But results of tests on the drugs which the women consumed showed they contained cannabis resin and cannabis herb, with no traces of contaminants.
One of the women had traces of benzodiazepines (tranquillisers), but, more significantly, friends told gardaí she had also sniffed aerosol deodorant.
Gardaí now suspect this may have caused her respiratory failure in conjunction with the cannabis.
The other case is less clear, with no benzodiazepines in the woman’s system, nor any reports of other substances.
It that case, gardaí are examining the possibility that synthetic cannabis — which did not come up in the tests — may have been in the cannabis she smoked.
They have also not ruled it out in the other case.
While it may turn out to have no involvement in these two cases, synthetic cannabis has begun to be found in cannabis herb and cannabis resin.
The European drugs agency, the Emcdda, this week published an analysis saying synthetic cannabis had been found in herbal cannabis.
It said: “More recently, several countries have also reported finding the substances in products that look like cannabis resin.”
It said brands such as “Bang Solid” and “Afghan Incense” were examples.
“This development is likely to be a response to the popularity of cannabis resin in many countries.”
The Emcdda said synthetic cannabis has also been detected in mixtures containing other psychoactive substances such as stimulants, hallucinogens, sedatives, and ecstasy tablets. This could be deliberate or accidental.
The Emcdda detected a record number of synthetic cannabis chemicals in 2012. The 30 new synthetic cannabis drugs identified last year bring to 84 the total number available. This is in line with a “relentless supply” of new synthetic drugs: 73 were detected in 2012, compared to 49 in 2011, and 41 in 2010.
Like with all these new drugs, the agency said little is known about the pharmacology or toxicology of synthetic cannabis. It said adverse effects were due to the substances themselves and how they are produced.
The synthetic cannabis is bought in powders manufactured in China and then shipped in bulk. The purity of the powders is very high, as high as 95%.
The bulk synthetic chemicals are mixed with or sprayed onto the herbs, typically on an industrial scale often using equipment like cement mixers and liquid solvents. Sprays can also be used on cannabis resin.
On the health consequences, the Emcdda said: “There have been numerous reports of non-fatal intoxications and a small number of deaths associated with their use.”
It added: “The active dose of some of the compounds is in the order of a few milligrams, therefore the potential for toxic effects is high.”