Mark R. Schulz

Occupational exposure assessment in case-control studies: opportunities for improvement

Community based case–control studies are an efficient means to study disease aetiologies, and may be the only practical means to investigate rare diseases. However, exposure assessment remains problematic. We review the literature on the validity and reliability of common case–control exposure assessment methods: occupational histories, job–exposure matrices (JEMs), self reported exposures, and expert assessments. Given the variable quality of current exposure assessment techniques, we suggest methods to improve assessments, including the incorporation of hygiene measurements: using data from administrative exposure databases; using results of studies identifying determinants of exposure to develop questionnaires; and where reasonable given latency and biological half life considerations, directly measuring exposures of study subjects.

A Prospective Cohort Study of Injury Incidence and Risk Factors in North Carolina High School Competitive Cheerleaders

Background Cheerleaders suffer nearly half of catastrophic injuries observed in female scholastic athletes in the United States. However, incidence of noncatastrophic injury in this population has not been described. Hypothesis Coach, athlete, and injury circumstance variables may predict the injury rate among cheerleaders. Study Design Prospective cohort. Methods The authors investigated injury incidence in a sample of North Carolina female cheerleaders who competed interscholastically from 1996 to 1999. Injury, exposure, and demographic data were collected from squads that participated in the North Carolina High School Athletic Injury Study. Results Cheerleaders suffered 133 injuries during 1701 athlete seasons. More than 21% of the injuries were ankle sprains. The injury rate was 8.7; the 95% confidence interval (CI) was 6.5 to 11.7 per 10,000 athlete exposures. In a multivariate Poisson regression model, cheerleaders supervised by coaches with the most education, qualifications, and training (coach EQT) had a nearly 50% reduction in injury risk (rate ratio [RR], 0.5; 95% CI, 0.3-0.9), and cheerleaders supervised by coaches with medium coach EQT had a nearly 40% reduction in injury risk (RR = 0.6; 95% CI, 0.3-1.2) compared to cheerleaders supervised by coaches with low coach EQT.

The prevalence of melasma and its association with quality of life in adult male Latino migrant workers

Background  Melasma is a common condition of Latino women that detracts from their quality of life (QOL). The prevalence and impact of melasma in Latino men is not well characterized.

The prevalence of carpal tunnel syndrome in Latino poultry-processing workers and other Latino manual workers.

Objective: To determine the prevalence of carpal tunnel syndrome (CTS) in Latino poultry-processing workers. Methods: Symptoms and nerve conduction studies were used to prospectively assess 287 Latino poultry-processing workers and 226 Latinos in other manual-labor occupations. Results: The prevalence of CTS was higher in poultry-processing (8.7%) compared with nonpoultry manual workers (4.0%; P < 0.0001). The adjusted odds ratio for the prevalence of CTS in poultry workers was 2.51 (95% confidence interval, 1.80–3.50) compared with nonpoultry workers. Within the poultry workers, those who performed packing, sanitation, and chilling had a trend toward less CTS than those who performed tasks requiring more repetitive and strenuous hand movements. Discussion: Latino poultry-processing workers have a high prevalence of CTS, which likely results from the repetitive and strenuous nature of the work.

Green tobacco sickness and skin integrity among migrant Latino farmworkers.

BACKGROUND Green tobacco sickness (GTS) affects approximately one-quarter of tobacco workers. The primary aim of this analysis is to expand existing knowledge of GTS risk factors by delineating the association of measures of skin integrity with the prevalence of GTS among Latino farmworkers. METHODS Data are from a longitudinal study of skin disease among 304 North Carolina Latino farmworkers conducted in 2005. RESULTS 18.4% of the farmworkers met the GTS case definition. Self-reported rash increased the odds of having GTS in the bivariate (OR 2.29, 95% CI 1.21, 4.35), and multivariate analyses (OR 3.30, CI 2.17, 5.02). Self-reported itch (OR 3.54, CI 2.38, 5.24) and superficial wounds (OR 2.49, CI 1.15, 5.39) had a significant relationship to GTS in the bivariate analysis. CONCLUSIONS These analyses extend current knowledge of GTS risk factors to include skin integrity. Farmworkers with rash and other skin conditions can protect these affected skin areas from exposure to the tobacco plant to reduce their risk of GTS.

Health Care Utilization Among Migrant Latino Farmworkers: The Case of Skin Disease

CONTEXT Skin diseases are common occupational illnesses for migrant farmworkers. Farmworkers face many barriers in accessing health care resources. PURPOSE Framed by the Health Behavior Model, the purpose of this study was to assess health care utilization for skin disease by migrant Latino farmworkers. METHODS Three hundred and four migrant and seasonal Latino farmworkers in North Carolina were enrolled in a longitudinal study of skin disease and health care utilization over a single agricultural season. Self-reported and dermatologist-diagnosed skin condition data were collected at baseline and at up to 4 follow-up assessments. Medical visit rates were compared to national norms. FINDINGS Self-reported skin problems and diagnosed skin disease were common among farmworkers. However, only 34 health care visits were reported across the entire agricultural season, and none of the visits were for skin diseases. Nevertheless, self-treatment for skin conditions was common, including use of non-prescription preparations (63%), prescription products (9%), and home remedies (6%). General medical office visits were reported in 3.2% of the assessments, corresponding to 1.6 office visits per person year. CONCLUSIONS The migrant farmworker population consists largely of young men who make little use of clinic services. Skin conditions are very common among these workers, but use of medical services for these conditions is not common. Instead, farmworkers rely primarily on self-treatment. Clinic-based studies of farmworker skin conditions will not account for most injury or disease in this population and have the potential for biased estimates.

Skin Disease Among Latino Farmworkers in North Carolina

An estimated 4.2 million seasonal and migrant farmworkers and their dependents live in the U.S. Most of these farmworkers are Latino. These workers are exposed to numerous occupational and environmental risk factors that can result in skin disease. Few data exist on the prevalence of skin disease in this population. The purpose of this study was to estimate the prevalence and predictors of skin disease in a sample of Latino farmworkers in North Carolina. A sample of 59 farmworkers was recruited and interviewed at two camps during the 2004 agricultural season. A dermatologist completed a skin exam of each worker and recorded any skin disease present. Forty-two (77.7%) of the 54 men, and all five of the women examined had a diagnosed skin disease. For the men, onychomycosis (nail fungus, 31.5%), tinea pedis (foot fungus, 27.8%), and acne (24.1 %) were the most commonly diagnosed skin diseases, with contact dermatitis diagnosed in 5.6% of the sample. Other diagnoses included scars, sunburn, and atopic dermatitis. Among the women, diagnoses included melasma (dark patches on the face, 2 cases), xerosis (excessively dry skin, 1 case), tinea pedis (2 cases), onychomycosis (1 case), acne (1 case), and insect bites (1 case). There were no statistically significant differences between workers in the two camps despite different growing seasons and different crops harvested. Skin disease is prevalent among the North Carolina Latino farmworkers who participated in this study, with fungal disease being the most prevalent.

Dose-response relation between acrylamide and pancreatic cancer

In their 1999 study of workers exposed to acrylamide, Marsh et al conducted an SMR analysis, and fitted several relative risk regression models to the data.1 In each analysis, they found risk of pancreatic cancer increased by about twofold for workers in the highest cumulative exposure group, but risk of pancreatic cancer did not increase monotonically with cumulative exposure in any of their analyses. Duration of …

Lower Body Stiffness and Muscle Activity Differences Between Female Dancers and Basketball Players During Drop Jumps

Background: Anterior cruciate ligament (ACL) injuries often occur during landing, with female athletes at higher injury risk than male athletes. Interestingly, female dancers have lower ACL injury rates than do female athletes in general. Hypothesis: Female dancers will have earlier and greater lower extremity muscle activity and higher sagittal knee joint and leg stiffness than will female basketball players. Study Design: Cross-sectional group comparison. Methods: Fifty-five healthy female athletes (35 dancers, 20 basketball players) performed 5 double-leg drop jumps from a 45-cm box. Surface electromyography (onsets and amplitudes; prelanding and postlanding) was recorded from the lateral gastrocnemius, medial and lateral hamstrings, lateral quadriceps muscles with a 3-dimensional electromagnetic tracking system, and forceplates recording biomechanics (leg spring stiffness and knee joint stiffness). Results: Compared with basketball players, dancers had greater leg spring stiffness (P = 0.047) but similar knee joint stiffness (P = 0.44). Although no significant differences were observed in overall muscle onset times (P = 0.22) or activation amplitudes (prelanding, P = 0.60; postlanding, P = 0.78), small to moderate effect sizes (ESs) suggest trends in dancers toward earlier (ES = 0.53) and higher medial hamstrings activation pre- (ES = 0.55) and post- (ES = 0.41) landing and lower lateral quadriceps (ES = 0.30) and higher gastrocnemius (ES = 0.33) postlanding muscle activation. Conclusions: In dancers, the higher leg spring stiffness and trends toward higher hamstrings prelanding and postlanding, as well as lower quadriceps and higher gastrocnemius activation postlanding with similar knee joint stiffness, indicate lower extremity neuromechanical differences across other joints. Clinical Relevance: Female dancers may have lower extremity neuromechanics that are different from those of basketball players during drop jumps. If dancers use ACL-protective strategies during activity, then their training routines should be further investigated to improve ACL injury prevention programs.

Diagnosed skin diseases among migrant farmworkers in North Carolina: prevalence and risk factors.

Skin diseases are common among farmworkers, yet little research documents their prevalence and risk factors. This analysis documents the prevalence of skin diseases among farmworkers in North Carolina, examines variation in the prevalence across the agricultural season, and delineates factors associated with skin disease. Data are from a longitudinal surveillance study with assessments at approximately three-week intervals from May through October 2005. The sample included 304 farmworkers from 45 camps with 1048 data points. Data collection included a structured interview and a standard set often digital photographs. A board-certified dermatologist reviewed the photographs and made specific diagnoses in five categories: inflammatory disease, infection, pigmentary disorder, tumor, and trauma. The prevalences of the five skin disease categories and specific diagnoses are described with counts and frequencies for the entire season and for six time periods. The inflammatory disease and infectious disease categories are modeled with an extension of logistic regression that accounts for repeated measures and clustering of farmworkers within camps. Farmworkers experience high levels of inflammatory skin disease (57.2%) including acne, folliculitis, and contact dermatitis; infectious skin disease (73.8%) including tinea pedis, onychomycosis, and warts; pigmentary disorders (19.1%); and trauma (34.5%). The odds of inflammatory skin disease decreased with age, while those for infectious skin disease increased with age. The odds of inflammatory skin disease increased with pesticide exposure and decreasing housing quality. Skin diseases are highly prevalent among farmworkers. Research is needed to delineate specific factors causing high levels of infection and inflammation in this population.