SAN RAMON (KCBS)— Health officials in California are concerned about a large increase in the number of hash-oil explosions stemming from illegal labs.

As a result, East Bay Assemblywoman Catharine Baker (R-San Ramon) has proposed prohibiting anyone from buying more than 400 milliliters of butane in a month.

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Butane hash oil is a highly concentrated form of cannabis that’s illegal to make, but okay to sell in California. Experts say hash oil can have a street value of $22,000 per pound.

That’s incentive for some to undertake the dangerous task of trying to the oil with marijuana trimmings and butane, which can be odorless.

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“Either it will light up or just a spark off static electricity. Not only do they catch fire, but it can blow up houses,” said Doctor David Greenhalgh, the chief burn surgeon at UC Davis Medical Center.

Greenhalgh says he’s treating more and more hash-oil fire victims.

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“Between 2007 and 2010 we had about eight patients. Since then, it’s been about 100 patients in the last three or four years.