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Potential causes of methamphetamine-related keratitis can be divided into four categories resulting from (a) direct pharmacologic and physical effects of methamphetamine; (b) the toxic effects of diluting or "cutting" agents such as lidocaine and quinine; (c) effects related to the route of drug administration (intravenous, inhalation, smoking); and (d) manufacture-related effects of exposure to unintentional caustic contaminants in the final product.
 ( adverse event: related ,  keratitis: Effect, methamphetamine: Treatment, methamphetamine: Treatment.Drug) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: adverse event,potential therapeutic event, Arguments type: Treatment.Disorder,Treatment.Time_elapsed,Treatment.Dosage,Subject.Race,Treatment.Drug,Treatment.Route,Subject.Disorder,Treatment.Freq,Treatment,Effect,Subject.Population,Treatment.Duration,Combination.Drug,Subject,Subject.Age,Subject.Gender. 
Text: {0} 
Answer:
 ( adverse event: related ,  keratitis: Effect, methamphetamine: Treatment, methamphetamine: Treatment.Drug) 