Many consumer and industrial chemical products are harmful to the environment when used or disposed of. Some also produce hazardous byproducts during the manufacturing process itself. The good news is that it’s possible to minimise, if not eliminate, many of the detrimental effects by using alternative feedstocks and making the production process more efficient. This is one of the main goals of sustainable chemistry and green chemistry.
Reducing waste byproducts at the source is a better option than managing waste after the desired product has been utilised.
One of the best examples of this is the elimination of leaded petrol. Historically, tetraethyl lead was added to petrol to prevent engine knocking and improve efficiency. But while it may have helped to stop engine damage, tetraethyl lead posed a major threat to the environment and human health. As a result, leaded petrol was phased out from 1975 as catalytic converters became a standard feature in cars.
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Why is there a need for less hazardous chemical synthesis?
In the above example, leaded petrol was primarily phased out for health reasons. Scientists discovered that the lead in car exhausts caused chronic lead poisoning, which resulted in brain damage and decreased IQ. It also correlated with higher mortality in a population. Since lead accumulates in the body and can be biologically magnified in the food chain, there’s no safe threshold for lead exposure. 
Alongside human health, the long-term and widespread environmental impact of hazardous chemicals is also an important consideration. That’s because hazardous chemicals can affect ecological niches and cause many organisms – from soil microbes to marine organisms – to become extinct.
For instance, agricultural chemicals such as pesticides and fertilisers are unintentionally disrupting biodiversity in many areas of the world. Organochlorines used in agriculture are causing harmful mutations in many bird species, leading them to become endangered. These chemicals are thought to be responsible for eggshell thinning, which means they’re more likely to break. It also puts the chicks at greater risk of infection. 
On a positive note, less hazardous insecticides, herbicides, and fertilisers can be derived from organic sources that are biodegradable. Instead of accumulating in animal fat tissues and being biomagnified, they can easily degrade once they’re released into the environment.
Reducing the need for hazardous chemicals
One strategy for reducing the environmental and health impact of chemical products is to reduce the need for hazardous raw materials or reactants in the manufacturing process.
Alternative feedstocks can be used and alternative products can be produced. One example of this is the discontinuation of using CFCs, or chlorofluorocarbons, in aerosol sprays. CFCs are still used today as refrigerants because they’re easy to manufacture, but alternative refrigerants such as hydrocarbons propane, isobutane, and a chemical known as R-441A are now available. In some countries like the US, government regulations mandate the use of these safer alternatives.
Another strategy for minimising the need for hazardous chemicals is to reduce the demand for them. This can be achieved through awareness and education campaigns, as well as legislative actions and policy directives. A good example of this is the banning of non-biodegradable plastic bags or, as is the case in England, charging a fee for single-use carriers. Paper bags or biodegradable plastics are now commonly used in many countries as a result.
It’s clear that reducing hazardous chemicals begins with the manufacturing process, followed by the end users’ demand, and finally disposal. Just like other products, chemicals have their own life cycles, which may vary depending on the substance. This means it’s usually necessary to take a different approach to address the specific issues of each type of chemical.
Managing hazardous chemicals
Hazardous chemicals are chemicals that are harmful to both humans and the environment.
They can be grouped into the categories outlined below based on the type of hazard they pose. Of course, how best to manage hazardous chemicals depends on the substance in question.
- Asphyxiants – these are chemicals that compete with oxygen, thereby depriving the body of this vital gas. One example of this is the carbon monoxide found in car exhaust emissions. You can manage asphyxiants by storing them in secure containers. They can also be neutralised, as they are with catalytic converters.
- Corrosive chemicals – these types of chemicals can damage or dissolve tissue and metals. They’re usually highly-concentrated acids and bases.
- Irritants – any chemical that can irritate the eyes, skin, or respiratory tract is classified as an irritant. When the skin is exposed to an irritant, rashes or blisters may develop. These types of chemicals can also cause coughing if they’re inhaled. Some irritants are soluble in water, whereas others are only slightly soluble. Examples of water-soluble irritants include chromic acid and nickel chloride.
- Sensitisers – otherwise known as allergens, sensitisers can trigger an autoimmune response, which varies from person to person depending on your sensitivity. Sensitisers such as chlorine and alkalis can cause acute or chronic allergic reactions, so it’s important to know your allergies and avoid contact with these chemicals if necessary.
- Carcinogens – these chemicals can trigger mutations in human cells, which may develop into cancers. More than 200 chemicals are classified as carcinogens, including benzene, cadmium, and formaldehyde. You can prevent long term or high concentration exposure by wearing protective equipment when handling these chemicals.
- Teratogens – chemicals that can disrupt foetal development and cause birth defects are classified as teratogens. Examples of these types of chemicals include thalidomide and organic mercury compounds. Women should never ingest these chemicals.
- Reactive chemicals – these are relatively unstable chemicals that can be easily triggered by a change in temperature or pressure, the presence of water, and exposure to other compounds or mixtures, including air. Some examples of reactive chemicals include elemental sodium, nitric acid, and benzoyl peroxide. These substances should be stored in special inert containers to isolate them from other chemicals.
- Flammable chemicals – any chemical that has a high vapour pressure, is highly volatile, and burns easily when ignited or exposed to heat is classified as flammable. Examples include many types of hydrocarbons and alcohols. It’s important to store flammable chemicals in a safe location away from ignition sources.
How do you identify hazardous chemicals?
It’s usually easy to identify hazardous chemicals at a laboratory or chemical factory because their containers have labels that indicate whether they’re corrosive, poisonous, carcinogenic, or flammable. They also have corresponding safety data sheets, either as part of the label or as a separate file.
However, if the chemical is unlabelled, there are some simple tests you can perform to help you identify whether it’s hazardous. You might, for example, carry out a flame test using a small sample, or you may want to do a smell test. There are also more advanced laboratory instruments that you can use, such as mass spectrometers. When in doubt, always take all the necessary precautions.
How can you reduce the risk of hazardous chemicals?
Laboratories and chemical factories have protocols on how to reduce the risk of hazardous chemicals.
Workers are required to wear protective clothing, goggles, and gloves. Hazardous chemicals should also be stored in accordance with the relevant guidelines, such as at the appropriate temperature and pressure.
Minimising hazardous chemical exposure
Minimising your exposure to hazardous chemicals is relatively straightforward. For starters, never handle a chemical that isn’t part of your tasks at work. If you do need to deal with hazardous substances, it’s essential to wear the appropriate PPE and follow the correct protocols in handling and disposing of such chemicals. You should also ensure that the work area is properly ventilated.
