March 19, 2018

The inspiration arrived in a haze at a Paul McCartney concert a few years ago in San Francisco.

"People in front of me started lighting up and then other people started lighting up," says Matthew Springer, a biologist and professor in the division of cardiology at the University of California, San Francisco. "And for a few naive split seconds I was thinking to myself, 'Hey, they can't smoke in AT&T Park! I'm sure that's not allowed.' And then I realized that it was all marijuana.".

He started thinking: San Franciscans would never tolerate those levels of cigarette smoke in a public place anymore. So why were they OK with smoke from burning pot? Did people just assume that cannabis smoke isn't harmful the way tobacco smoke is?

So far, Springer and his colleagues have published research demonstrating that second-hand smoke makes it harder for the rats' arteries to expand and allow a healthy flow of blood.

With tobacco products, this effect lasts about 30 minutes, and then the arteries recover their normal function. But if it happens over and over — as when a person is smoking cigarette after cigarette, for example — the arterial walls can become permanently damaged, and that damage can cause blood clots, heart attack or stroke.

Springer demonstrated that, at least in rats, the same physiological effect occurs after inhaling second-hand smoke from marijuana. And, the arteries take 90 minutes to recover compared to the 30 minutes with cigarette smoke. Springer's discovery about the effect on blood vessels describes just one harmful impact for non-smokers who are exposed to marijuana. State-wide sampling surveys of cannabis products sold in marijuana dispensaries have shown that cannabis products may contain dangerous bacteria or mould, or residues from pesticides and solvents.

But even if the cannabis tests clean, Springer says, smoke itself is bad for the lungs, heart and blood vessels. Other researchers are exploring the possible relationship between marijuana smoke and long-term cancer risk.

Certainly, living with a smoker is worse for your health than just going to a smoky concert hall. But, Springer says, the less you inhale any kind of smoke, the better.

"We in the public health community have been telling them for decades to avoid inhaling second-hand smoke from tobacco," Springer says. "We have not been telling them to avoid inhaling second-hand smoke from marijuana, and that's not because it's not bad for you — it's because we just haven't known. The experiments haven't been done."

Antismoking campaigners say we can't afford to wait until the research is complete. Recreational pot is already a reality.

Cynthia Hallett is the president of Americans for Non-smokers’ Rights, based in Berkeley, Calif. The organization was established in 1976, before there was a lot known about the health effects of second-hand smoke from tobacco..

Hallett says some of the arguments being made in support of cannabis remind her of the arguments made on behalf of tobacco decades ago.

"I'm seeing a parallel between this argument that, 'Gee, we just don't have a lot of science and so, therefore, let's wait and see,' " Hallett says. "The tobacco companies used to say the same thing about tobacco cigarettes."

In California, smoking cannabis is prohibited anywhere tobacco smoking is prohibited — including schools, airplanes and most workplaces. Hallett is worried that the legalization of pot could be used to erode those rules.

It starts with the premise of decriminalization, she says, and then, over time, there's "a chipping away at strong policies."

"This is the first time that I have heard second-hand smoke in reference to cannabis," admits Lee Crow, a patient-services clerk at Magnolia. "I've tried to be courteous — just common courtesy, like with anything."

The dispensary's director of clinical services, Barbara Blaser, admits she thinks a lot about second-hand smoke from cigarettes, but not pot.

"Both of my parents died of lung cancer!" she says. "I will stop a stranger and say, 'You shouldn't be smoking. My dad died of that!' "

California's Proposition 64, approved by state voters in 2016, requires that some of the state tax revenue from the sale of marijuana to be distributed to cannabis researchers. In addition, the state's Occupational Safety and Health Standards Board is examining workplace hazards that are specific to the cannabis industry.

This story is part of NPR's reporting partnership, local member stations and Kaiser Health News.

For complete story 

EXECUTIVE HIGHLIGHTS:  Colorado and Washington legalized marijuana in 2012, followed by Alaska and Oregon in 2014. The District of Columbia legalized cultivation and possession in 2014. Today’s highly potent marijuana represents a growing and significant threat to public health and safety, a threat that is amplified by a new marijuana industry intent on profiting from heavy use. State laws allowing marijuana have, in direct contradiction to federal law, permitted this industry to flourish, influencing both policies and policy makers. While the consequences of these policies will not be known for decades, early indicators are troubling. This report, reviewed by prominent scientists and researchers, serves as an evidence-based guide to what we currently observe in various states.  

For Full report see attached PDF

  • Researchers highlighted the dangers of a super-strength strain of cannabis
  • A study found 'skunk' was responsible for a quarter of psychosis cases
  • But weaker forms such as hash don't carry the same risk of mental illness 

By Stephen Adams for The Mail on Sunday PUBLISHED:  15 February 2015

Super-strength strains of cannabis are responsible for up to a quarter of new cases of psychotic mental illness, scientists will warn this week.

The potent form of the drug, known as 'skunk', is so powerful that users are three times more likely to suffer a psychotic episode than those who have never tried it.

The study, leaked to The Mail on Sunday ahead of its publication, is set to reignite the debate around Britain's drug laws, and will add weight to calls for a tougher stance towards those caught dealing or in possession of cannabis.

Scientists are warning that super-strength strains of cannabis are responsible for up to a quarter of new cases of psychotic mental illness (file image)

According to Crime Survey figures for England and Wales, over a million youngsters aged 16 to 24 smoke cannabis. Regular users are most at risk, prompting experts to warn that youngsters need to be aware of the dangers of skunk, which has been specially cultivated to be four times as strong as the cannabis smoked by previous generations.

The researchers, led by a team at the Institute of Psychiatry at King's College in London, conclude there is an 'urgent need… to inform young people about the risks of high-potency cannabis' amid a worldwide trend towards relaxing drug laws.

They will reveal there is a key difference between potent skunk strains and 'hash'. Those who used these 'weaker' forms did not seem to suffer the same increase in risks.

Psychosis is defined as a form of mental illness where people experience delusions, hallucinations, or both at the same time. Associated with conditions such as schizophrenia and bipolar disorder, some people are so badly affected that they end up committing suicide or seriously harming others because they believe they are being ordered to do so by voices in their heads.

The findings will add substance to a 2012 report by the Schizophrenia Commission, which recommended the need for 'warnings about the risks of cannabis' to mental health.

That report was chaired by schizophrenia expert Professor Sir Robin Murray, who also played a key part in the new study. It looked at cannabis use in two groups, each containing about 400 people, from 2005 to 2011. Those in the first group had all suffered 'first-episode psychosis'– a diagnosed first occurrence of the disorder.

The research appears to show a striking difference between the effects of skunk and the weaker form of cannabis, hash resin, revealing that hash seemed not to add to a person's risk of psychosis – even if smoked daily

The second group were volunteers who agreed to answer questions about themselves – including on cannabis use and mental health history – for a study. Some had suffered psychosis, others not. They were not told the nature of the project.

The academics found those in the first group were more likely to smoke cannabis daily – and to smoke skunk – than those in the second. The researchers say: 'Skunk use alone was responsible for 24 per cent of adults presenting with first-episode psychosis to the psychiatric services in South London.'

This was almost double the previous highest estimate of psychiatric cases linked to the drug – 13 per cent – from a 2002 Dutch study.

The latest research, to be published in The Lancet, concludes: 'People who used cannabis or skunk every day were roughly three times more likely to have a diagnosis of a psychotic disorder than were those who never used cannabis.'

Skunk is shorthand for around 100 strains of cannabis that contain a high proportion of tetrahydrocannabinol (THC), the drug's primary psychoactive compound. But the levels of another compound, cannabidiol – which may have anti-psychotic effects – are the reverse, high in hash and virtually zero in skunk.

The researchers speculate this could be due to the differing chemical make-up of the two forms: 'The presence of cannabidiol [in hash] might explain our results, which showed that hash users do not have any increase in risk of psychotic disorders compared with non-users.'

Michael Ellis, a Tory member of the Home Affairs Select Committee, said: 'This powerful new study illustrates that those in government and the police must be careful to send out the right message. Cannabis isn't a harmless drug: it can ruin lives.'Read more


Extensive debates continue regarding marijuana (Cannabis spp), the most commonly used illicit substance in many countries worldwide. There has been an exponential increase of cannabis studies over the past two decades but the drug's long-term effects still lack in-depth scientific data. The epigenome is a critical molecular machinery with the capacity to maintain persistent alterations of gene expression and behaviors induced by cannabinoids that have been observed across the individual's lifespan and even into the subsequent generation. Though mechanistic investigations regarding the consequences of developmental cannabis exposure remain sparse, human and animal studies have begun to reveal specific epigenetic disruptions in the brain and the periphery. In this article, we focus attention on long-term disturbances in epigenetic regulation in relation to prenatal, adolescent and parental germline cannabinoid exposure. Expanding knowledge about the protracted molecular memory could help to identify novel targets to develop preventive strategies and treatments for behaviors relevant to neuropsychiatric risks associated with developmental cannabis exposure. 

For complete article

Chris Smyth, Health Editor - February 28 2018, The Times

Cannabis has become stronger since 2008, researchers have found KING'S COLLEGE LONDON/PA

Almost all cannabis sold on British streets can cause psychosis after weaker forms were driven from the market.

The most potent “skunk” accounts for 94 per cent of all cannabis seized by police, up from half in 2005, according to the first study for almost a decade.

Dealers are thought to be pushing higher-strength products to get recreational users hooked, with the milder hashish form barely available, researchers say.

Skunk, also known as sinsemilla, is made from unpollinated cannabis and contains higher levels of THC, a psychoactive compound, than herbal marijuana or resin, also known as hashish.

Now researchers at King’s College London have analysed almost 1,000 samples 

“The increase of high-potency cannabis on the streets poses a significant hazard to users’ mental health,” said Marta Di Forti, senior author of the paper. “It’s a big worry. It’s pretty much the only kind of cannabis you can buy out there.” 

For complete article

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