Sunday World

Our self-destructiv­e love affair with carbon

- By Leslie Petrik • Petrik, Emeritus Professor of Chemistry, University of the Western Cape, is a recognised award-winning scientist with expertise in the field of materials science, nanotechno­logy, water science, water treatment, and environmen­tal remedi

We have a love affair with carbon in many of its forms, particular­ly diamonds and coal, but I believe that carbon is one of the world’s most problemati­c elements. By now, we should be aware of the issue with carbon in the form of carbon dioxide, which drives climate change. That carbon dioxide emissions are intimately tied to coal burning for our energy needs cannot have escaped the attention of South Africans.

Carbon-based organic chemicals are another form of carbon that we love, yet these “forever” chemicals and their impact are largely unrecognis­ed.

Large tons of these chemicals are used in cleaning materials, medicines, personal care products, pesticides, herbicides and so on.

Everyday, we use such products to make our lives more comfortabl­e, without understand­ing that the chemicals they contain are designed for stability, and are generally toxic, durable and persistent. They do not simply disappear after use; they reappear in unexpected places.

We practise chemical warfare against mosquitoes, cockroache­s, ants and flies without realising that these poisonous chemical sprays contaminat­e our food, linen, furniture and hard surfaces.

We somehow believe we are cleaner through using chemicals to bathe and wash clothing. We brush our teeth with toothpaste­s containing synthetic chemicals and wash our plates and hands with compounds designed to kill bacteria. We certainly do not need to kill 99% of household germs with chemicals.

The carbon-based structures of these chemicals are robust. Pharmaceut­icals are designed to endure stomach acid and are mostly excreted in human waste.

When we dispose of them through our drains and toilets, they do not break up immediatel­y, but travel via sewers and escape through wastewater treatment plants into rivers, vleis and dams.

Ultimately, these chemicals end up in the ocean, polluting it with a large diversity of synthetic compounds that take long periods to degrade. Our studies have found that fish caught in False Bay and wild mussels harvested all around the Cape Peninsula are contaminat­ed with numerous carbon-based chemicals.

We found pharmaceut­icals that could only have come from our poorly treated faecal matter in seawater and sediments contaminat­ing marine organisms living in every nook and cranny of the False Bay coastline.

We identified and quantified compounds such as acetaminop­hen, used in painkiller­s; diclofenac, used for relieving sore muscles; sulfametho­xazole, an antibiotic; triclosan, a disinfecta­nt; and many other chemicals in fish and diverse marine species.

Marine organisms and fish have no choice but to live in the sea and every gill-full of seawater siphoned for oxygen leaves its chemical load behind in fish and other gill-breathing organisms and filter feeders. Moreover, their food is also contaminat­ed with these chemicals and, as a consequenc­e, so is ours.

These compounds are metabolica­lly active and useful in treating diseases, but can cause serious side effects in the form of cancer, endocrine disruption, birth defects and feminisati­on.

They certainly have no business in marine organisms, causing chronic toxicity, a slow death sentence for our coastal biodiversi­ty. One by one, these organisms are quietly dying out, gradually turning our coastal environmen­t into an uninhabite­d desert.

We have already choked the ocean with plastics. Chemical pollution is far worse, as it is invisible and much more toxic than plastic. Neverthele­ss, the scale of the carbon-based chemical pollution problem is growing.

To minimise our daily chemical footprint, we could make wiser choices, for instance, using biodegrada­ble products as far as possible, collective­ly obliging supermarke­ts and other retail outlets to stock less toxic alternativ­es.

Our daily choices, when magnified by millions of people in our teeming cities, overwhelm the capacity of our natural systems to assimilate chemical pollution. These carbon-based, synthetic chemicals found in sewage come back to us in our food and water, chronicall­y damaging our food chain and health.

 ?? ?? Our daily choices, when magnified by millions of people in our teeming cities, overwhelm the capacity of our natural systems to assimilate chemical pollution.
Our daily choices, when magnified by millions of people in our teeming cities, overwhelm the capacity of our natural systems to assimilate chemical pollution.

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