9th
![Finally convinced myself that secondhand smoke is actually a health risk.
I was always stymied by the thought that people around smokers only get a very small amount of smoke in their lungs compared to the people inhaling directly from the cigarette, and since regular smoking is certainly less than 100% lethal, how lethal could it be inhale <1% of what a smoker gets? I had always figured the amount of carcinogen that someone living with a smoker gets is so low it’s below any threshold for noticing it.
But, nope, not the case. A 2003 study from Minnesota showed that nonsmokers put in the smoking section of a casino for four hours had significantly higher levels of a tobacco-specific carcinogen metabolite in their urine than before they sat with smokers. Other studies show children with smoking parents and nonsmokers married to smokers have higher risks for lung cancer and CVD than their counterparts in smoke-free houses, but those don’t feel as conclusive to me as the Minnesota carcinogen study. Maybe parents that smoke around their kids also tend to feed them terrible food and that’s what accounts for CVD — there’s not really a way to control for that.
So, I’m beginning to think that the relationship between smoke exposure and carcinogenic effect/increased cancer risk isn’t linear but sigmoidal like a dose-response curve. It would explain a couple of counter-intuitive things like why smoking two packs a day isn’t really worse than smoking one or why even inhaling a very small fraction of what a regular smoker gets could increase risk for health problems.
I adapted this figure from a generic dose-response curve. The points I marked are somewhat arbitrary, but it assumes that smoking a pack or more per day puts you up at max carcinogenic effect, and secondhand exposure puts you towards the bottom of the curve but within a noticeable range. [Why does the curve level off? Maybe there are only so many dividing cells in your lungs and if you bathe them in smoke, putting more smoke around them throughout the day isn’t going to increase their rate of mutation.]
Anyway, this gives me a new slant on how I view smoking risk and exposure to smoke. I wonder what this graph looks like in real terms and how many cigarettes per day puts you at what risk. It’d be impossible to do a real experiment [“Hey you: smoke 8 cigarettes per day for 20 years!”], but I wonder if there’s a way to tease out some answers from existing data.
My problem with most smoking studies is all they want to establish is that there’s some risk with doing something seemingly not risky like smoking a cigarette per day. Well, there’s some risk associated with riding a bicycle through a city or even getting out of bed in the morning. I’d like someone to quantitate that risk for me so I can make decisions based on legitimate assessments of cost and benefit.](http://27.media.tumblr.com/jB1Hxnqgyoica5eoHhIj5Wepo1_400.gif)
Finally convinced myself that secondhand smoke is actually a health risk.
I was always stymied by the thought that people around smokers only get a very small amount of smoke in their lungs compared to the people inhaling directly from the cigarette, and since regular smoking is certainly less than 100% lethal, how lethal could it be inhale <1% of what a smoker gets? I had always figured the amount of carcinogen that someone living with a smoker gets is so low it’s below any threshold for noticing it.
But, nope, not the case. A 2003 study from Minnesota showed that nonsmokers put in the smoking section of a casino for four hours had significantly higher levels of a tobacco-specific carcinogen metabolite in their urine than before they sat with smokers. Other studies show children with smoking parents and nonsmokers married to smokers have higher risks for lung cancer and CVD than their counterparts in smoke-free houses, but those don’t feel as conclusive to me as the Minnesota carcinogen study. Maybe parents that smoke around their kids also tend to feed them terrible food and that’s what accounts for CVD — there’s not really a way to control for that.
So, I’m beginning to think that the relationship between smoke exposure and carcinogenic effect/increased cancer risk isn’t linear but sigmoidal like a dose-response curve. It would explain a couple of counter-intuitive things like why smoking two packs a day isn’t really worse than smoking one or why even inhaling a very small fraction of what a regular smoker gets could increase risk for health problems.
I adapted this figure from a generic dose-response curve. The points I marked are somewhat arbitrary, but it assumes that smoking a pack or more per day puts you up at max carcinogenic effect, and secondhand exposure puts you towards the bottom of the curve but within a noticeable range. [Why does the curve level off? Maybe there are only so many dividing cells in your lungs and if you bathe them in smoke, putting more smoke around them throughout the day isn’t going to increase their rate of mutation.]
Anyway, this gives me a new slant on how I view smoking risk and exposure to smoke. I wonder what this graph looks like in real terms and how many cigarettes per day puts you at what risk. It’d be impossible to do a real experiment [“Hey you: smoke 8 cigarettes per day for 20 years!”], but I wonder if there’s a way to tease out some answers from existing data.
My problem with most smoking studies is all they want to establish is that there’s some risk with doing something seemingly not risky like smoking a cigarette per day. Well, there’s some risk associated with riding a bicycle through a city or even getting out of bed in the morning. I’d like someone to quantitate that risk for me so I can make decisions based on legitimate assessments of cost and benefit.
