Determinants of early-stage hearing loss among a cohort of young workers with 16-year follow-up.

OBJECTIVES: The authors had a unique opportunity to study the early impacts of occupational and recreational exposures on the development of noise-induced hearing loss (NIHL) in a cohort of 392 young workers. The objectives of this study were to estimate strength of associations between occupational and recreational exposures and occurrence of early-stage NIHL and to determine the extent to which relationships between specific noise exposures and early-stage NIHL were mitigated through the use of hearing protection. METHODS: Participants were young adults who agreed to participate in a follow-up of a randomised controlled trial. While the follow-up study was designed to observe long-term effects (up to 16 years) of a hearing conservation intervention for high school students, it also provided opportunity to study the potential aetiology of NIHL in this worker cohort. Study data were collected via exposure history questionnaires and clinical audiometric examinations. RESULTS: Over the 16-year study period, the authors documented changes to hearing acuity that exceeded 15 dB at high frequencies in 42.8% of men and 27.7% of women. Analyses of risk factors for NIHL were limited to men, who comprised 68% of the cohort, and showed that risks increased in association with higher levels of the most common recreational and occupational noise sources, as well as chemical exposures with ototoxic potential. Use of hearing protection and other safety measures, although not universal and sometimes modest, appeared to offer some protection. CONCLUSIONS: Early-stage NIHL can be detected in young workers by measuring high-frequency changes in hearing acuity. Hearing conservation programmes should focus on a broader range of exposures, whether in occupational or non-occupational settings. Priority exposures include gunshots, chainsaws, power tools, smoking and potentially some chemical exposures.

Randomized trial of a hearing conservation intervention for rural students: long-term outcomes.

OBJECTIVES: We had the rare opportunity to conduct a cluster-randomized controlled trial to observe the long-term (16-year) effects of a well-designed hearing conservation intervention for rural high school students. This trial assessed whether the intervention resulted in (1) reduced prevalence of noise-induced hearing loss (NIHL) assessed clinically and/or (2) sustained use of hearing protection devices. METHODS: In 1992-1996, 34 rural Wisconsin schools were recruited and 17 were assigned randomly to receive a comprehensive, 3-year, hearing conservation intervention. In 2009-2010, extensive efforts were made to find and contact all students who completed the original trial. Participants in the 16-year follow-up study completed an exposure history questionnaire and a clinical audiometric examination. Rates of NIHL and use of hearing protection were compared. RESULTS: We recruited 392 participants from the original trial, 200 (53%) from the intervention group and 192 (51%) from the control group. Among participants with exposure to agricultural noise, the intervention group reported significantly greater use of hearing protection compared with the control group (25.9% vs 19.6%; P = .015). The intervention group also reported significantly greater use of hearing protection for shooting guns (56.2% vs 41.6%; P = .029), but the groups reported similar uses of protection in other contexts. There was no significant difference between groups with respect to objective measures of NIHL. CONCLUSION: This novel trial provides objective evidence that a comprehensive educational intervention by itself may be of limited effectiveness in preventing NIHL in a young rural population.

Ergonomic risks and musculoskeletal disorders in production agriculture: recommendations for effective research to practice.

Musculoskeletal disorders (MSDs) are increasingly recognized as a significant hazard of agricultural occupation. In agricultural jobs with significant physical labor, MSDs are typically the most frequently reported injury. Although not as lethal as tractor roll-overs, MSDs can result in disability, lost work time, and increased production costs. MSDs increase production costs as a result of worker absence, medical and insurance costs, decreased work capacity, and loss of employees to turnover and competition from other less physically demanding industries. This paper will provide an overview of what is currently known about MSDs in agriculture, including high-risk commodities, tasks and work practices, and the related regulatory factors and workers' compensation costs. As agricultural production practices evolve, the types of MSDs also change, as do ergonomic risk factors. One example is the previous higher rates of knee and hip arthritis identified in farmers in stanchion dairies evolving into upper extremity tendonitis, arthritis, and carpal tunnel syndrome now found in milking technicians in dairy milking parlors. This paper summarizes the presentation, "Musculoskeletal Disorders in Labor-Intensive Operations," at the Agricultural Safety and Health Council of America/National Institute for Occupational Safety and Health conference, "Be Safe, Be Profitable: Protecting Workers in Agriculture," January 27-28, 2010, Dallas/Fort Worth, Texas. The primary focus of the paper is to address current research on ergonomic solutions for MSDs in agriculture. These include improved tools, carts or equipment, as well as work practices. One of the key challenges in this area pertains to measurement, due to the fact that musculoskeletal strain is a chronic condition that can come and go, with self-reported pain as its only indicator. Alternative measurement methods will be discussed. Finally, the implementation of research into practice is reviewed, with an emphasis on best practices that have been demonstrated to be effective in the agricultural setting, based on worker acceptance and comfort, improved productivity, and decreased MSDs. The paper will provide an overview for agricultural stakeholders as to the current science and practice of ergonomics in agriculture.

Hearing conservation program for agricultural students: short-term outcomes from a cluster-randomized trial with planned long-term follow-up.

OBJECTIVES: (1) To conduct a contemporary analysis of historical data on short-term efficacy of a 3-year hearing conservation program conducted from 1992 to 1996 in Wisconsin, USA, with 753 high school students actively involved in farm work; (2) to establish procedures for assessment of hearing loss for use in a recently funded follow-up of this same hearing conservation program cohort. METHODS: We analyzed a pragmatic cluster-randomized controlled trial, with schools as the unit of randomization. Thirty-four rural schools were recruited and randomized to intervention or control. The intervention included classroom instruction, distribution of hearing protection devices, direct mailings, noise level assessments, and yearly audiometric testing. The control group received the audiometric testing. RESULTS: Students exposed to the hearing conservation program reported more frequent use of hearing protection devices, but there was no evidence of reduced levels of noise-induced hearing loss (NIHL). CONCLUSION: Our analysis suggests that, since NIHL is cumulative, a 3-year study was likely not long enough to evaluate the efficacy of this intervention. While improvements in reported use of hearing protection devices were noted, the lasting impact of these behaviors is unknown and the finding merits corroboration by longer term objective hearing tests. A follow-up study of the cohort has recently been started.

Food safety issues: a summary report of a panel session addressing pre- and post-harvest strategies to improve public health.

The paper presents a summary of a panel presentation by animal scientists and public health veterinarians on food safety methods to improve public health of the public consuming beef and poultry. Pre-harvest methods discussed include vaccination to decrease shedding of Esherichia coli O157:H7, direct-fed microbials (DFMs), calving methods, and responsible use of antimicrobials. Post-harvest methods discussed include increased sampling and use of hazard analysis and critical control point (HACCP) methods, test-and-hold of meat products prior to release for public consumption, development of attainment categories, the use of pulsed field gel electrophoresis (PFGE) for genotyping and serotyping, and an 11-step surveillance program. The public health concern and financial consequences of contamination with E. coli O157:H7 is discussed. A "carrot and stick" approach for both producers and processors to increase vaccination and product testing is recommended.

Health effects of airborne exposures from concentrated animal feeding operations.

Toxic gases, vapors, and particles are emitted from concentrated animal feeding operations (CAFOs) into the general environment. These include ammonia, hydrogen sulfide, carbon dioxide, malodorous vapors, and particles contaminated with a wide range of microorganisms. Little is known about the health risks of exposure to these agents for people living in the surrounding areas. Malodor is one of the predominant concerns, and there is evidence that psychophysiologic changes may occur as a result of exposure to malodorous compounds. There is a paucity of data regarding community adverse health effects related to low-level gas and particulate emissions. Most information comes from studies among workers in CAFO installations. Research over the last decades has shown that microbial exposures, especially endotoxin exposure, are related to deleterious respiratory health effects, of which cross-shift lung function decline and accelerated decline over time are the most pronounced effects. Studies in naïve subjects and workers have shown respiratory inflammatory responses related to the microbial load. This working group, which was part of the Conference on Environmental Health Impacts of Concentrated Animal Feeding Operations: Anticipating Hazards-Searching for Solutions, concluded that there is a great need to evaluate health effects from exposures to the toxic gases, vapors, and particles emitted into the general environment by CAFOs. Research should focus not only on nuisance and odors but also on potential health effects from microbial exposures, concentrating on susceptible subgroups, especially asthmatic children and the elderly, since these exposures have been shown to be related to respiratory health effects among workers in CAFOs.