Determination of thallium in urine, blood, and hair in illicit opioid users in Iran.

The results of the study showed that thallium concentrations in urine, blood, and hair in illicit opioid users were significantly higher than the comparable concentrations in the control group. This can be due to the use of illicit opioids adulterated with thallium. Also, this study showed long-term illicit opioid use may lead to thallium exposure. In addition, cigarette smoking was associated with increased thallium exposure.