Taking clozapine has been linked to an increased risk of agranulocytosis, a condition that can make people susceptible to infections, the researchers said.

But in the 1960s, physicians linked medically prescribed potassium perchlorate to a number of deaths by aplastic anemia and severe agranulocytosis, two blood disorders.

The "burns" seen in Californian patients, who were also suffering from agranulocytosis, were the result of skin infections related to patients' compromised immunity.