Certain chemicals have the ability to interfere with cell metabolism.
- Carcinogens include asbestos fibres, chemicals in cigarette smoke, electromagnetic radiation (UV, X-ray, microwaves, infa-red) and free radicals found in food preservatives (can be counter-acted by antioxidants).
- Mutagens that cause cancer contribute to the formation of oncogenes. These genes often code for membrane proteins that mimic growth factor receptors, stimulating growth and causing uncontrollable cell division.
- Carbon monoxide is a toxic gas that binds to haemoglobin, meaning it cannot carry the oxygen our cells require.
- Carbon monoxide, cyanide and hydrogen sulfide denature enzymes involved in metabolic pathways.
- Penicillin attacks a step in the synthesis of bacterial cell walls, acting as an antibiotic with a specific target.
- Mercury (used in thermometers) can be converted by bacteria to methyl mercury. This enters and accumulates in the food chain.
- Herbicides and insecticides kill weeds and protect plants respectively, however both contribute to chemical pollution of soil and atmosphere.
- Preservatives which are used to create long-life foods were initially used without much thought. However, they cause many different allergic reactions.
- Thalidomide was used to treat nausea in pregnant women, and their children were born with parts of their limbs missing. (Refer to image)
- Overuse of antibiotics causes resistant strains to thrive.
