Cell-surface phosphatidylserine regulates osteoclast precursor fusion.

Bone-resorbing multinucleated osteoclasts that play a central role in the maintenance and repair of our bones are formed from bone marrow myeloid progenitor cells by a complex differentiation process that culminates in fusion of mononuclear osteoclast precursors. In this study, we uncoupled the cell fusion step from both pre-fusion stages of osteoclastogenic differentiation and the post-fusion expansion of the nascent fusion connections. We accumulated ready-to-fuse cells in the presence of the fusion inhibitor lysophosphatidylcholine and then removed the inhibitor to study synchronized cell fusion. We found that osteoclast fusion required the dendrocyte-expressed seven transmembrane protein (DC-STAMP)-dependent non-apoptotic exposure of phosphatidylserine at the surface of fusion-committed cells. Fusion also depended on extracellular annexins, phosphatidylserine-binding proteins, which, along with annexin-binding protein S100A4, regulated fusogenic activity of syncytin 1. Thus, in contrast to fusion processes mediated by a single protein, such as epithelial cell fusion in Caenorhabditis elegans, the cell fusion step in osteoclastogenesis is controlled by phosphatidylserine-regulated activity of several proteins.

The impact of weather, road surface, time-of-day, and light conditions on severity of bicycle-motor vehicle crash injuries.

BACKGROUND: This study examined whether environmental variables including weather, road surface, time-of-day, and light conditions were associated with the severity of injuries resulting from bicycle-motor vehicle crashes. METHODS: Using log-binomial regressions, we analyzed 113 470 police reports collected between 2000 and 2014 in four U.S. states with environmental and injury severity information. "Severe" injuries included fatal and incapacitating injuries, and "non-severe" included non-incapacitating, possible or no-injuries. RESULTS: Light condition was significantly associated with the injury severity to the bicyclist with more severe injuries at dawn (RR = 1.62 [95%CI 1.35-1.94]) and during darkness (both lighted and unlighted roads: 1.32 [1.24-1.40], respectively, 1.57 [1.41-1.76]) as compared to daylight. In these conditions of low visibility, risk was further increased during early morning hours before 7 am (1.61 [1.22-2.13]). CONCLUSIONS: Crashes in low light conditions and during early morning hours are more likely to result in higher injury severity.

Combining statistics from two national complex surveys to estimate injury rates per hour exposed and variance by activity in the USA.

BACKGROUND: A common issue in descriptive injury epidemiology is that in order to calculate injury rates that account for the time spent in an activity, both injury cases and exposure time of specific activities need to be collected. In reality, few national surveys have this capacity. To address this issue, we combined statistics from two different national complex surveys as inputs for the numerator and denominator to estimate injury rate, accounting for the time spent in specific activities and included a procedure to estimate variance using the combined surveys. METHODS: The 2010 National Health Interview Survey (NHIS) was used to quantify injuries, and the 2010 American Time Use Survey (ATUS) was used to quantify time of exposure to specific activities. The injury rate was estimated by dividing the average number of injuries (from NHIS) by average exposure hours (from ATUS), both measured for specific activities. The variance was calculated using the 'delta method', a general method for variance estimation with complex surveys. RESULTS: Among the five types of injuries examined, 'sport and exercise' had the highest rate (12.64 injuries per 100 000 h), followed by 'working around house/yard' (6.14), driving/riding a motor vehicle (2.98), working (1.45) and sleeping/resting/eating/drinking (0.23). The results show a ranking of injury rate by activity quite different from estimates using population as the denominator. CONCLUSIONS: Our approach produces an estimate of injury risk which includes activity exposure time and may more reliably reflect the underlying injury risks, offering an alternative method for injury surveillance and research.

A structural equation modelling approach examining the pathways between safety climate, behaviour performance and workplace slipping.

OBJECTIVE: Safety climate has previously been associated with increasing safe workplace behaviours and decreasing occupational injuries. This study seeks to understand the structural relationship between employees' perceptions of safety climate, performing a safety behaviour (ie, wearing slip-resistant shoes) and risk of slipping in the setting of limited-service restaurants. METHODS: At baseline, we surveyed 349 employees at 30 restaurants for their perceptions of their safety training and management commitment to safety as well as demographic data. Safety performance was identified as wearing slip-resistant shoes, as measured by direct observation by the study team. We then prospectively collected participants' hours worked and number of slips weekly for the next 12 weeks. Using a confirmatory factor analysis, we modelled safety climate as a higher order factor composed of previously identified training and management commitment factors. RESULTS: The 349 study participants experienced 1075 slips during the 12-week follow-up. Confirmatory factor analysis supported modelling safety climate as a higher order factor composed of safety training and management commitment. In a structural equation model, safety climate indirectly affected prospective risk of slipping through safety performance, but no direct relationship between safety climate and slips was evident. CONCLUSIONS: Results suggest that safety climate can reduce workplace slips through performance of a safety behaviour as well as suggesting a potential causal mechanism through which safety climate can reduce workplace injuries. Safety climate can be modelled as a higher order factor composed of safety training and management commitment.

Late stages of the synchronized macrophage fusion in osteoclast formation depend on dynamin.

Macrophage fusion that leads to osteoclast formation is one of the most important examples of cell-cell fusion in development, tissue homoeostasis and immune response. Protein machinery that fuses macrophages remains to be identified. In the present study, we explored the fusion stage of osteoclast formation for RAW macrophage-like murine cells and for macrophages derived from human monocytes. To uncouple fusion from the preceding differentiation processes, we accumulated fusion-committed cells in the presence of LPC (lysophosphatidylcholine) that reversibly blocks membrane merger. After 16 h, we removed LPC and observed cell fusion events that would normally develop within 16 h develop instead within 30-90 min. Thus, whereas osteoclastogenesis, generally, takes several days, our approach allowed us to focus on an hour in which we observe robust fusion between the cells. Complementing syncytium formation assay with a novel membrane merger assay let us study the synchronized fusion events downstream of a local merger between two plasma membranes, but before expansion of nascent membrane connections and complete unification of the cells. We found that the expansion of membrane connections detected as a growth of multinucleated osteoclasts depends on dynamin activity. In contrast, a merger between the plasma membranes of the two cells was not affected by inhibitors of dynamin GTPase. Thus dynamin that was recently found to control late stages of myoblast fusion also controls late stages of macrophage fusion, revealing an intriguing conserved mechanistic motif shared by diverse cell-cell fusion processes.

Work in multiple jobs and the risk of injury in the US working population.

OBJECTIVES: We compared the risk of injury for multiple job holders (MJHs) with that for single job holders (SJHs). METHODS: We used information from the National Health Interview Survey for the years 1997 through 2011 to estimate the rate of multiple job holding in the United States and compared characteristics and rates of self-reported injury (work and nonwork) for SJHs versus MJHs. RESULTS: Approximately 8.4% of those employed reported working more than 1 job in the week before the interview. The rate of work and nonwork injury episodes per 100 employed workers was higher for MJHs than for SJHs (4.2; 95% confidence interval [CI] = 3.5, 4.8; vs 3.3; 95% CI = 3.1, 3.5 work injuries and 9.9; 95% CI = 8.9, 10.9; vs 7.4; 95% CI = 7.1, 7.6 nonwork injuries per 100 workers, respectively). When calculated per 100 full-time equivalents (P < .05), the rate ratio remained higher for MJHs. CONCLUSIONS: Our findings suggest that working in multiple jobs is associated with an increased risk of an injury, both at work and not at work, and should be considered in injury surveillance.

Differences in time use and activity patterns when adding a second job: implications for health and safety in the United States.

OBJECTIVES: We compared work and lifestyle activities for workers who work in 1 job with those who work in multiple jobs during a 1-week period. METHODS: We used information from the 2003-2011 American Time Use Survey to classify workers into 6 work groups based on whether they were a single (SJH) or multiple (MJH) job holder and whether they worked their primary, other, multiple, or no job on the diary day. RESULTS: The MJHs often worked 2 part-time jobs (20%), long weekly hours (27% worked 60+ hours), and on weekends. The MJHs working multiple jobs on the diary day averaged more than 2 additional work hours (2.25 weekday, 2.75 weekend day; P < .05), odd hours (more often between 5 pm and 7 am), with more work travel time (10 minutes weekday, 9 minutes weekend day; P < .05) and less sleep (-45 minutes weekday, -62 minutes weekend day; P < .05) and time for other household (P < .05) and leisure (P < .05) activities than SJHs. CONCLUSIONS: Because of long work hours, long daily commutes, multiple shifts, and less sleep and leisure time, MJHs may be at heightened risk of fatigue and injury.

Duration of slip-resistant shoe usage and the rate of slipping in limited-service restaurants: results from a prospective and crossover study.

Several studies have indicated that slip-resistant shoes may have a positive effect on reducing the risk of slips and falls, a leading cause of injury at work. Few studies, however, have examined how duration of shoe usage affects their slip-resistance properties. This study examined the association between the duration of slip-resistant shoes usage and the self-reported rate of slipping in limited-service restaurant workers. A total of 475 workers from 36 limited-service restaurants in the USA were recruited to participate in a 12-week prospective study of workplace slipping. Of the 475 participants, 83 reported changing to a new pair of shoes at least once during the 12-week follow-up. The results show that slip-resistant shoes worn for less than six months were moderately more effective than those worn for more than six months. Changing to a new pair of shoes among those wearing slip-resistant shoes at baseline was associated with a 55% reduction in the rate of slipping (RR = 0.45, 95% CI = 0.23-0.89). Further research is needed to develop criteria for the replacement of slip-resistant shoes.

Prevalence of Periodontal Disease among Patients Reporting to Tertiary Care Hospital in Ranchi.

Background: Despite a huge number of advancements in the medical field, periodontitis still remains one of the most prevalent oral diseases worldwide. Aim: Thus, the primary aim of our study was to evaluate the prevalence of periodontal diseases in patients reporting to the tertiary healthcare setup in Ranchi. Materials and Methods: Based on inclusion criteria, subjects aged 18-60 years were selected and a per forma was filled by the observer. The prevalence of periodontal disease was measured using the community periodontal index, simplified oral hygiene index, and stage of periodontitis. Results: Descriptive variables were assessed using frequency, percentage, mean, and standard deviations, while the categorical analysis was performed using the Chi-square tests. Conclusion: General awareness about periodontal health and regular dental visits should be given utmost importance among the rural populations of every developing country.

Perception of slipperiness and prospective risk of slipping at work.

OBJECTIVES: Falls are a leading cause of injury at work, and slipping is the predominant cause of falling. Prior research has suggested a modest correlation between objective measures (such as coefficient of friction, COF) and subjective measures of slipperiness (such as worker perceptions) in the workplace. However, the degree of association between subjective measures and the actual risk of slipping at the workplace is unknown. This study examined the association between perception of slipperiness and the risk of slipping. METHODS: 475 workers from 36 limited-service restaurants participated in a 12-week prospective cohort study. At baseline, demographic information was collected, participants rated floor slipperiness in eight areas of the restaurant, and work environment factors, such as COF, were measured. Restaurant-level and area-level mean perceptions of slipperiness were calculated. Participants then reported their slip experience at work on a weekly basis for the next 12 weeks. The associations between perception of slipperiness and the rate of slipping were assessed. RESULTS: Adjusting for age, gender, body mass index, education, primary language, mean COF, use of slip-resistant shoes, and restaurant chain, each 1-point increase in mean restaurant-level perception of slipperiness (4-point scale) was associated with a 2.71 times increase in the rate of slipping (95% CI 1.25 to 5.87). Results were similar for area-level perception within the restaurant (rate ratios (RR) 2.92, 95% CI 2.41 to 3.54). CONCLUSIONS: Perceptions of slipperiness and the subsequent rate of slipping were strongly associated. These findings suggest that safety professionals, risk managers and employers could use aggregated worker perceptions of slipperiness to identify slipping hazards and, potentially, to assess intervention effectiveness.

What circumstances prompt a workplace discussion in medical evaluations for back pain?

PURPOSE: To determine how frequently workplace topics emerge in the interactions between patients and providers in an evaluation for low back pain (LBP) and to determine its association with patient and provider characteristics. METHODS: Adults with work-related LBP (N = 97; 64 % male; median age = 38) completed a demographic questionnaire and a survey of disability risk factors, then agreed to audio-taping of their visits with a participating occupational healthcare provider (n = 14). Utterance-level verbal exchanges were categorized by trained coders using the Roter interaction analysis system. In addition, coders flagged any instance of workplace discussion between patients and providers. RESULTS: Workplace discussions occurred in 51 % of visits, and the most frequent topic was physical job demands. Workplace discussions were more frequent among the oldest and youngest patients and when patients were seen by providers who were more patient-centered and made more efforts to establish patient rapport and engagement. However, patients reporting numerous disability risk factors and workplace concerns in the pre-visit questionnaire were no more likely to discuss workplace topics with their providers (p > 0.05). Only the patient-centered orientations of providers and patients remained statistically significant predictors in multivariate modeling (p < 0.05). CONCLUSIONS: Workplace discussions are facilitated by a patient-centered orientation and by efforts to establish patient engagement and rapport, but workplace discussions are no more frequent among patients with the most significant workplace concerns. Screening questionnaires and other assessment tools may be helpful to foster workplace discussions to overcome possible barriers for returning to work.

Mass loading of size-segregated atmospheric aerosols in the ambient air during fireworks episodes in eastern Central India.

The effects of combustion of the fire crackers on the air quality in eastern Central India were studied for the first time during Diwali festival. This case study analyzes the size distribution and temporal variation of aerosols collected in the rural area of eastern Central India during pre-diwali, Diwali and post-diwali period for the year of 2011. Fifteen aerosol samples were collected during the special case study of Diwali period using Andersen sampler. The mean concentrations of PM10 (respirable particulate matter) were found to be 212.8 ± 4.2, 555.5 ± 20.2 and 284.4 ± 5.8 during pre-diwali, Diwali and post-diwali period, respectively. During Diwali festival PM10 concentration was about 2.6 and 1.9 times higher than pre-diwali and post-diwali period, respectively. PM2.5 (fine) and PM1 (submicron) concentrations during Diwali festival were more than 2 times higher than pre-diwali and post-diwali.

Surgery-First Approach for Dentofacial Deformity: A Systematic Review.

This review is based on the surgery-first approach for dentofacial deformity. This review has critically highlighted various promising aspects and factors associated with dentofacial deformity and can be viewed as valuable research work. In addition, this review highlights a systematic manner of surgery that can reduce the possible duration of treatment. The main findings of the review have established that the appropriate approaches to surgery can be beneficial for patients of any age group. The surgery-first approach is mainly utilized for tissue transfer as well as oral cancer as the first-line treatment. This critical review has successfully evaluated the limitations and advantageous traits of the specific surgery approach that has been outlined in this context. It has established the surgery approach as an effective measurement to reduce the time taken for treatment without compromising the patient's health. In the final phase of this review, the accuracy and appropriateness of this surgery-first approach have been effectively demonstrated.

Factors associated with use of slip-resistant shoes in US limited-service restaurant workers.

OBJECTIVES: Slips and falls are a leading cause of injury at work. Several studies have indicated that slip-resistant shoes can reduce the risk of occupational slips and falls. Few studies, however, have examined the determinants of slip-resistant shoe use. This study examined the individual and workplace factors associated with slip-resistant shoe use. METHODS: 475 workers from 36 limited-service restaurants in the USA participated in a study of workplace slipping. Demographic and job characteristic information about each participant was collected. Restaurant managers provided information on whether slip-resistant shoes were provided and paid for by the employer and whether any guidance was given regarding slip-resistant shoe use when they were not provided. Kitchen floor coefficient of friction was measured. Slip-resistant status of the shoes was determined by noting the presence of a 'slip-resistant' marking on the sole. Poisson regression with robust SE was used to calculate prevalence ratios. RESULTS: 320 participants wore slip-resistant shoes (67%). In the multivariate analysis, the prevalence of slip-resistant shoe use was lowest in 15-19-year age group. Women were more likely to wear slip-resistant shoes (prevalence ratio 1.18, 95% CI 1.07 to 1.31). The prevalence of slip-resistant shoe use was lower when no guidance regarding slip-resistant shoes was given as compared to when they were provided by the employer (prevalence ratio 0.66, 95% CI 0.55 to 0.79). Education level, job tenure and the mean coefficient of friction had no significant effects on the use of slip-resistant shoes. CONCLUSION: Provision of slip-resistant shoes was the strongest predictor of their use. Given their effectiveness and low cost, employers should consider providing slip-resistant shoes at work.

Aerosol size distribution and seasonal variation in an urban area of an industrial city in central India.

To study the size distribution and seasonal variations of atmospheric aerosols, size-segregated aerosol samples were collected from July 2009 to June 2010 using the nine-stage cascade impactor aerosol sampler in Durg City, India. The aerosol particles exhibited bimodal size distribution on mass concentration with a peak at 2.5-4.4 µm size ranges in the coarse mode and 2.1-2.5 µm size ranges in the fine mode. The aerosol mass and size distribution during monsoon were found unimodal distribution with a peak in the coarse mode, while they showed trimodal distributions during winter with all three peaks appearing in the fine mode. The annual mean concentration of PM(10) aerosol was found to be 253.5 ± 99.4 µg/m(3), which is four times higher as compared to the annual guideline of National Ambient Air Quality Standards (NAAQS) of India prescribed by the Central Pollution Control Board (CPCB), India. The highest aerosol mass concentrations were found during winter due to enormous biomass burning, while the lowest concentrations were observed during monsoon due to heavy rainfall. Air quality index values calculated in this study showed that 35% of the days were unhealthy for sensitive people, 35% were unhealthy or very unhealthy, while 3.3% were found as hazardous in Durg City, India.

A Study to Evaluate Il1 And Il6 Gingival Crevicular Fluid Levels in Adolescents and Young Adults During the Early Phase of Orthodontic Tooth Movement.

Background: Evaluating the biomarkers during orthodontic therapy allows us to monitor the effectiveness of the treatment, anticipate the future outcome, and also individualize the treatment according to the response of tissue to different force intensities. The crevicular fluid analysis is a valuable diagnostic method that can be used to examine noninvasive cellular metabolic activity. The goal of this study was to compare the levels of interleukin (IL)-1 and IL-6 in the gingival crevicular fluid (GCF) of clinically healthy adolescents and young adults throughout orthodontic treatment. Methods: GCF was obtained from 20 orthodontic patients ranging in age from 11 to 28 years old. Measurements were done before (T0) and after (T24) the activation of distalization forces (T1). Enzyme-linked immunosorbent assay (ELISA) testing was used to look at IL-1 and IL-6. Two-sided t-tests were utilized as statistical testing. Results: The crevicular fluid rate (0.57 L at T0 vs. 0.95 L at T1, P = 0.001) and IL-1 levels (15.67 pg/L at T0 vs. 27.94 pg/L at T1, P = 0.009) both increased significantly between the two time periods. Only a third of the sites tested positive for IL-6. At T1, adolescents have a considerably higher amount of IL than young adults (42.96 pg/L vs. 17.93 pg/L, P = 0.006). Conclusion: Adolescent periodontal tissues are more susceptible to orthodontic forces than young adult periodontal tissues in the early stages of orthodontic treatment.

Oral Hygiene Practices and the Awareness of Perio-Systemic Interrelationship Among the Population of Ranchi City: A Hospital-Based Study.

BACKGROUND: The concept of the pathogenesis and etiology of periodontal disease, with their infectious and chronic natures, usually facilitates acknowledging the possibility of these infections influencing events elsewhere in the body. Concurrent awareness and recognition of the interaction between systemic and oral diseases are one of the enormous advances that require a periodontist to not only strictly direct their knowledge toward prevention and treatment but also spread awareness about the same among the unknown. Thus, the primary goal of our study was to assess public awareness of periodontal and systemic interrelationships with oral hygiene practices in Ranchi, Jharkhand. METHODOLOGY:  A total of 800 subjects between ages 18 and 60 years visiting the outpatient department of periodontology, Dental Institute, Rajendra Institute of Medical Sciences (RIMS), were randomly selected for inclusion in the study. After the oral hygiene checkup, the patients were presented with a self-constructed questionnaire form, where patients' awareness and knowledge about perio-systemic interrelationship and their patterns about oral hygiene practices were assessed. RESULTS: The data collected was analyzed using mean and standard deviation (SD), while the chi-square (χ2) test was to evaluate the mean difference. The results of our study showed a fair oral hygiene index, minimal oral hygiene practices, and a lack of awareness regarding the interrelationship between bad oral health and systemic diseases among the population of Ranchi. Out of 800 subjects, the majority (around 44.25%) visited a dentist only if and when needed, and around 80% of the population continued using their toothbrushes for more than six months. In fact, awareness regarding the perio-systemic interrelationship was only among 5.12% (3.25% ± 1.87%) of the total population. CONCLUSION: Within the limitations of our study, it can be concluded that there is a need to educate the general population about the pros and cons of maintaining oral hygiene. Dental awareness, along with periodontal health care and its impact on systemic health, should be intensified through various means.

Statin Use and Severe Acute Liver Injury Among Patients with Elevated Alanine Aminotransferase.

Introduction: While serious liver injury among statin users is extremely rare, baseline liver enzyme testing is still recommended prior to initiating therapy. The benefit of such screening should be reevaluated based on empirical evidence. This study compared the risk of severe acute liver injury (SALI) between statin initiators with an elevated ALT (>35U/L) matched to statin initiators with a normal ALT level (≤35U/L). Statin initiators with an elevated ALT were additionally compared against matched non-users. Methods: The study created cohorts from Optum and MarketScan claims data. Exposed and comparison cohorts were propensity score (PS) matched in each dataset and findings were pooled using meta-analysis. Proportional hazards regression was used to estimate hazard ratios (HRs), and a prespecified non-inferiority margin for SALI was set at a HR of 1.8. Results: 232,889 patients with elevated ALT were PS-matched to 232,889 with normal ALT level. The overall incidence rate of SALI was about 19/100,000 person-years among statin initiators. Statin initiators with elevated ALT had no meaningfully increased risk of SALI compared to those with normal ALT (HR=1.15; 95% CI 0.75 to 1.75). Comparing statin initiators with non-initiators with elevated ALT values equally yielded no increased risk (HR=0.76; 95% CI 0.52 to 1.11). Conclusion: In this large population-based study, SALI in statin users was rare. Importantly, the results showed no evidence that baseline ALT status is a reliable indicator for an increased risk of severe liver injury among statin initiators.

A prospective study of floor surface, shoes, floor cleaning and slipping in US limited-service restaurant workers.

OBJECTIVES: Slips and falls are a leading cause of injury at work. Few studies, however, have systematically examined risk factors of slipping outside the laboratory environment. This study examined the association between floor surface characteristics, slip-resistant shoes, floor cleaning frequency and the risk of slipping in limited-service restaurant workers. METHODS: 475 workers from 36 limited-service restaurants from three major chains in six states in the USA were recruited to participate in a prospective cohort study of workplace slipping. Kitchen floor surface roughness and coefficient of friction (COF) were measured in eight working areas and then averaged within each restaurant. The use of slip-resistant shoes was determined by examining the participant's shoes and noting the presence of a 'slip-resistant' marking on the sole. Restaurant managers reported the frequency of daily kitchen floor cleaning. Participants reported their slip experience and work hours weekly for up to 12 weeks. The survey materials were made available in three languages: English, Spanish and Portuguese. The associations between rate of slipping and risk factors were assessed using a multivariable negative binomial generalised estimating equation model. RESULTS: The mean of individual slipping rate varied among the restaurants from 0.02 to 2.49 slips per 40 work hours. After adjusting for age, gender, BMI, education, primary language, job tenure and restaurant chain, the use of slip-resistant shoes was associated with a 54% reduction in the reported rate of slipping (95% CI 37% to 64%), and the rate of slipping decreased by 21% (95% CI 5% to 34%) for each 0.1 increase in the mean kitchen COF. Increasing floor cleaning frequency was significantly associated with a decreasing rate of slipping when considered in isolation but not after statistical adjustment for other factors. CONCLUSION: These results provide support for the use of slip-resistant shoes and measures to increase COF as preventive interventions to reduce slips, falls and injuries.

Rushing, distraction, walking on contaminated floors and risk of slipping in limited-service restaurants: a case--crossover study.

OBJECTIVES: This nested case-crossover study examined the association between rushing, distraction and walking on a contaminated floor and the rate of slipping, and whether the effects varied according to weekly hours worked, job tenure and use of slip-resistant shoes. METHODS: At baseline, workers from 30 limited-service restaurants in the USA reported average work hours, average weekly duration of exposure to each transient risk factor and job tenure at the current location. Use of slip-resistant shoes was determined. During the following 12 weeks, participants reported weekly their slip experience and exposures to the three transient exposures at the time of slipping. The case-crossover design was used to estimate the rate ratios using the Mantel-Haenszel estimator for person-time data. RESULTS: Among 396 participants providing baseline information, 210 reported one or more slips with a total of 989 slips. Rate of slipping was 2.9 times higher when rushing as compared to working at a normal pace (95% CI 2.5 to 3.3). Rate of slipping was also significantly increased by distraction (rate ratio (RR) 1.7, 95% CI 1.5 to 2.0) and walking on a contaminated floor (RR 14.6, 95% CI 12.6 to 17.0). Use of slip-resistant shoes decreased the effects of rushing and walking on a contaminated floor. Rate ratios for all three transient factors decreased monotonically as job tenure increased. CONCLUSION: The results suggest the importance of these transient risk factors, particularly floor contamination, on rate of slipping in limited-service restaurant workers. Stable characteristics, such as slip-resistant shoes, reduced the effects of transient exposures.