Post by thread:[EE:] Blood Alcohol Test Error

Hi all, I'm just reading about BAC testing device (used roadside by police) on How Stuff Works. Something that troubles me is, how accurate are these devices? Like if the limit is 0.08 and one blew 0.09, they would be considered Driving Under the Influence, but what's there % error with these devices. Surely they can't be accurate enough to guarantee that someone who blew 0.09 doesn't actually have a BAC of 0.07 right? Not that I drive drunk or anything, but it just seems like something where non-chemists are using very technical devices like BAC testers couldn't be accurate enough to discern 0.01 difference in BAC. Anyone care to comment? Cheers ===== MJ Brush LeftClick.ca Internet Media Services mbrush@[NOSPAM]leftclick.ca ______________________________________________________________________ Post your free ad now! http://personals.yahoo.ca -- http://www.piclist.com hint: To leave the PICList spam_OUTpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

Matthew Brush wrote: {Quote hidden}> Hi all, > > I'm just reading about BAC testing device (used > roadside by police) on How Stuff Works. Something > that troubles me is, how accurate are these devices? > Like if the limit is 0.08 and one blew 0.09, they > would be considered Driving Under the Influence, but > what's there % error with these devices. Surely they > can't be accurate enough to guarantee that someone who > blew 0.09 doesn't actually have a BAC of 0.07 right? > > Not that I drive drunk or anything, but it just seems > like something where non-chemists are using very > technical devices like BAC testers couldn't be > accurate enough to discern 0.01 difference in BAC. > > Anyone care to comment? > > Cheers > > ===== > MJ Brush > LeftClick.ca Internet Media Services > mbrush@[NOSPAM]leftclick.ca > > ______________________________________________________________________ > Post your free ad now! http://personals.yahoo.ca > > -- > http://www.piclist.com hint: To leave the PICList > .....piclist-unsubscribe-requestKILLspam@spam@mitvma.mit.edu > > Ahh yes, Google is our friend..... http://www2.potsdam.edu/alcohol-info/DrivingIssues/1055505643.html Jim -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestKILLspammitvma.mit.edu

There is tolerance in every test ever devised. But I think that the state law considered the error tolerance when they wrote the law, as every person who challenges the meter is allowed to provide blood for a very accurate blood-based test. The problem is that once they have that, they can steal some for a DNA test, a drug screen, an HIV test, and about 100 other things that you REALLY don't want them to test for, right? I work for 'em, but I gotta tell ya, they rarely tell you the whole story about anything. I'd just take the breath test then pay the fine. --Bob Matthew Brush wrote: {Quote hidden}> Hi all, > > I'm just reading about BAC testing device (used > roadside by police) on How Stuff Works. Something > that troubles me is, how accurate are these devices? > Like if the limit is 0.08 and one blew 0.09, they > would be considered Driving Under the Influence, but > what's there % error with these devices. Surely they > can't be accurate enough to guarantee that someone who > blew 0.09 doesn't actually have a BAC of 0.07 right? > > Not that I drive drunk or anything, but it just seems > like something where non-chemists are using very > technical devices like BAC testers couldn't be > accurate enough to discern 0.01 difference in BAC. > > Anyone care to comment? > > Cheers > > ===== > MJ Brush > LeftClick.ca Internet Media Services > mbrush@[NOSPAM]leftclick.ca > > ______________________________________________________________________ > Post your free ad now! http://personals.yahoo.ca > > -- > http://www.piclist.com hint: To leave the PICList > piclist-unsubscribe-requestspam_OUTmitvma.mit.edu > > -- Replier: Most attachments rejected -------------- Bob Axtell PIC Hardware & Firmware Dev http://beam.to/baxtell 1-520-219-2363 -- http://www.piclist.com hint: To leave the PICList @spam@piclist-unsubscribe-requestKILLspammitvma.mit.edu

> I'm just reading about BAC testing device (used > roadside by police) on How Stuff Works. Something > that troubles me is, how accurate are these devices? > Like if the limit is 0.08 and one blew 0.09, they > would be considered Driving Under the Influence, but > what's there % error with these devices. Surely they > can't be accurate enough to guarantee that someone who > blew 0.09 doesn't actually have a BAC of 0.07 right? You COULD take the line (but most wouldn't) that - "actual" blood alcohol and that indicated by the test are not certain to be 100% identical and the sample itself could be high or low by a certain margin. - and add to this that there is an error margin in the instrumentation and testing method and you get an even wider spread than just measurement error. - then you add the variability in effect of alcohol on various people and see that some are much more controlled than others at the same alcohol reading, and note that the aim of the limit is (presumably) to set some sort of safety limit. - and you could note that women seem to be somewhat more affected by alcohol by men (but this may or may not be solely or mainly related to weight) - and note that some people are genetically more affected by alcohol than others and out of all this conclude that trying to stand *right on the very edge* of the crumbling cliff edge, *right on the very edge* of the windy platform when the Shinkansen/TUV/... was coming ("Mind the gap" (only UK readers will understand :-) )), *right on the very edge*of the motorway lane while changing a tyre, ... was unwise, and conclude that in real life all edges are ill defined, and that it is reasonable to add a reasonable margin of error in all such cases so that you have very little chance of falling / being hit by a train / hit by a car / failing an alcohol test. But, as I said, for some reason or other, some probably feel that that line is unreasonable in this case :-) (JG will now probably ask me why I am so against individual rights and liberties and wishing to impose my will on others. Maybe I should stand further away from the edge :-) ). Russell McMahon PS: One may also guess, perhaps incorrectly, that testers are built with an allowance for margin of error so that their results can be defended in court. -- http://www.piclist.com hint: To leave the PICList RemoveMEpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

On Jul 4, 2004, at 5:20 PM, Russell McMahon wrote: > and out of all this conclude that trying to stand *right on the very > edge* of the crumbling cliff edge... All the stuff I've seen pretty much indicates that by the time the breathalyzer test shows you anywhere NEAR the legal limit, you're REALLY drunk. Staggering around and giggling drunk. (for instance, see that episode of Mythbusters, where they tried assorted folk remedies to beat the breathalyzer, where one of their problems was getting up to the limit in the first place (IIRC, it took about 12 drinks.) I've also seen interesting things elsewhere (drivers ed?) where people tried to drive an obstacle course after reaching the limit. This wound up with the driver mowing down all the cones, smashing into the dummy, leaping out of the car and running around with his arms in the air yelling 'ya hooooo!') The point where you really shouldn't be driving is WAY before that... (of course, this is what "they" want you to believe, right?) Besides, there's no particular reason to think that detecting .01% differences in BAL should be difficult. That's the region where the test is designed to work. It's not like it has to cover 0 to 1% with 16 bits of accuraccy. Just being good enough to agree with a blood test over the limit +/- 12% (.07 - .09?) most of the time is fine. (but it doesn't take into account people's different reactions to alcohol, nor their different "starting points" for coordination and reaction time. I got kicked of a jury once for mentioning that...) (it's a bit like the chlorine tests for swimming pools, which measure 0 to 5 ppm of chlorine. It's not really hard, just cause it's a small amount. But the tests do a lousy job measuring MORE than 5 ppm...) BillW -- http://www.piclist.com hint: To leave the PICList spamBeGonepiclist-unsubscribe-requestspamBeGonemitvma.mit.edu

At 05:00 PM 7/4/2004 -0700, you wrote: >There is tolerance in every test ever devised. > >But I think that the state law considered the error tolerance when they >wrote the law, as every person who challenges the meter is allowed to >provide blood for a very accurate blood-based test. The problem is that >once they have that, they can steal some for a DNA test, a drug screen, >an HIV test, and about 100 other things that you REALLY don't want them >to test for, right? > >I work for 'em, but I gotta tell ya, they rarely tell you the whole >story about anything. I'd just take the breath test then pay the fine. > >--Bob From what I've read, in Ontario the penalties for driving under the influence have become EXTREMELY punitive. Your insurance will skyrocket by thousands of dollars, or you may not be able to get it at all, and you HAVE to install a breathalyzer interlock on your car for $thousands of dollars after the mandatory year or so of licence revocation expires- for at least another year. It sounds like exceeding 0.08 would be a real life-altering experience. Intentionally so, of course, but it's far more than just shelling out a few hundred bucks or even a couple thousand dollars (the maximum for a first offence) for a fine. Six months in jail for a first offense is possible, and also they remove your licence on the spot (before you are convicted) for 90 days under administrative rules (before conviction and the one year + one year interlock minimum kicks in) www.mto.gov.on.ca/english/safety/impaired/interlock/ http://www.mto.gov.on.ca/english/safety/impaired/breaklaw/breaklaw.htm They estimate the total cost in the $15K range, minimum. It's also a criminal code offence and can result in being turned back at international borders, which is becoming more likely as such information is being shared between governments more readily.. What I don't know is whether the police are giving people who are close to the limit a bit of a break, knowing how it could totally screw up their lives. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" speffEraseME.....interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com -- http://www.piclist.com hint: To leave the PICList EraseMEpiclist-unsubscribe-requestmitvma.mit.edu

> From: Matthew Brush[SMTP:RemoveMEmatthewbrushEraseMEEraseMEYAHOO.CA] > Sent: Sunday, July 04, 2004 9:23 PM > To: RemoveMEPICLISTspam_OUTKILLspamMITVMA.MIT.EDU > Subject: Re: [EE:] Blood Alcohol Test Error >>www2.potsdam.edu/alcohol-info/DrivingIssues/1055505643.html >> >> Jim >> > It sound like from this article that someone trying to > cover up their breath with Mouthwash (which contains > ethyl alcohol I think) would most definitively blow > over on a BAC test. Maybe even some of the new super > strong gums would do that too. . . . > Cheers > ===== > MJ Brush > LeftClick.ca Internet Media Services > mbrush@[NOSPAM]leftclick.ca The theory behind the breath test is that any alcohol in the mouth itself will evaporate quickly and disappear. I believe that they ask you to inhale and exhale several times before taking the test. (I have never been asked to take the test, but I have read that.) This is to guarantee that any such residual alcohol will not affect the measurement. Alcohol that is swallowed is absorbed into the blood stream through the stomach wall and is then circulated. This preserves the alcohol from immediate evaporation. As it passes through the lungs on each pass, some fraction of the alcohol will pass back into the air which is exhaled, causing a slow release of alcohol through the breath. The same phenomenon occurs after eating certain foods, like onions, which contain aromatic oils. One's breath will continue to smell like onions until all of the oils are metabolized. This process takes a relatively long time and there is nothing that will hurry it up. The percent of alcohol in the blood is probably measured by comparing the concentration of alcohol in the breath sample with that of some other component in the breath, such as carbon dioxide. The ratio of the measurements is the actual indication. This would be similar to measuring pollution emissions from a car's exhaust by also measuring the CO2 content and comparing. John Power -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

--- Ian Hooper <RemoveMEnoisyTakeThisOuTspamROGERS.COM> wrote: > Of course in Ontario, even if you don't "blow over" > .08, you can still be > charged with impaired. Just not worth the risk, been > there done that, and > yes $5k /year insurance for a while after that. > Don't drink and drive eh?! > > ian Yep, in Ontario it's Zero Tolerance. If you get pulled over and you have even 0.04 or whatever (or you said you had one beer) they can pull your license for 12 hours if they deem it necessary. On the other hand, my cousin has been charged with DUI several times now and it wasn't until the last one that they finally took his license away for a substantial period of time (6mo. - 1yr.). Before that it was just 90 days or 60 days or something. The sad part is, in 6 months when he gets his license back, he'll get wasted and drive again, jeeze, he still does it and he doesn't even have his license right now. Hopefully no one gets hurt and the cops take it away for good. Some people can't handle the responsibility of steering a 2000 pound hunk of metal flying at 50km/h. Anyway, my $0.02 ... as an Ontarioan(sp?) Cheers ===== MJ Brush LeftClick.ca Internet Media Services mbrush@[NOSPAM]leftclick.ca ______________________________________________________________________ Post your free ad now! http://personals.yahoo.ca -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

yeah, i loved that show, until they were talking about cell phones blowing up gasoline pumps. now i doubt that cell phones are blowing up gasoline pumps, but as a demonstration they tried to cause a fuel air explosion in a Plexiglas box, they couldn't! obviously these guys are not well versed in the scientific method and don't bother to research things enough, or they would have know that success would probably have permanently deafened them, not to mention the property damage. now if they had tried it with hydrogen or acetylene, they probably would have managed as both of those have a wide range of explosive mixture with air, while gasoline apparently has a fairly narrow range (i know some things have less than a 10% explosive range when mixed with air, and some will hardly burn if there's a little too much)... i suspect that their equipment may have been out of spec etc. either that or the state issued rules of the road books and drivers ed greatly exaggerate how few drinks it takes to hit that limit. i've had a lot more than the alleged limit, and while i didn't drive, i'm sure i could have to some extent. timing is also a critical and often overlooked issue, alcohol on average takes 45 minutes to peak intoxication, meaning you may be fine when you leave, but if you just had 2 or 3 shots in the last 10 minutes you could be very drunk soon. overall, i'd like to see far, far more emphasis on how people drive no matter what is in their blood than what is in their blood when they may or may not be having a noticeable problem, i.e. stooping the people who are clearly having a problem driving for whatever reason, be it alcohol, clumsiness, or just being too tired. it is perfectly legal to take over the counter cold remedies and other otc. drugs, many of which can be very impairing to some people. many of the heavy duty cold meds can knock some people right out, as can some allergy products, while others scarcely notice them. benadryl made me drowsy at one time, but i've taken enough of it that it usually actually makes me more awake, because i'm not drowsy from the allergies any more and the benadryl doesn't make me drowsy at all (benadryl is just antihistamine, no decongestants which are generally just stimulants). i had problems with falling asleep driving on the highway (damn alarming!) which i could not figure out, which led to me pulling over while i could and taking short naps (for which some police departments will charge you with drunk driving). some time later i was diagnosed as being diabetic, turns out that probably explains why drinking more cola with caffeine and sugar seemed to make it worse. as i said, i was aware there was a problem, and was diligent about pulling over early on and reduced my driving greatly, but some would not have been as responsible. i also had someone else drive on most of those trips (or left early in the day, and as i said, pulled off at the first sign of drowsiness). sleep deprivation or uncontrolled blood sugar are certainly as dangerous as alcohol, and in some cases no less willful. fortunately my blood sugar is easy to control, now that i know... or it could have been rigged, it's happened before. or they could all just be a bunch of lite weights who haven't drunk in years, though that seems unlikely. William Chops Westfield wrote: {Quote hidden}> > On Jul 4, 2004, at 6:23 PM, Matthew Brush wrote: > > > To the fellow that mentionned Mythbusters, what did > > they try to do to beat the test? I love that show, > > hopefully I'll catch that one soon. Did they get > > hammered? > > I think they did onions, mouthwash, and several other things. None of > them worked; I think one or two (perhaps the mouthwash) sent them > higher. > > Like I said, the interesting part was when they were sitting there > going "ok, I've had 6 drinks in an hour and I'm pretty plastered, lets > go", and the cops kept saying "sorry, you haven't reached the limit > yet. Drink more." (They didn't show the aftermath. I bet it wasn't a > pleasant morning...) > > BillW > > -- > http://www.piclist.com hint: To leave the PICList > EraseMEpiclist-unsubscribe-requestspamspamBeGonemitvma.mit.edu -- <http://www.informationclearinghouse.info/article3267.htm> proof that the U.S. media is now state controlled! Ask your' local tv station why the hell they aren't airing the news any more! Our system of government requires an informed public, with their eyes open. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

that sounds right, but i doubt it's a ratio (meaning that your breathing rate, lung capacity etc. will change it), even if it is, persons with varying metabolisms, on various hear medications (which dilate blood vessels, including those in the lungs and hence increase vapor exchange rates) or decongestants (which constrict blood vessels and would reduce exchange rates) would have an effect, as would several other drugs that effect blood vessels, blood pressure, respiration rate etc. sadly i suspect that in typical use, they are no more reliable than speed guns, which are a joke and should be illegal, but are none the less used as an expediency, justice be dammed. it's very likely that many have been let off who shouldn't have been, or have been charged in error. never mind the problems with police corruption (i'd like to see more police, but i'd also like to see them be a lot more accountable, i like good police, many current police are decidedly bad unfortunately). i also wonder if it's corrected for air temperature and pressure (i live at about 5,000 feet, were water boils around 212 deg F, not 220 as at sea level and there is a lot less oxygen as well, as anyone who drives up from sea level notices rather quickly, or anyone who runs across the yard). there are of course also issues of selectivity, and interfering substances, every chemical sensor i've ever seen has had some flaws in each of those that either didn't matter in the application or were otherwise corrected for. for instance, you don't have to worry about false positives from methanol too much, since they will definitely be having problems from that, though not till the next day (methanol is not poisonous in itself, the body turns it into formaldehyde when it's metabolized, the treatment for exposure is massive ethanol dosing so that most of the enzymes are tied up with that and most of the methanol leaves the body unchanged). you do have to worry about things like some flavorings is suspect, in both directions. "John N. Power" wrote: --------- {Quote hidden}> The theory behind the breath test is that any alcohol in > the mouth itself will evaporate quickly and disappear. I > believe that they ask you to inhale and exhale several > times before taking the test. (I have never been asked to > take the test, but I have read that.) This is to guarantee > that any such residual alcohol will not affect the measurement. > > Alcohol that is swallowed is absorbed into the blood stream > through the stomach wall and is then circulated. This preserves > the alcohol from immediate evaporation. As it passes through > the lungs on each pass, some fraction of the alcohol will > pass back into the air which is exhaled, causing a slow > release of alcohol through the breath. The same phenomenon > occurs after eating certain foods, like onions, which contain > aromatic oils. One's breath will continue to smell like onions > until all of the oils are metabolized. This process takes > a relatively long time and there is nothing that will hurry it up. > > The percent of alcohol in the blood is probably measured by > comparing the concentration of alcohol in the breath sample > with that of some other component in the breath, such as > carbon dioxide. The ratio of the measurements is the actual > indication. This would be similar to measuring pollution > emissions from a car's exhaust by also measuring the CO2 > content and comparing. > > John Power > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- <http://www.informationclearinghouse.info/article3267.htm> proof that the U.S. media is now state controlled! Ask your' local tv station why the hell they aren't airing the news any more! Our system of government requires an informed public, with their eyes open. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Philip Stortz wrote: >yeah, i loved that show, until they were talking about cell phones >blowing up gasoline pumps. now i doubt that cell phones are blowing up >gasoline pumps, but as a demonstration they tried to cause a fuel air >explosion in a Plexiglas box, they couldn't! obviously these guys are >not well versed in the scientific method and don't bother to research >things enough, or they would have know that success would probably have >permanently deafened them, not to mention the property damage. now if >they had tried it with hydrogen or acetylene, they probably would have >managed as both of those have a wide range of explosive mixture with >air, while gasoline apparently has a fairly narrow range (i know some >things have less than a 10% explosive range when mixed with air, and >some will hardly burn if there's a little too much)... > > They did make it explode, several times actually. They never do a "Will it explode..." without actually blowing something up. A few square feet of gasoline/air will not cause excessive damage, nor will hydrogen/air. Pure oxygen would be a different story, as would acetylene/any oxidizer. -- Martin Klingensmith -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email RemoveMElistservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

they eventually got some ignition, but not much. properly done it would have blown out windows nearby. they certainly didn't get much of a pop, and they had to try many times. these are not researcher types or even very familiar with special effects explosions. i new a stunt guy, seems that for the typical semi trailer "explosion" it was common to use less than 8 oz. of gasoline for some time. of course hollywood explosions are usually just fireballs, and many explosives actually produce a minimal fireball, some are even designed not to set off methane in mines. interestingly at the same time hollywood usually makes most explosions too small (way, way too small) for the explosive used or for a missile. the Plexiglas cube built on myth busters would have been fairly dangerous, if they had gotten it right. not that the show isn't amusing sometimes, but it's hardly well researched and the "experiments" are often poorly designed. it took them a long time to get any reaction when they were trying, which makes the earlier "test" with cell phones etc. meaningless, though i do doubt that cell phones cause fires or explosions in the way some people have suggested. Martin Klingensmith wrote: > > Philip Stortz wrote: > ------ {Quote hidden}> > > They did make it explode, several times actually. They never do a "Will > it explode..." without actually blowing something up. A few square feet > of gasoline/air will not cause excessive damage, nor will hydrogen/air. > Pure oxygen would be a different story, as would acetylene/any oxidizer. > -- > Martin Klingensmith > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listservSTOPspamspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body -- <http://www.informationclearinghouse.info/article3267.htm> proof that the U.S. media is now state controlled! Ask your' local tv station why the hell they aren't airing the news any more! Our system of government requires an informed public, with their eyes open. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads