An amount of 30.5 g of the Mueller-Hintonagar, dehydrated culture media was dissolved in 1L of deionized water and then heated to dissolve completely. Disk diffusion tests were conducted to determine bacterial sensitivity towards AgNPs . The Luria agar was sterilized in the autoclave at 120˚C for 15 minutes. After cooling to around 45˚C, the broth was dispensed into sterile Petri dishes. A 3-way swab plate was prepared on an agarplate and filter disks were placed at intervals on the surface of plates using sterile forceps. The plates were incubated at 37˚C for 24 hours. 10 μlaliquots of 1 mM and 5 mM AgNPs were impregnated on filter disk having uniform bacterial suspensions of E. coli and S. aureus. The diameter of the zone of inhibitionwas measured using photographic images of the agar plates .Using the broth dilution method, the Minimum Inhibitory Concentration of AgNPs was determined and the bactericidal effect of AgNPs was evaluated based on the Minimum Bactericidal Concentration .
The MIC was defined as the lowest concentration of AgNPs, which inhibited bacterial growth.The MBC value was defined as the lowest concentration of nanoparticles that prevented the visible growth of bacteria on the agar plates after incubation. A volume of 0.2 mL of each bacterial strain was added to the test tube containing 1ml broth and was mixed with a serial dilution of 1 mMAgNPs. Positive controls contained 1 mL of Luria broth and 0.2 mL of E. coli and S. aureus strain without containing AgNPs. The negative control contained only Luria broth. Tubes were incubated at 37˚C for 24 hours. Each sample was examined for bacterial growth by monitoring the changes in the visual turbidity with the naked eye. The tubes that appeared to have no or little growth were plated on Luria broth agar plates to differentiate between bactericidal and/or bacteriostatic effect and these plates were incubated at 37˚C for another 24 hours. Marijuana is about to become legal in Canada. Consequently, an analysis of its effects on users is a high priority. Canadian researchers have explored this issue to some extent but there are gaps in what is known about the effects of using marijuana. Most of the Canadian studies, whose results are summarized in Section 3, focus on youth or adolescent use. This is clearly important as is adult use.
The link between early usage and its effect over an individual’s lifetime also needs to be examined. One of the most surprising results that we found is that almost all users start when they are teenagers2. This means that the age group under 21 is the one that should be the center of our attention.It also means that we will not be able to examine the effects of marijuana use on late starters, an issue of considerable interest since it is likely that some Canadian adults will start smoking marijuana because it is no longer illegal and is likely to be more socially acceptable.That using marijuana is a health hazard is not an issue in dispute. The health literature on marijuana use surveyed below finds that using marijuana as an adolescent has a negative impact on both physical and mental health. Longitudinal studies show that individuals who start around the age of 15 and continue to be regular and significant usersin to early adulthood suffer memory loss, cognitive function impairment, diminished IQ, and lower educational success rates. Early users also suffer physically in terms of higher rates of respiratory diseases and higher rates of certain cancers.
What these studies do not show is the duration of these effects. Do they become less debilitating as individuals age or are they of a more permanent nature? Our results show that the damage is permanent. The costs of starting to use marijuana at the age of 15 are borne by the individual for his or her whole lifetime. What is more disturbing is that this result was obtained without any information on actual usage at age of first use.What teenagers use on average when they start to use marijuana imposes health costs on them for the rest of their lives.The paper has the following format. The next section reviews the literature on the health implications of using marijuana. Section 3 discusses the variables, which can be used to measure the effects of marijuana use as well the data employed in our analysis.Section 4 outlines the statistical procedures employed. Section 5 contains our results and they are discussed in Section 5.
The long-term effect of cannabis use is an important medical policy issue, yet there is much uncertainty about it. This is partly due to the limited number of longitudinal studies which have examined marijuana use over extended periods of time and the limitations of sample surveys, which so far have not been able to accurately determine the adverse health effects of regular or early use of marijuana. This is worrying since Rottermanet al.estimated that 43% of Canadians, who are 15 years of age or older used marijuana at least once in their lifetime. As attitudes towards marijuana use become more tolerant and use increases, a better understanding of its effects becomes even more important.