in them.

In the past, they used to treat wood with arsenic to prevent rotting. However, this practice has now phased out. However, there are still many manufacturing industries that release industrial effluents containing these harmful chemicals into our water resources.

Many countries, especially the Western countries have banned the use of mercury in thermometers. The digital thermometer has now replaced the traditional thermometer in many countries. Similarly, many countries have switched over to LED from the CFL bulbs. These fluorescent bulbs contain mercury that is harmful to human health.

Industry level actions that could reduce exposure to heavy metals

The need of the hour is the phasing out of heavy metals like arsenic, lead, and mercury from industrial products.

The burning of coal is a leading cause of mercury emission. Industries should explore cleaner sources of fuel for energy production.

Industries should move towards replacing solid-waste and medical-waste incinerators with toxicity reduction, reuse, recycling, and composting programmes.

The industries should concentrate on manufacturing more LED lights as compared to the production of the fluorescent lamps as these CFLs have a high quantity of mercury.

Healthcare industries should consider phasing out mercury from thermometers, dental amalgams, and so on by exploring alternative means.

Our responsibility in reducing exposure

1. Be careful with wood treated with preservatives like CCA (Chromated Copper Arsenate) and ACZA (Ammoniacal Copper Zinc Arsenate). It is better to remove them or paint them to reduce leeching. On the other hand, you can choose semi-transparent deck stains for deck surfaces and latex paint for other furniture.

2. Arsenic and mercury can enter our body through consumption of seafood. Specific fishes such as king mackerel, swordfish, marlin, and so on have a high content of mercury. Similarly, limit your consumption of tuna and canned ‘white’ albacore. You can consume fishes having lower mercury content such as Pacific cod, Atlantic herring, salmon, sardines, farmed catfish, and others. Pregnant women and children should avoid fish containing mercury.

3. Lead paint was standard in the olden times. Nowadays, you do not have lead paint. However, you should be careful especially if you live in houses having lead paint on its walls. Hire a professional and scrape out the paint. Use the non-lead paints available in the market today to reduce exposure to lead.

4. Lead can also enter your drinking water sources through your plumbing appliances. Hence, it is advisable to use quality water purifiers to ensure elimination of lead. The RO water purification systems are the best in this regard.

Lead paint can crack and form flakes, which can contaminate the surrounding environment.

5. PVC is another source of lead. Avoid toys made of PVC. Children especially the toddlers have a habit of chewing on their toys. Make sure that you keep these PVC toys and other items away from the reach of children.

6. It is better to avoid old dishware, especially the ceramic ones. They contain lead that can leech on to your food. Similarly, the imported food cans contain lead solder. Avoid using imported food cans.

7. These heavy metals can also make their way into your body through medications. Check out the composition of the medicines you take. Avoid consuming medicines containing lead, mercury, or arsenic.

8. Go digital when it comes to using thermostats and thermometers. Avoid the use of old thermometers containing mercury. Do not break old thermometers, CFL bulbs, and other household items containing mercury. Dispose of them using appropriate clean-up methods.

9. Farmers should be careful while using herbicides. Many herbicides such as monosodium methanearsonate (MSMA) and others contain arsenic.

10. Choose composite dental fillings instead of the mercury-contained amalgam fillings.

In any case, it is good to have an RO water purifier at home. It ensures the elimination of all these heavy metals that contaminate water. It is our responsibility to provide a healthy environment for our children.

Sources: Wikipediasaferchemicals

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