We’ve had this question before. In the previous reply Joel noted the primary reason people ask this question is because they are trying to get around an insurance exam. His advice is always to look at the actual smoking cessation insurance policy requirements to obtain the preferred rate and honestly stay off for that duration of time. Trying to cheat the system is not in any person's best interest.

Almost all insurance policies have a contestability clause. If fraud is discovered to have been committed during the contestability period the insurance company is clearly within its rights to withhold the claim all together. You may pay a fortune in premiums and be eligible to collect nothing at the time of a claim. It isn't worth the financial risk and if you are trying to cheat at quitting smoking, more importantly, it is not worth the health implications and the life threatening aspects of failing to quit that would accompany trying to cheat.

The most important timing lesson from a cessation standpoint is that all nicotine is rapidly excreted or metabolized. Within 3 days of all nicotine cessation no test, regardless of sensitivity, will detect any nicotine remaining in the body. Within 3 days peak physical nicotine withdrawal is complete and you'll gradually begin feeling better. But some of the twenty chemicals nicotine breaks down into remain in the body longer. One of those twenty chemicals is cotinine. Both nicotine and cotinine levels can be established by examining blood, urine or saliva.

"Half-life" is defined as the amount of time required for half the quantity of a drug or other substance deposited in a living organism to be metabolized or eliminated by normal biological processes. While nicotine’s half-life is rather short, an average of about 2 hours (variance 1 to 3), cotinine’s average half-life is about 20 hours (variance 8.8 to 22 hours) and can be detected longer. Both nicotine and continine’s half-life can vary based on such factors as body mass, race, pregnancy status, genetics, alcohol use, stress levels, acidic food intake or vitamin C intake (the last three acid generating factors are capable of accelerating metabolism rates of the alkaloid nicotine).

The most dramatic fluxuation is with pregnancy.  Pregnancy produces numerous changes in body physiology that substantially diminish the half-life of cotinine (progressive blood volume increase by 45-50%, 40% greater cardiac output, liver pH changes) . A May 2002 study of 10 pregnant smokers found an average 8.8 hour cotinine half-life as compared to 16.6 hours after having given birth.

Cotinine concentration in liquid is measured in nanograms per milliliter, represented as ng/ml. A nanogram is one-billionth of a gram and a gram is about 1/40 of an ounce. A milliliter measures fluid volume equal to 1/1000 liter and a liter is a little bigger than a quart.

In blood-serum the cotinine cutoff level used to identify a smoker ranges from 10 to 15 ng/ml.  The cutoff level is approximately ten times higher for urine.  There are a number of commercial products available to measure urine cotinine.  Urine cotinine results of 100 to 200 ng/ml will classify a person as a smoker for both NicAlert and TobacAlert, and 200 ng/ml or above for SureStep.

But exposure to secondhand smoke and low levels of nicotine that occasional smokers generate (chippers) can create controversy surrounding cutoff levels. An April 2001 study found that 7.5% of self reported smokers had blood-serum cotinine levels less than or equal to 15.0 ng/ml. The same study also found that among self-reported nonsmokers, 1.4% had a blood-serum cotinine level greater than 15.0 ng/ml.

The blood cotinine levels of smokers can vary greatly even within what appear to be a group with substantially similar traits. A 2000 study examined cotinine levels in 237 Southeast Asian smokers. The group averaged 11.2 cigarettes per day and had a mean cotinine level of 65 ng/ml. The same study also reports on a second study in which both blood and saliva cotinine in six Southeast Asian adult smokers were measured during 2 days of smoking followed by 6 days of abstinence. On day 1, mean plasma and saliva continine levels were 268 and 235 ng/ml, respectively. After 6 days of abstinence, mean levels had dropped to 12 ng/ml for plasma and 8 ng/ml in saliva. On average, it required at least 4.7 days for saliva cotinine levels to reach less than 14 ng/ml.

Although cotinine levels should be down to non-smoker levels within ten days regardless of the level of prior smoking, like preserved growth rings on a tree not so with hair nicotine testing. There is no half-life metabolism in hair. A 2002 study examined hair cotinine testing to determine the amount of secondhand smoke (ETS) being breathed in by children. According to the study, hair is "less affected by the daily fluctuation of ETS exposure because of the slow growth rate of hair, and it provides a long term exposure history because each 1 cm of hair represents approximately one month's exposure."

Another 2002 study asserts that if the objective is to measure time related exposure to nicotine then it’s important to focus on the exact length of the hair from the scalp but if the aim is to determine the concentration of nicotine exposure per the weight of the hair then hair length is irrelevant. According to the study, "It is believed that nicotine moves by passive diffusion from the bloodstream into the growing hair cells at the base of the follicle and then becomes tightly bound in the interior of the hair shaft during subsequent keratogenesis. Therefore, nicotine incorporation in hair is dependent on the average concentration in blood over time, which in turn depends on the dose inhaled or ingested."

Although it may be possible to identify a smoker far longer by using lengthy hair samples, it has a number of accuracy drawbacks associated with such factors as irregular hair growth rates, hair color, hair type, the affect of strong hair treatments using detergents or permanents, nicotine extraction variances between different labs, a lack of hair in many subjects and cost.

As a seven year recovered nicotine addict myself I’d strongly recommend that any person concerned about nicotine/cotinine testing instead make one complete read of Joel’s free quit smoking book, Never Take Another Puff. It can be read online in HTML format in Joel’s Library ( http://whyquit.com/joel/ ) or downloaded in PDF format at this link (http://whyquit.com/books.html ).

We’re told that ongoing dependency upon smoking nicotine brings with it a 50% of losing 13 to 14 years of life. Imagine residing inside a mind that is so sick that it’s willing to trade one chemical for most of what should be life’s golden years. To both pass these tests and begin turning the risks around is as simple as no nicotine just one day at a time, Never Take Another Puff!

John
Nicotine free since May, 1999
Nicotine Cessation Educator