It’s a high one:

There are reports of lost limbs due to lack of informed consent ensured by professional interpreting. Young children commonly experience psychological trauma from being expected to play interpreter and inform mom or dad of their terminal disease; children who speak English as a second language often misinform adults about how to take their drugs. Patients withhold vital information from physicians for fear that relatives or neighbors acting as interpreters will know their private business. Doctors rely on their high school language skills and bilingual staff members are pulled away from full-time jobs, often misinterpreting for lack of training and medical vocabulary.

(via This Makes Me Sick)