Rita G. McKeever

Change in perceived risk associated with marijuana use in the United States from 2002 to 2012

Abstract Context. The role of a dynamic legal, medical, and social setting in affecting the perceived risk associated with smoking marijuana has not been well studied. We sought to determine whether there has been a change in the perceived risk associated with marijuana use over time. Methods. A cross-sectional study was conducted using the 2002–2012 National Survey on Drug Use and Health. Respondents were asked to classify the risk of smoking marijuana. Regression analysis and the Mann–Whitney U test were used to analyze the data. Results. A total of 614579 respondents were identified. Between 2002 and 2012, the percent of respondents who characterized regular marijuana use as being associated with “great risk” decreased from 51.3% to 40.3%, while the percent of respondents who characterized it as being associated with “no risk” increased from 5.7% to 11.7%. The percent of respondents who characterized occasional use as “great risk” decreased from 38.2% to 30.7%, while the percent of respondents who characterized it as “no risk” increased from 10% to 16.3%. There was a significant negative temporal trend in the perceived risk for both occasional and regular use of marijuana from 2002 to 2012 after controlling for age and gender (p < 0.001 for both). Increasing age was significantly associated with increased perceived risk for both occasional and regular marijuana use (p < 0.001). Males have a significantly lower perceived risk for regular marijuana use as compared with females (p < 0.001). Individuals who used marijuana during the preceding month reported a lower risk perception in both regular and occasional use. Conclusion. Between 2002 and 2012, there was a significant decrease in the perceived risk associated with occasional and regular marijuana use. Younger age, male gender, and past month use were also associated with decreased perceived risk.

Urine uranium concentrations and renal function in residents of the United States--2001 to 2010.

Context: Animal model studies have demonstrated that subchronic oral uranium exposure is associated with renal dysfunction. Little is known about the effects of environmental exposure to uranium in humans. Objective: To determine whether environmental exposure to uranium is associated with alterations in renal function among residents of the United States. Methods: We analyzed data from the National Health and Nutrition Examination Survey (NHANES) 2001–2010. Inclusion criteria included the measurement of urine uranium concentration, serum creatinine (sCr), and urine albumin-creatinine ratio. Exclusion criteria included a reported history of diabetes mellitus. Urine uranium concentrations were normalized to urinary creatinine. Respondents with and without detectable urine uranium concentrations were compared using Welch’s t-test for urine albumin-creatinine ratio and sCr and using Fisher’s exact test for a reported history of renal disease. Regression analysis was performed to assess for an association between urine uranium concentration and urine albumin-creatinine ratio, sCr, or a reported history of renal disease. Results: Uranium was detectable in the urine of 74.1% (n = 9025) of respondents. Urine albumin-creatinine ratio was significantly greater in respondents with detectable urine uranium concentrations (mean 4.84 ± 45.8 mg/g) compared to respondents without detectable urine uranium concentrations (mean 0.77 ± 3.7 mg/g) (p < 0.001). There was no significant difference between the groups with respect to sCr or a reported history of renal disease. Regression analysis did not show a statistically significant association between urine uranium concentration and urine albumin-creatinine ratio (p = 0.45), sCr (p = 0.71), or a reported history of renal disease (p = 0.05). Conclusions: In this study, a high proportion of the U.S. population had exposure to uranium. We demonstrated an association between detectable urine uranium concentrations and microalbuminuria in residents of the United States but no association with clinical renal disease.

Issues in driving impairment

Motor vehicle crashes (MVC) are an important cause of morbidity and mortality in developed and developing countries, including the United States. While simple human error is an unavoidable cause of MVC, the increased risk of driving errors due to pharmacologic or physiologic impairment is potentially avoidable. The act of driving is a combination of complex tasks and impairment in one or more of those complex tasks results in driving impairment. Numerous causes of driving impairment have been identified. These include alcohol, illicit drugs, licit medications, fatigue, distraction, as well as a variety of medical conditions. We describe the scope of driving impairment as a public health problem, the measurement of driving impairment, and review important causes of impaired driving.

The epidemiology and characteristics of carbon monoxide poisoning among recreational boaters.

Abstract Introduction. Carbon monoxide (CO) poisoning has been reported in the setting of recreational boating however, previous research addressing the epidemiology of carbon monoxide-related injury and death in recreational boaters has been limited. Materials and methods. The United States Coast Guard (USCG) Recreational Boating Statistics annual reports for the 10-year period 2002 – 2011 were analyzed to determine the epidemiology and characteristics of carbon monoxide poisoning among recreational boaters in the United States. Regression analysis was performed to determine statistical significance for trend. Results. The mean number of accidents, injuries and deaths per year due to CO exposure on recreational watercrafts was 14.5 (95% CI 12.1-16.9), 30.9 (95% CI 22.4-39.4) and 6.7 (95% CI 4.5-9.0) respectively. Cabin motorboats accounted for 49 accidents, 123 injuries and 29 deaths. California had 24 carbon monoxide- related accidents over the 10-year study period. Regression analysis showed no overall linear trend in the number of carbon monoxide-related boating accidents, injuries, or deaths as an absolute number or as a percent of all boating accidents, injuries or deaths over the study period. Discussion. The majority of carbon monoxide-related boating accidents, injuries and deaths occurred with cabin motorboats. The state with the largest number of carbon monoxide-related accidents over the 10-year study period was California. Conclusions. Carbon monoxide-related accidents involving recreational boating constitute an important and under recognized cause of injury and death in the United States.

Effect of single-dose Ginkgo biloba and Panax ginseng on driving performance

Abstract Context. Panax ginseng and Gingko biloba are commonly used herbal supplements in the United States that have been reported to increase alertness and cognitive function. Objective. The objective of this study was to investigate the effects of these specific herbals on driving performance. Materials and methods. 30 volunteers were tested using the STISIM3® Driving Simulator (Systems Technology Inc., Hawthorne, CA, USA) in this double-blind, placebo-controlled study. The subjects were randomized into 3 groups of 10 subjects per group. After 10-min of simulated driving, subjects received either ginseng (1200 mg), Gingko (240 mg), or placebo administered orally. The test herbals and placebo were randomized and administered by a research assistant outside of the study to maintain blinding. One hour following administration of the herbals or placebo, the subjects completed an additional 10-min of simulated driving. Standard driving parameters were studied including reaction time, standard deviation of lateral positioning, and divided attention. Data collected for the divided attention parameter included time to response and number of correct responses. The data was analyzed with repeated-measures analysis of variance (ANOVA) and Kruskal-Wallis test using SPSS 22 (IBM, Armonk, NY, USA). Results. There was no difference in reaction time or standard deviation of lateral positioning for both the ginseng and Ginkgo arms. For the divided attention parameter, the response time in the Ginkgo arm decreased from 2.9 to 2.5 s. The ginseng arm also decreased from 3.2 to 2.4 s. None of these values were statistically significant when between group differences were analyzed. Discussion and conclusion. The data suggests there was no statistically significant difference between ginseng, Ginkgo or placebo on driving performance. We postulate this is due to the relatively small numbers in our study. Further study with a larger sample size may be needed in order to elucidate more fully the effects of Ginkgo and ginseng on driving ability.

The American Academy of Clinical Toxicology Question of the Day

Question 1: What is the OSHA “action level” for lead? What is the OSHA requirement for the temporary removal of employees from lead exposure? Answer: The OSHA action level means “employee exposure, without regard to the use of respirators, to an airborne concentration of lead of 30 micrograms per cubic meter of air (30 mg/m3) averaged over an 8-hour period.” OSHA requires the removal of covered employees from lead exposure as follows: “The employer shall remove an employee from work having an exposure to lead at or above the action level on each occasion that a periodic and a follow-up blood sampling test conducted pursuant to this section indicate that the employees blood lead level is at or above 60 micrograms/100 g of whole blood; and, The employer shall remove an employee from work having an exposure to lead at or above the action level on each occasion that the average of the last three blood sampling tests conducted pursuant to this section (or the average of all blood sampling tests conducted over the previous six (6) months, whichever is longer) indicates that the employees blood lead level is at or above 50 micrograms/100 g of whole blood; provided, however, that an employee need not be removed if the last blood sampling test indicates a blood lead level below 40 micrograms/100 g of whole blood.” (http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table1⁄4standards&p_id1⁄410030). Commentary: Adults with occupational lead exposures are at risk for developing lead toxicity. Occupational Safety and Health Administration (OSHA) is responsible for establishing workplace safety regulations regarding chemical exposures. Physicians need to be aware of OSHA’s regulations when providing recommendations for adults with occupational lead exposure and to know when OSHA notification is required. RS.