Passive exposure

Environmental—recent exposures (such as close contact with meningitis or respiratory tract infection, contaminated foods), active or passive exposure to cigarette smoke, close living conditions... 

Samet, J. M., Relationship between passive exposure to cigarette smoke and cancer, in Indoor Air and Human Health, (R. B. Gammage and S. V. Kaye, eds) pp. 227-240 (1985). 

Fresh ambient particulate POM sampled near a freeway was also exposed in this passive system for 3 h in the dark to 200 ppb of 03 in air at 1% RH. Concentrations of specific PAHs determined in the ambient particles and their percent reacted were similar for samples collected on both kinds of filters (glass fiber and TIGF). Again, under passive exposure conditions to approximately ambient levels of 03, BaP and BaA were found to be significantly more reactive than BeP. 

The most frequently cited low probability event, that became apparent as a defense argument for urinalysis, was passive exposure to marijuana smoke. An explanation for a marijuana positive urinalysis was that the service member was exposed to significant quantities of marijuana sidestream smoke in close proximity to the service member. Because this defense may have had validity, the Navy commissioned subsequent scientific studies to resolve this issue. These studies showed conclusively that environmental exposure would result in a marijuana positive, providing the exposure was severe enough. However, in the experiment the exposure needed to be repeated for many hours and at a level such that the subjects needed to wear eye goggles to protect themselves from the marijuana smoke. Exposures at these levels could hardly be considered to be inadvertent or unwilling. As a result of these studies, cutoff levels could be defended and the credibUity of the passive exposure defense was diminished. 

B. Historical Concerns for Passive Exposure in Hair Analysis... 

The phenomena of passive exposure is familiar to most nonsmoking individuals. Like many analytical instruments, the nose is an exquisite detector for some compounds, tobacco smoke being one. After exposure to tobacco smoke in a smoke-filled room and upon returning to his/her spouse that evening, the spouse may readily be able to tell that he/she had been in the presence of a smoker due to smoke clinging to the hair or clothing. 

F. Can Passive Exposure be a Vector for Incorporation of Drugs into Hair ... 

Yes. In situations where drugs are known to be present in the environment, it is easy to demonstrate that passive exposure can produce positive hair analysis results. In a study by Haley and Hoffmaim of the nicotine and cotinine concentrations in the hair of smokers and nonsmokers, there appeared to be a higher average of nicotine in the unwashed hair of smokers (average 8.75 ng/mg). However, nonsmokers also had an appreciable level of nicotine (average 2.42 ng/mg) which overlapped that of smokers. In contrast, cotinine (the nicotine metabolite) does appear to be a marker of tobacco use in this population. More recently, Kintz and co-workers and Kintz proposed a cutoff level of 2 ng of nicotine/mg of hair to ehminate nonsmoking individuals. Even at this level, some nonsmokers would be positive. 

Not all positive hair analysis results are due to passive exposure. Certainly, many positive results are due to ingestion of drugs. This section clearly illustrates that interpretation of the data must take passive exposure into consideration to determine the source of drugs in any given positive result. 

Knudson, M., Non-users test positive, fuel drug screening furor, Baltimore Sun, Nov. 11,1986, p. 2F. Cone, E. J. and Johnson, R. E., Contact highs and urinary cannabinoid excretion after passive exposure to marijuana smoke, Clin. Pharmacol. Ther., 40, 247,1986. 

Blank, D. L. and Kidwell, D. A., Screening of hair for drugs of abuse — is passive exposure a complication, 41st Annual Meeting of the American Academy of Forensic Sciences, Las Vegas, NV, February 1989. 

Zieske, L. A., Passive exposure of cocaine in medical personnel and its relationship to drug screening tests. Arch. Otolaryngol. Head Neck Surg., 118, 364, 1992. 

Goulle, J. R, Noyon, J., and Leroux, R, Nicotine in hair and passive exposure in pediatric pathology, presented at the 16th Congress of the Int. Academy of Legal Medicine and Social Medicine, Strasbourg, May 31 to June 2,1994. 

We have developed special procedures for the avoidance of false positive results and for the accurate interpretation of positive results in terms of drug use, passive exposure to drugs or specimen contamination. This experience with workplace testing will be described along with an assessment of the efficacy and reliability of hair analysis. 

These considerations show clearly that endogenous interpretive false positives are the main problem confronting urinalysis. It is, however, a problem with which hair analysis can provide considerable assistance, since passive exposure as a cause for a positive urinalysis result can be excluded by a positive hair analysis result. As indicated previously, this support is particularly critical in the case of opiates, where considerations of public safety demand that the numerous overturned urinalysis results be further investigated. 

Even though the majority of results were below the adult endogenous cutoff level (not to mention the tenfold higher cutoff level for children) and in spite of the presence of benzoylecgonine which indicated passive exposure. Smith and KidwelPi drew the erroneous conclusion that our wash kinetic criteria failed to... 

V. Hair Nicotine as a Marker of Passive Exposure to Tobacco.271... 

Noninvasive validation of tobacco smoking behavior is necessary for large population health studies. Moreover, a main problem in the risk assessment of passive smoking is the lack of a suitable methodology for the quantification of exposure. Measurements of nicotine in hair could prove to be a reliable marker for passive exposure. Several reports have presented data on nicotine in hair. ° Some have included the monitoring of cotinine, the major metabolite of nicotine. 

All the authors concluded that measurement of nicotine in hair can prove to be a reliable marker for passive exposure. Nicotine is specific to environmental tobacco smoke, and hair nicotine gives retrospectively a time-weighted average measurement of exposure for months. 

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