In which type of toxicity is Dimercaprol (BAL) contraindicated?

Dimercaprol, also known as British Anti-Lewisite (BAL), is a chelating agent primarily used in the treatment of heavy metal poisoning. However, its use is contraindicated in certain types of toxicity, particularly in cases of iron toxicity and cadmium toxicity.

In iron toxicity, dimercaprol can mobilize iron from storage sites in the body, potentially increasing free iron levels in the circulation. This can exacerbate iron-induced tissue damage and lead to further complications such as oxidative stress and cellular injury.

Similarly, in cadmium toxicity, the application of dimercaprol can lead to increased cadmium absorption into the bloodstream, amplifying the toxic effects of the metal. This risk associated with chelation therapy for cadmium indicates that treatment should be approached with caution, as it may not only fail to provide the desired detoxification but could also worsen the patient's condition.

Thus, dimercaprol is contraindicated in both iron and cadmium toxicity because it can lead to a more severe toxicological profile by enhancing the toxicity of these metals. This context solidifies why the choice indicating both cadmium and iron toxicity is the correct one regarding contraindications for the use of dimercaprol.