A toxicology report on a heli-ski guide involved in a fatal avalanche March 13 found marijuana-based THC in his blood at higher than background levels.

Alaska Heliskiing guide Robert Liberman, 35, and client Nickolay Dodov, 26, were killed in the avalanche that occurred during a commercial trip by Alaska Heliskiing. Four other clients were in the group during the morning outing on a peak near the Tsirku River. Recent autopsies of the men showed both died of asphyxiation.

Liberman’s toxicology report, requested by the State of Alaska and conducted by NMS Labs of Willow Grove, Pa., found THC in Liberman’s blood at 2.8 nanograms per milliliter. According to the lab, levels of THC run between 50 and 270 ng/mL after smoking a joint, and drop to less than five nanograms after two hours.

The reporting limit for THC, the principal psychoactive ingredient in marijuana, is one nanogram per milliliter, according to the report.

Liberman’s toxicology report also found “Carboxy THC,” a metabolized form of THC, in concentrations of 16 nanograms per milliliter, where the reporting limit was five nanograms. Levels of the metabolized compound range from 10 to 101 ng/mL, 32 to 240 minutes after smoking marijuana, according to the report.

Officials with NMS Labs and the state coroner’s office each declined comment on the report.

It’s difficult to say whether the amounts of THC cited in the report would have an effect on a person, said one state official. “Whether someone would have a response to that level (cited in the report) is up to the individual,” said Dave Verbrugge, a chemist who studies analytical toxicology at the state’s public health lab.

“There’s going to be some individual variability, including factors like physiological response,” Verbrugge said.

No toxicology report was requested in Dodov’s autopsy, which was conducted by the King County coroner’s office in Washington state. Dodov was flown to Seattle immediately after the avalanche, where he was pronounced dead.

Alaska Heliskiing had no comment on the matter this week.

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