The substances that can affect your hearing
Pernilla Videhult Pierre researches how different substances can damage hearing - or provide protection in emergency situations. This article is part of an in-depth feature from KI's popular science magazine Medicinsk Vetenskap.
Pernilla Videhult Pierre is a pharmacist and researcher at the Department of Clinical Science, Intervention and Technology at Karolinska Institutet.
Text: Annika Lund for the magazine Medicinsk Vetenskap nr 2, 2023 / Spotlight on hearing loss
Which medicines and chemicals can damage hearing?
“The cancer medicine cisplatin and the antibiotic gentamicin are known examples of medicinal products that can cause permanent hearing damage, but there are others. There are also a number of chemicals that can damage hearing if you are exposed to them via inhalation or through the skin. Carbon monoxide is one example. Some chemicals have an enhanced damaging effect on hearing when combined with noise. One such example is styrene, which is used in the production of plastics.”
How does it work?
“In simple terms, these substances create oxidative stress and inflammation that damage the hair cells in the inner ear's cochlea. Some of them also seem to affect the so-called acoustic reflex, a reflex triggered by loud noises. It causes the ossicles of the middle ear to move a little slower and then the sound is not transmitted as strongly, so the inner ear is protected from incoming sound for a while. When this reflex no longer works, the ear becomes more sensitive to noise.”
How can hearing be protected in these cases?
“We have shown in experiments with guinea pigs that inhaling hydrogen gas immediately after an acute noise injury protects hearing. We envision that in the long term, there could be hydrogen containers with inhalation masks in some workplaces, just as there are eye showers where employees are at risk of getting harmful substances in their eyes. But we need to know more, such as how much hydrogen is needed before we get there. In the case of cisplatin, we know that the medicinal product sodium thiosulfate can alleviate hearing damage. But unfortunately, the effect on cancer treatment can also be diminished. We have shown in guinea pigs that giving sodium thiosulfate in the middle ear reduces the risk of hearing damage but the effect on cancer remains. Administering medicines to the middle ear to treat the inner ear is an approach we strongly believe in.”