Montreal public health is warning of an alarming increase in drug overdoses in recent weeks, tied to the presence of fentanyl mixtures. Since the end of March, health authorities say they have recorded a significant rise in the number of non-fatal overdoses in the city. Frontline workers say they have also seen the increase.“We consulted our staff when we received this notice, and indeed we have seen a tick up. We see about five overdoses a week,” said James Hughes, president and CEO of the Old Brewery Mission.Workers say rises in overdoses among opioid users are not unusual, but what…