Correlation between oral fluid and blood THC concentration: A systematic review and discussion of policy implications

Cannabis is the second most commonly used impairing substance by drivers, after alcohol. As more countries legalize cannabis, there is concern that cannabis-impaired driving will increase. In many countries, police use roadside devices to test for oral fluid THC (the primary psychotropic component in cannabis) to identify drivers who used cannabis; including in countries with non-zero per se limits for THC in blood. This practice is questioned as previous research demonstrates a poor correlation between oral fluid and blood THC concentrations at the individual level. We conducted a meta-analysis to identify all research that compared oral fluid with blood THC levels. We obtained individual-level data from study authors and analyzed pooled individual-level data to calculate sensitivity and specificity of oral fluid THC (at various cut-off values) to detect blood THC above different concentration limits. Finally, we explored practical implications of using oral fluid THC in an enforcement context. Our review found THC concentrations measured in over 18,000 paired samples of oral fluid and blood. We found a good correlation between the presence of THC in oral fluid and presence of THC in blood (sensitivity = 71.2%, specificity = 97.7%). However oral fluid THC, at commonly used cut-off values, is less sensitive and less specific when used as a biomarker to detect people with blood THC concentrations above commonly used per se limits (such as 5 ng/mL). As such, there will be a large number of "false positive" tests if oral fluid THC testing were used as a biomarker for "illegal" THC concentrations in randomly selected drivers. We argue that the adverse implications of false positive oral fluid THC tests in this context outweigh the possible road safety benefits and we recommend against oral fluid THC screening in randomly selected drivers in countries with non-zero per se limits for blood THC. In contrast, oral fluid THC tests appear to be useful for investigating "high-risk" drivers who come to police attention because of evidence of impairment.

The effect of humidity on germination and infection of termites by the hyphomycete, Metarhizium anisopliae

The effect of relative humidities (r.h.) from 90 to 100% on germination of a termite-active isolate of Metarhizium anisopliae (isolate FI25 and FI610) was studied using a liquid germinating medium to which the appropriate amount of glycerol had been added. Germination was increasingly delayed at water activities equivalent to 99, 98, and 96% r.h. and completely inhibited at 94, 92, and 90%. Twenty-one isolates were then screened for germination at 96 and 100% r.h. All isolates showed delayed germination at 96% r.h. but most isolates eventually gave a high final percentage germination at this humidity. Two isolates, FI527 and FI638, were markedly slower to germinate at both humidities. The susceptibility of two species of termites, Nasutitermes exitiosus and Coptotermes acinaciformis, to FI610 was tested at r.h. down to 86%-the lowest humidity at which the insects would survive. No consistent effect of humidity on pathogenicity was detected. Mortality occurred over the range range of humidities tested; sporulation from the disease-killed termites, however, occurred only at r.h. above 93%. It is concluded that the microclimate around living termites is usually sufficiently humid to ensure infection under most field conditions and that humidity is unlikely to limit the efficacy of the fungus in controlling termites.

T lymphocytes in infectious mononucleosis; effect of IL-2 on the outgrowth of Epstein-Barr virus-infected cells

The addition of interleukin-2 (IL-2) to lymphocyte cultures from acute infectious mononucleosis (IM) donors dramatically increased the incidence of regression in such cultures and resulted in the emergence of an IL-2 dependent, CD3 Epstein-Barr virus nuclear antigen (EBNA)-negative cell population. Corresponding cultures seeded in the absence of IL-2 rarely regressed and were quickly dominated by IL-2 independent, CD3-negative, EBNA-positive cells. Lymphocyte cultures from Epstein-Barr virus (EBV) seropositive donors showed enhanced regression in the presence of IL-2 but failed to regress after the removal of the E-rosetting population. Cultures from EBV-seronegative donors showed no evidence of regression in the presence or absence of IL-2. E-rosetting cells isolated from cultures from acute IM donors that had been cultured in the presence of IL-2 lysed autologous and allogeneic lymphoblastoid cell lines.

Epstein-Barr virus specific T-cell response in nasopharyngeal carcinoma patients

There is a substantial body of evidence suggesting an association between Epstein-Barr virus (EBV) and undifferentiated nasopharyngeal carcinoma (NPC). The present study has compared a group of NPC patients (newly diagnosed and long-term survivors) and controls for EBV-specific T-cell immunity using the regression of transformation assay. Newly diagnosed patients (17 tested) when compared with either long-term survivors (20 tested) or controls (30 tested) showed a significant impairment in virus-specific T-cell immunity (p = 0.036, p = 0.043 respectively). Furthermore, donors with IgA antibody to EBV showed a significant depression in virus-specific T-cell immunity compared with donors without IgA antibody (19 IgA-positive, 48 IgA-negative; p = 0.0025). These results may be important in explaining the postulated role of EBV in the aetiology of NPC.