1955: The Entre` of Medicine and Public Health into the Field of Agricultural Occupational Safety and Health

The University of Iowa Institute of Agricultural Medicine (IAM) played a significant role in the development of the field of agricultural medicine. This article is an excerpt from the electronic book The Institute of Agricultural Medicine: an Iowa Idea - Worldwide Impact, 2021(https://pressbooks.uiowa.edu/agriculturalmedicinehistory/) which provides a detailed history of this story.Olaus Magnus (a clergyman in the Christian Church) in Sweden in 1555, and Bernardon Ramazzini (a physician) in Italy in 1713 wrote of health conditions in farmers. However, there is no evidence found (in the Western Hemisphere) before 1955, that a specific institute was present for the preventive health and medicine for farmers, their families, and their workers. There was an e absence of research and outreach in the medical and public health fields in agricultural medicine. The history of the Institute of Agricultural Medicine (IAM) provides a substantive grounding for the field as it stands today. Further, the institute serves as something of a precursor of the One Health Initiative. Here we trace the history of the institute and highlight its contributions to today's field of agricultural medicine.

Health Indicators of a Cohort of Midwest Farmers: Health Outcomes of Participants in the Certified Safe Farm Program

Occupational illness, injury, and fatality rates for those working in production agriculture are higher than in any other industry. A potential risk factor contributing to occupational injuries across all industries is acute or chronic co-morbidity (e.g., obesity, high blood pressure, high cholesterol), and related health issues that increase the risk for an occupational injury or illness. These chronic health conditions have been associated not only with increased risk for injuries, but also higher health-care costs, and greater absenteeism. Certified Safe Farm (CSF) is a comprehensive intervention program aimed to reduce occupational health and safety hazards and to promote general health among farmers. Prior publications have described CSF program efforts to reduce hazardous exposures, disabling injuries, organic dust toxic syndrome, occupational health-care costs, and to increase positive occupational health behaviors. This paper reports on the general health indicators of a cohort of 438 Iowa farm owner/operators enrolled in the CSF program. Overall, this study found that the farming population in Iowa has higher body mass index (BMI), but lower total cholesterol, low-density lipoprotein (LDL), and lower prevalence of hypertension compared to the general population. There was evidence that the combination of high blood pressure, cholesterol, and BMI were related to increased injury rates. Poor self-reported health status was also related to increased injuries but was not related to clinical health indicators. The CSF intervention led to improvements on health outcomes, particularly among those in the 35 to 49 age group. Little research has focused on the individual's general health status as a predictor of risk of occupational injury. This study suggests the need for additional research and interventions integrating occupational safety and health prevention along with health promotion.

Translating agricultural health and medicine education across the Pacific: a United States and Australian comparison study

BACKGROUND

Populations in agricultural communities require<b> </b>health care that is interdisciplinary and cross-sectoral to address the high rate of workplace deaths, preventable injuries and illness. These rates are compounded by limited access to services and the distinctive personal values and culture of farming populations, which both health and rural practitioners must be aware of to reduce the gap between rural and urban population health outcomes. To address the unique health and medical characteristics of agricultural populations, education in agricultural medicine was established through the College of Medicine and the College of Public Health at the University of Iowa in the USA. The course was initially developed in 1974 for teaching medical students, family medicine residents and nurses, and a postgraduate curriculum was added in 2006 to develop medical/health and rural professionals' cultural competence to work in agricultural communities. This article reviews the adaptation of the US course to Australia and the educational and practice outcomes of students who completed the agricultural medicine course in either Australia or the USA.

METHODS

Data were collected from students who completed either the Agricultural Medicine: Occupational and Environmental Health for Rural Health Professionals course in the state of Iowa in the USA or the Agricultural Health and Medicine course in the state of Victoria in Australia between 2010 and 2013 (inclusive). Data were analysed using descriptive statistics, frequencies and the &#967;2 test. Students were invited to make any other comments regarding the course.

RESULTS

One hundred and ten students completed the survey (59 from the USA and 51 from Australia) with over a 50% response from both countries, indicating the high level of commitment to this discipline. Responses were consistent across both continents, with more than 91% agreeing that the course improved their abilities to diagnose, prevent and treat rural and agricultural populations. Further, both courses successfully enabled a multidisciplinary and cross-sectoral approach to agricultural health and medicine.

CONCLUSIONS

More than 72% of previous students were practising in rural and /or mixed communities at the time of the survey, demonstrating a repeatable and transferable medical education program that supports multidisciplinary care and scholarship while addressing health inequities in agricultural populations. Findings from this study indicate there are opportunities to expand globally.

Detection of Airborne Methicillin-Resistant Staphylococcus aureus Inside and Downwind of a Swine Building, and in Animal Feed: Potential Occupational, Animal Health, and Environmental Implications

Aerosolized methicillin-resistant Staphylococcus aureus (MRSA) was sampled inside and downwind of a swine facility. Animal feed was sampled before and after entry into the swine facility. Aerosolized particles were detected using an optical particle counter for real-time measurement and with an Andersen sampler to detect viable MRSA. Molecular typing and antimicrobial susceptibility testing were performed on samples collected. Viable MRSA organisms isolated inside the swine facility were primarily associated with particles >5 µm, and those isolated downwind from the swine facility were associated with particles <5 µm. MRSA isolates included spa types t008, t034, and t5706 and were resistant to methicillin, tetracycline, clindamycin, and erythromycin. Animal feed both before and after entry into the swine facility tested positive for viable MRSA. These isolates were of similar spa types as the airborne MRSA organisms. Air samples collected after power washing with a biocide inside the swine facility resulted in no viable MRSA organisms detected. This pilot study showed that the ecology of MRSA is complex. Additional studies are warranted on the maximum distance that viable MRSA can be emitted outside the facility, and the possibility that animal feed may be a source of contamination.

Agricultural-Related Injury and Illness in The Gambia

This is an exploratory, descriptive study based on a convenience sample from a rural nursing service and in-country area farmers from The Gambia. The purpose of the study was to provide descriptive information about agricultural-related injury and illness from area farmers and to obtain data from rural nurses about the time they spent caring for and treating farmers. Employees of the nursing service could read and write English fluently and thus completed a written questionnaire; the area farmers were unable to read and write English so they were interviewed by farm extension workers in their own tribal language. The most alarming findings were the nursing respondents' report of farm workers using pesticides in their homes, the poor condition of pesticide sprayers, and the lack of personal protective equipment. Despite their claim of following pesticide instructions, farm workers reported a surprisingly high number of respiratory and neurological signs and symptoms.

Prevalence of Musculoskeletal Symptoms and Predictors of Seeking Healthcare among Iowa Farmers

Farmers experience musculoskeletal symptoms such as pain and disability at a higher rate than other professions, yet little is known about the associated environmental and health factors. The objective of this research is to describe health screening data, musculoskeletal symptoms, and farm safety environmental scores to determine the relationships among these variables for Midwest famers. The sample (n = 438) included farmers from 38 counties that surround ten AgriSafe clinic sites in Iowa who were principal farm operators and/or spouses, farmed at least 20 hours per week on average, and had agricultural production of at least $1,000 in sales a year. Musculoskeletal symptom prevalence varied by age and joint, with the lowest prevalence of 28% for the elbow and the highest prevalence of over 73% for the lower back. The average number of painful joints was 4.15 (SD = 2.75) over the last year, with significantly more older farmers experiencing knee pain. Of farmers in the older age category (N = 223), 144 (64.6%) were in the low safety category (safety score ≤ 95). Significant predictors of seeking healthcare due to musculoskeletal symptoms included doctor-diagnosed arthritis (OR = 1.742; 95% CI: 1.024-2.963), employee help on the farm (OR = 2.162; 95% CI: 1.254-3.727), hip pain (OR = 2.959; 95% CI: 1.751-5.001), and upper back pain (OR = 2.036; 95% CI: 1.204-3.443). Health and safety professionals can use a standardized health and safety checklist to identify areas of concern and increase the safety and health of farmers.

The Efficiency of Biofilters at Mitigating Airborne MRSA from a Swine Nursery

Our prior studies have been in agreement with other researchers in detecting airborne methicillin-resistant Staphylococcus aureus (MRSA) inside and downwind of a swine housing facility. MRSA emitted in the exhaust air of swine facilities creates a potential risk of transmission of these organisms to people in the general area of these facilities as well as to other animals. This study investigated a possible means of reducing those risks. We investigated the efficiency of biofilters to remove MRSA from the exhaust air of a swine building. Two types of biofilter media (hardwood chips and western red cedar shredded bark) were evaluated. Efficiency was measured by assessing both viable MRSA (viable cascade impactor) and dust particles (optical particle courter) in the pre-filtered and post-filtered air of a functioning swine production facility. Our study revealed that hardwood chips were respectively 92% and 88% efficient in removing viable MRSA and total dust particles. Western red cedar was 95% efficient in removing viable MRSA and 86% efficient in removing dust particles. Our findings suggest that biofilters can be used as effective engineering controls to mitigate the transmission of aerosolized MRSA in the exhaust air of enclosed swine housing facilities.

Increasing the number of trained health and safety professionals in agricultural medicine: evaluation of the "building capacity" program, 2007-2013

ABSTRACT The University of Iowa began training health care professionals to care for farmers' occupational health needs since 1974. In order to geographically expand this training to practicing health and safety professionals, the "Building Capacity: A National Resource of Agricultural Medicine Professionals" program was developed and launched in 2006. The model began in 1987 as a program of Iowa's Center for Agricultural Safety and Health. In 2006, with funding from the National Institute for Occupational Safety and Health (NIOSH), Great Plains Center for Agricultural Health (GPCAH), the program was expanded beyond the Iowa borders. The principal component of the program, the 40-hour course, Agricultural Medicine: Occupational and Environmental Health for Rural Health Professionals-the Core Course (AMCC) is now being offered to health and safety professionals in nine states in the United States, in Australia, and a modified version presented in Turkey. An initial paper evaluated the first phase of the program, years 2007-2010. This paper compares the first phase (2007-2010) with the second phase (2011-2013), which has involved over 500 health and safety professionals. This paper also describes evaluation of the course and changes resulting from the evaluation. Finally, this paper describes best practices for operating this program and makes recommendations for future courses, as well as other trainings within the field.

Task-based noise exposures for farmers involved in grain production

Few studies have been done examining noise exposures associated with agricultural tasks. This study was conducted to address that research gap by calculating the noise exposures for tasks and equipment associated with grain production and assessing the variability in those exposures. An additional aim of this study was to identify tasks and equipment that could be targeted for intervention strategies as a means toward reducing the total noise exposures of farmers and farm workers. Through the use of personal noise dosimetry and direct observation, over 30,000 one-minute noise exposure measurements and corresponding task and equipment data were collected on 18 farms and compiled into a task-based noise exposure database. Mean noise exposures were calculated for 23 tasks and 18 pieces of equipment. The noise exposures for the tasks and equipment ranged from 78.6 to 99.9 dBA and from 80.8 to 96.2 dBA, respectively, with most of the noise exposures having a large standard deviation and maximum noise exposure level. Most of the variability in the task and equipment noise exposures was attributable to within-farm variations (e.g., work practices, distance from noise sources). Comparisons of the mean noise exposures for the agricultural tasks and equipment revealed that most were not statistically different. Grain production tasks and equipment with high mean noise exposures were identified. However the substantial variability in the noise exposures and the occurrence of intense noise measurements for nearly every task and piece of equipment indicate that targeting a few specific tasks or equipment for intervention strategies would reduce lifetime noise exposure but would not completely eliminate exposure to hazardous noise levels.

Modifiable risk factors for depressed mood among farmers

BACKGROUND

Risk for depression among farmers is not fully understood. DSM-IV considers sadness or depressed mood a critical symptom of depression. The aim of this study was to examine risk factors for depressed mood among farmers using a longitudinal study design.

METHODS

Participants were principal farm operators in the Iowa Certified Safe Farm study. We identified risk factors for depressed mood by calculating relative risks (RR) using the generalized estimating equations method.

RESULTS

In the multivariate model, pesticide exposure (RR = 1.26; 95% CI: 1.04 to 1.53), having an additional job off the farm (RR = 1.32; 95% CI: 1.08 to 1.62), stress (RR = 3.09; 95% CI: 2.55 to 3.75), and previous injury (RR = 1.41; 95% CI: 1.05 to 1.89) prospectively increased the risk of depressed mood.

CONCLUSIONS

Consistent with earlier non-longitudinal studies, the results of this study suggest that reducing pesticide exposure, stress, and injury may reduce the risk of depression in the farm setting.

MRSA in pork production shower facilities: an intervention to reduce occupational exposure

Methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization has been documented in swine and swine workers. MRSA has also been found in the shower facilities of conventional swine farms. We previously conducted a review of the literature to identify measures used to reduce MRSA prevalence in athletic facilities. In this study, we evaluated those measures for adaptability to the pork production environment. A best practices protocol was developed to reduce MRSA levels in pork production shower facilities and implemented in two conventional swine production systems.

Agricultural medicine core course: building capacity for health and safety professionals

In 1987 the University of Iowa began training health care professionals to care for farmers' occupational health needs. The training enables health professionals from various disciplines to function in the anticipation, diagnosis, treatment, and prevention of occupational illnesses and injuries in the farm community. A grant from National Institute for Occupational Safety and Health (NIOSH) entitled "Building Capacity for Health and Safety Professionals" allowed for the expansion of this training to other states. This paper describes the challenges, successes, and lessons learned from dissemination of Agricultural Medicine Core Course.

Community and occupational health concerns in pork production: a review

Public concerns relative to adverse consequences of large-scale livestock production have been increasingly voiced since the late 1960s. Numerous regional, national, and international conferences have been held on the subject since 1994. This paper provides a review of the literature on the community and occupational health concerns of large-scale livestock production with a focus on pork production. The industry has recognized the concerns of the public, and the national and state pork producer groups are including these issues as an important component of their research and policy priorities. One reason large-scale livestock production has raised concern is that a significant component of the industry has separated from traditional family farming and has developed like other industries in management, structure, and concentration. The magnitude of the problem cited by environmental groups has often been criticized by the pork production industry for lack of science-based evidence to document environmental concerns. In addition to general environmental concerns, occupational health of workers has become more relevant because many operations now are employing more than 10 employees, which brings many operations in the United States under the scrutiny of the US Occupational Safety and Health Administration. In this paper, the scientific literature is reviewed relative to the science basis of occupational and environmental impacts on community and worker health. Further, recommendations are made to help promote sustainability of the livestock industry within the context of maintaining good stewardship of our environmental and human capital.

A task-specific assessment of Swine worker exposure to airborne dust

A task-based analysis of personal airborne dust exposures was performed in two swine confinement facilities used to house sows and their litters. Airborne particulate levels were assessed during summer, winter, and spring. Personal aerosol measurements of workers were made with a photometer every 15 sec and corrected to compare with an integrated concentration measurement made with a co-located IOM inhalable dust sampler. Task type and time period were recorded by the workers over an 8-hr work shift. There was a significant difference in dust concentrations between seasons (p < 0.001), with winter months providing the highest levels (geometric mean = 3.76 mg/m(3)). The application of a general linear model of log-transformed task concentrations relative to site, season, and task demonstrated significant differences (P < 0.001) among all three covariates. Tasks performed near moving animals, especially the weaning process, resulted in the greatest concentrations. These results indicate the need to evaluate the concentration levels for separate tasks during multi-task work shifts, such as swine rearing, to optimize efforts to minimize exposures by focusing on high-concentration tasks.

Self-reported methicillin-resistant Staphylococcus aureus infection in USA pork producers

Pork producers selected from the National Pork Board`s producer database were surveyed. Five (3.7%) reported being diagnosed with a MRSA infection. Risk factors related to swine farm biosecurity were examined. None were statistically significant predictors of MRSA infection.

The changing face of agricultural health and safety--alternative agriculture

Alternative agriculture (defined as any production that is not commodity production) is an important growing area of agriculture. The produce ranges widely, from organic products, locally grown products, and exotic crops and animals. This conference included an overview of the evolving field of alternative agriculture plus descriptions of three different alternative agricultural operations, by the actual producers. These producers described the health and safety concerns encountered in their operations. Affordable and accessible health care was a common and very important concern of all these producers. Further, the extensive manual work load is extremely challenging, risking mental and physical stress and burnout. The major occupational health issues were musculoskeletal pain and dysfunction related to the extensive manual labor. Producers presented several suggestions for managing their occupational health issues. It was clear that research is warranted in investigating ergonomic solutions. Further, research and solutions to affordable and accessible health care is a priority issue.

Risk factors for serious injury in Finnish agriculture

BACKGROUND

Previous studies indicate 20% of injuries represent 80% of injury costs in agriculture. To help prevent the most costly injuries, we aimed to identify characteristics and risk factors associated with serious injuries.

METHODS

We analyzed insurance records of 93,550 self-employed Finnish farmers. We ranked injury causes by claim cost and used multiple logistic regressions to identify risk factors for (any) injury and serious injury (injuries exceeding claim costs of 2000 euros).

RESULTS

A total of 5,507 compensated injuries occurred in 2002 (rate 5.9/100 person-years), and 1,167 or 21% of them (rate 1.25/100 person-years) were serious. The causes/sources resulting in highest average claim costs were motor vehicles; stairs, scaffoldings, and ladders; trailers and wagons; floors, walkways, and steps; other structures and obstacles; augers, mills, and grain handling equipment; horses; combines and harvesting equipment; tractor steps; and uneven and slippery terrain. Older age, male gender, higher income level, greater field size, residing on the farm, Finnish language (vs. Swedish), occupational health service (OHS) membership, and animal production were risk factors for injury. The risk factors for serious injury were similar; however, the effects of age, income level, and the raising of horses were more prominent. Language, residence, ownership status, and OHS membership were not risk factors for serious injury.

CONCLUSIONS

Cost-effective prevention efforts should address the following risk factors: older age, male gender, larger income and operation size, livestock production (particularly dairy, swine, and horses), motor vehicle incidents, falls from elevation, and slips, trips and falls.

Pesticide handling and exposures among cotton farmers in the gambia

OBJECTIVES

There are substantial health hazards to farmers and the environment associated with pesticide use in developing countries. Based on observations by the authors and previous reports, most previous studies in Africa are descriptive in nature. The aim of this study was to investigate how cotton farmers are exposed to pesticides in The Gambia and quantify their pesticide exposures and provide information for the formulation of a policy on pesticide safety for the country.

METHODS

A representative sample of 20 cotton farmers in the Central and Upper River Divisions (CRD and URD) of The Gambia were surveyed by questionnaires. Dermal pesticide exposures among a subset of 10 farmer/pesticide applicators were assessed by dermal patch samples, observation, and postapplication questionnaires.

RESULTS

The study revealed that a toxic organochlorine insecticide, Callisulfan (endosulfan), is frequently sprayed on cotton plants by the farmers. The farmers wore no protective equipment and were inadequately dressed for work with this pesticide. Laboratory analysis of the mixed formulation showed a wide range in the concentration of the pesticide solution among the farmer/pesticide applicators and dermal patch samples showed very high residues of endosulfan analytes on their body surfaces.

CONCLUSIONS

A low level of awareness of pesticide toxicity prevails amonsg cotton farmers in The Gambia. There is a less than adequate control of pesticides and other hazardous agrichemicals in the country.

Geocoding accuracy and the recovery of relationships between environmental exposures and health

Background

This research develops methods for determining the effect of geocoding quality on relationships between environmental exposures and health. The likelihood of detecting an existing relationship – statistical power – between measures of environmental exposures and health depends not only on the strength of the relationship but also on the level of positional accuracy and completeness of the geocodes from which the measures of environmental exposure are made. This paper summarizes the results of simulation studies conducted to examine the impact of inaccuracies of geocoded addresses generated by three types of geocoding processes: a) addresses located on orthophoto maps, b) addresses matched to TIGER files (U.S Census or their derivative street files); and, c) addresses from E-911 geocodes (developed by local authorities for emergency dispatch purposes).

Results

The simulated odds of disease using exposures modelled from the highest quality geocodes could be sufficiently recovered using other, more commonly used, geocoding processes such as TIGER and E-911; however, the strength of the odds relationship between disease exposures modelled at geocodes generally declined with decreasing geocoding accuracy.

Conclusion

Although these specific results cannot be generalized to new situations, the methods used to determine the sensitivity of results can be used in new situations. Estimated measures of positional accuracy must be used in the interpretation of results of analyses that investigate relationships between health outcomes and exposures measured at residential locations. Analyses similar to those employed in this paper can be used to validate interpretation of results from empirical analyses that use geocoded locations with estimated measures of positional accuracy.

Injury and Illness Costs in the Certified Safe Farm Study

CONTEXT

The Certified Safe Farm (CSF) intervention program aims to reduce occupational injuries and illnesses, and promote wellness to reduce health care and related costs to farmers, insurers, and other stakeholders.

PURPOSE

To evaluate the cost effectiveness of CSF.

METHODS

Farms (316) located in a 9-county area of northwestern Iowa were recruited and randomized into intervention and control cohorts. Intervention farms received occupational health screenings, health and wellness screening, education, on-farm safety reviews, and performance incentives. For both cohorts, quarterly calls over 3 years were used to collect self-reported occupational injury and illness information, including costs to the farmers and their insurers.

FINDINGS

Annual occupational injury and illness costs per farmer paid by insurers were 45% lower in the intervention cohort ($183) than in the control cohort ($332). Although out-of-pocket expenses were similar for both cohorts, combined costs of insurance and out-of-pocket expenses were 27% lower in the intervention cohort ($374/year per farmer) compared to the control cohort ($512/year per farmer). Within the cohort of intervention farmers, annual occupational injury and illness cost savings were directly associated with on-farm safety review scores. Reported health care costs were $237 per farmer in the safest farms (those farms scoring in the highest tertile) versus $485 per farmer in the least safe farms (lowest tertile).

CONCLUSIONS

Results suggest that farmers receiving the intervention had lower health care costs for occupational injuries and illnesses than control farmers. These cost savings more than cover the cost of providing CSF services (about $100 per farm per year).

Community health and socioeconomic issues surrounding concentrated animal feeding operations

A consensus of the Workgroup on Community and Socioeconomic Issues was that improving and sustaining healthy rural communities depends on integrating socioeconomic development and environmental protection. The workgroup agreed that the World Health Organization's definition of health, "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity," applies to rural communities. These principles are embodied in the following main points agreed upon by this workgroup. Healthy rural communities ensure a) the physical and mental health of individuals, b) financial security for individuals and the greater community, c) social well-being, d ) social and environmental justice, and e) political equity and access. This workgroup evaluated impacts of the proliferation of concentrated animal feeding operations (CAFOs) on sustaining the health of rural communities. Recommended policy changes include a more stringent process for issuing permits for CAFOs, considering bonding for manure storage basins, limiting animal density per watershed, enhancing local control, and mandating environmental impact statements.

Are swine workers in the United States at increased risk of infection with zoonotic influenza virus?

BACKGROUND

Pandemic influenza strains originate in nonhuman species. Pigs have an important role in interspecies transmission of the virus. We examined multiple swine-exposed human populations in the nation's number 1 swine-producing state for evidence of previous swine influenza virus infection.

METHODS

We performed controlled, cross-sectional seroprevalence studies among 111 farmers, 97 meat processing workers, 65 veterinarians, and 79 control subjects using serum samples collected during the period of 2002-2004. Serum samples were tested using a hemagglutination inhibition assay against the following 6 influenza A virus isolates collected recently from pigs and humans: A/Swine/WI/238/97 (H1N1), A/Swine/WI/R33F/01 (H1N2), A/Swine/Minnesota/593/99 (H3N2), A/New Caledonia/20/99 (H1N1), A/Panama/2007/99 (H3N2), and A/Nanchang/933/95 (H3N2).

RESULTS

Using multivariable proportional odds modeling, all 3 exposed study groups demonstrated markedly elevated titers against the H1N1 and H1N2 swine influenza virus isolates, compared with control subjects. Farmers had the strongest indication of exposure to swine H1N1 virus infection (odds ratio [OR], 35.3; 95% confidence interval [CI], 7.7-161.8), followed by veterinarians (OR, 17.8; 95% CI, 3.8-82.7), and meat processing workers (OR, 6.5; 95% CI, 1.4-29.5). Similarly, farmers had the highest odds for exposure to swine H1N2 virus (OR, 13.8; 95% CI, 5.4-35.4), followed by veterinarians (OR, 9.5; 95% CI, 3.6-24.6) and meat processing workers (OR, 2.7; 95% CI, 1.1-6.7).

CONCLUSIONS

Occupational exposure to pigs greatly increases workers' risk of swine influenza virus infection. Swine workers should be included in pandemic surveillance and in antiviral and immunization strategies.

Cost of Compensated Injuries and Occupational Diseases in Agriculture in Finland

Although agriculture is one of the most hazardous industries, the costs of agricultural injuries and illnesses are not well known. This study aimed to determine the cost burden from compensated injuries and occupational diseases in Finnish agriculture using workers compensation records. The incidence rates in 1996 were 7.4/100 for injuries and 0.61/100 for occupational diseases. Men had a higher risk of injury (RR = 1.89; 95% CI: 1.81-1.97), but a lower risk of an occupational disease (RR = 0.68; 95% CI: 0.60-0.78), compared to women. The total cost burden was 75 (Euros) per person in 1983, increasing to 215 in 1999. The total insurance cost in 1996 was 23.5 million consisting of medical care (16%), per diem (lost time compensation within one year from the incident) (37%), pension (lost time compensation after one year from the incident) (23%), survivors pension (3%), impairment allowance (7%), rehabilitation (6%), and other costs (9%). The total cost was 0.7% of the national gross farm income and 2.2% of the net farm income. The mean cost of 1996 cases was 1340 for injuries and 6636 for occupational diseases. Injuries represented 92% of the claims and 71% of the total costs. Occupational diseases represented 8% of the claims and 29% of the costs. Twenty percent of the most severe claims represented 79.5% of the total insurance costs. Injuries and occupational diseases result in significant costs in agriculture. Lost time was the largest cost item. Overall, injuries were more costly than occupational diseases. This study indicates that the 20%-80% rule applies to agricultural injury and illness costs, and from the cost standpoint, it is important to focus prevention efforts on the most severe incidents.

Interlaboratory evaluation of endotoxin analyses in agricultural dusts--comparison of LAL assay and mass spectrometry

Endotoxin exposure is associated with wheeze and asthma morbidity, while early life exposure may reduce risk of allergy and asthma. Unfortunately, it is difficult to compare endotoxin results from different laboratories and environments. We undertook this study to determine if lipopolysaccharide (LPS) extraction efficiency could account for differences among laboratories. We generated and collected aerosols from chicken and swine barns, and corn processing. We randomly allocated side-by-side filter samples to five laboratories for Limulus assay of endotoxin. Lyophilized aliquots of filter extracts were analyzed for 3-hydroxy fatty acids (3-OHFAs) as a marker of LPS using gas chromatography-mass spectrometry. There were significant differences in endotoxin assay and GC-MS (LPS) results between laboratories for all dust types (p < 0.01). Patterns of differences between labs varied by dust type. Relationships between assay and GC/MS results also depended on dust type. The percentages of individual 3-OHFA chain lengths varied across labs (p < 0.0001) suggesting that each lab recovered a different fraction of the LPS available. The presence of large amounts of particle associated LPS and absence of a freezing thawing cycle were associated with lower correlations between LPS and bioactivity, consistent with an absence of Limulus response to cell-bound endotoxin. These data suggest that extraction methods affect endotoxin measurements. The LAL methods may be most suitable when comparing exposures within similar environments; GC-MS offers additional information helpful in optimizing sample treatment and extraction. GC-MS may be of use when comparing across heterogeneous environments and should be considered for inclusion in future studies of human health outcomes.

Hearing loss as a risk factor for agricultural injuries

BACKGROUND

Previous studies suggested that hearing impairment based on self-report might increase the risk of agricultural injuries. However, self-reported hearing measures may be subject to inaccuracy and subjective perception. We assessed the association of agricultural injuries with hearing loss and other hearing characteristics using measured hearing.

METHODS

Study subjects were 150 farmers who participated in the Iowa Certified Safe Farm study. Injury information was collected by telephone interviews at 2-5 month intervals from September 1999 to October 2002. Hearing levels were measured annually using the pure tone audiometry from 1998 to 2002. Adjusted rate ratios of injuries were calculated using the multivariate Poisson regression model.

RESULTS

Hearing loss in the better ear (RR = 1.62), hearing asymmetry (RR = 1.67), and fair/poor self-reported hearing (RR = 1.96) were significantly associated with the risk of agricultural injuries. It is notable that self-reported hearing might be a stronger predictor of injuries than pure tone audiometry (PTA). Exposure to noise elevated the risk of injuries in those farmers with hearing loss or hearing asymmetry. The occasional use of hearing protection was significantly associated with agricultural injuries.

CONCLUSIONS

This study adds substantial evidence that hearing loss acts as a risk for agricultural injuries. Prevention of hearing loss and noise exposure may be important in reducing the burden of agricultural injuries.

Effects of premium discount on workers' compensation claims in agriculture in Finland

BACKGROUND

The objective of this study was to measure changes in injury claim rates after a premium discount program was implemented in the Finnish farmers' workers' compensation insurance. We focused on measures that could indicate whether the changes occurred in the true underlying injury rate, or only in claims reporting.

METHODS

Monthly injury claim rates were constructed at seven disability duration levels from January 1990 to December 2003. We conducted interrupted time series analyses to measure changes in the injury claim rates after the premium discount was implemented on July 1, 1997. Three additional policy change indicators were included in the analyses.

RESULTS

The overall injury claim rate decreased 10.2%. Decreases occurred at four severity levels (measured by compensated disability days): 0 days (16.3%), 1-6 days (14.1%), 7-13 days (19.5%), and 14-29 days (8.4%). No changes were observed at higher severity levels. Minor injuries had a seasonal pattern with higher rates in summer months while severe injuries did not have a seasonal pattern.

CONCLUSIONS

The premium discount decreased the overall claim rate. Decreases were observed in all categories up to 29 disability days. This pattern suggests that under-reporting contributes to the decrease but may not be the only factor. The value of the premium discount is lower than the value of a lost-time claim, so there was no financial reason to under-report lost-time injuries. Under-reporting would be expected to be greatest in the 0 day category, but that was not the case. These observations suggest that in addition to under-reporting, the premium discount may also have some preventive effect.

What's in a name? Revisited: terms used to describe activities related to the health and safety of agricultural-associated populations and consumer

The fundamental role of an academic journal is to facilitate a dialogue among scholars to advance the knowledge and art of practice related to the journal's subject, and consequently, to raise the human condition. As the Journal of Agromedicine begins to chart a course under new management and to enlarge the numbers of contributing scholars and sustaining subscribers, the editor has discovered a variety of concepts, historical developments, and terms used by scholars and practitioners in pursuit of health and safety of agriculture-associated populations and consumers. Each of these concepts, developments, and terms reflect the interests of different scholars and practitioners, who represent a surprisingly broad set of disciplines committed to this large endeavor.

Respiratory symptoms and airway obstruction in swine veterinarians: a persistent problem

OBJECTIVE

There are many occupational hazards associated with the practice of swine veterinarians. To reassess the prevalence of respiratory complaints and pulmonary function abnormalities in this group.

METHODS

This was a cross-sectional study conducted during the American Association of Swine Veterinarians annual meeting. Subjects completed a respiratory symptom/work history questionnaire and performed spirometry.

RESULTS

Participants included 122 veterinarians (median age=42.5 years). Work-related symptoms included rhinitis symptoms (69%), cough and chest tightness (53%), wheezing (31%). Airway obstruction was seen in 24% of participants. Veterinarians with airway obstruction reported working more hours per week in hog barns than did practitioners with normal pulmonary function (P=0.009).

CONCLUSIONS

Respiratory symptoms were common in the swine veterinarians tested as was airway obstruction. The association with these findings and hog barn exposure suggests that working in these facilities is still a risk factor for airway disease.

Acute toxic pneumonitis complicating chronic obstructive pulmonary disease (COPD) in a farmer

BACKGROUND

Toxic pneumonitis or Organic Dust Toxic Syndrome (ODTS) is a common, usually self-limiting condition among agricultural workers, occurring after high level exposure to agricultural dust.

CASE REPORT

We describe the case of a 68-year-old smoker and farmer who became ill with dyspnea, flu-like symptoms, and hypoxia after cleaning out a grain bin.

RESULTS

Chest radiograph was normal. He was treated with steroids, antibiotics, and oxygen supplementation and recovered over 3 months, but continues with lingering exercise intolerance after 2 years.

DISCUSSION

Although toxic pneumonitis usually follows a relatively benign course with spontaneous recovery and no permanent sequale it can lead to the exacerbation of underlying lung conditions, resulting in incomplete or delayed recovery. Prevention is aimed at limiting exposure by avoidance, by increasing ventilation in closed spaces and by appropriate use of personal protective equipment.

Vegetable Oil Sprinkling as a Dust Reduction Method in Swine Confinement

The aim of this project was evaluate the effectiveness of an oil sprinkling system as a dust-reduction method for swine production facilities. This article presents the results of the second-year experiment of a multi-year study. The first-year experiment demonstrated that a 5% oil-water emulsion automatically applied at the rate of 3 and 5 g/pig/day achieved a 23% to 34% reduction in total dust. The modifications for the second year experiment included: (1) increasing oil application rate to 7 and 8 g/pig/day, (2) replacing sprinkler heads to achieve a smaller droplet size and a more direct spray pattern on pen-floor surfaces, and (3) more closely matching the treatment and control rooms by stage in the pig production cycle. Four swine finishing rooms were used for this study; two were treatment rooms (soybean oil at 7 g/pig/day, and canola oil 8 g/pig/day) and two were control rooms. The treatment rooms had a low-pressure oil-sprinkling system, which sprinkled 5% oil-to-water mixture 12 times per day, 12 s each time. Concentrations of several environmental contaminants were measured. The average total dust concentration in the control rooms was 1.39 mg/m3. The average total dust concentration in the treatment rooms was 0.65 mg/m3. The treatment reduced dust by an average of 52%, (p = 0.0001). There was no difference in the degree of dust control between soybean oil and canola oil. The respirable dust concentrations were very low in all rooms, and there were no significant differences between rooms in ammonia, carbon dioxide, temperature, or humidity.

Injuries in the Iowa Certified Safe Farm Study

The aims of this article are to assess injury characteristics and risk factors in the Iowa Certified Safe Farm (CSF) program and to evaluate the effectiveness of CSF for reducing injuries. This intervention program includes a health screening, on-farm safety review, education, and monetary incentives. Cohorts of farmers in an intervention group (n = 152) and control group (n = 164) in northwestern Iowa were followed for a three-year period. During the follow-up, there were 318 injuries (42/100 person-years), of which 112 (15/100 person-years) required professional medical care. The monetary cost of injuries was $51,764 ($68 per farm per year). There were no differences in the self-reported injury rates and costs between the intervention and control groups. Raising livestock, poor general health, and exposures to dust and gas, noise, chemicals and pesticides, and lifting were among risk factors for injury. Most injuries in this study were related to animals, falls from elevation, slips/trips/falls, being struck by or struck against objects, lifting, and overexertion. Machinery was less prominent than generally reported in the literature. Hurry, fatigue, or stress were mentioned as the primary contributing factor in most injuries. These findings illustrate the need for new interventions to address a multitude of hazards in the farm work environment as well as management and organization of farm work.

Synergistic effects of dust and ammonia on the occupational health effects of poultry production workers

OBJECTIVE

As production methods for livestock and poultry moved towards large industrial-scale confinement facilities, the occupational health community reported risks for respiratory illnesses in workers. Likely, greater risks for respiratory disease will occur with the continuing trend towards full-time confinement workers, who inspire a combination of bioaerosols, particulates, and gases. Although there have been numerous studies on the individual health effects of air contaminants inside confined animal production facilities, there have been no reports on the effects of combined exposures. The objective of this study was to investigate the combined health effects of air contaminants on poultry production workers.

SAMPLE POPULATION

Two hundred and fifty-seven poultry production workers participated in this study. The workers represented various areas of the poultry industry, including turkey growing, broiler production, egg laying, and unloading/shakeling in poultry processing. Worker procedures pulmonary function testing was conducted before and after a four-hour work shift. The work environment was assessed for total and respirable dust, ammonia, endotoxin and CO2. The relationship of simultaneous total dust and ammonia exposures was examined by correlation, logistic modeling, and synergy index calculations.

RESULTS

Synergy between ammonia levels and airborne dust explained up to 43% and 63% of the decline (respectively for Forced Expiratory Volume (FEV) in one second and Forced Expiratory Flow (FEF25-75) in pulmonary function over the work shift. Furthermore, assessing the synergy index indicated the combined effect of dust and ammonia is from 53 to 156% (greater combined than individually). The proportion of health effect due to synergy is 35%-61%.

CONCLUSIONS

Synergy of simultaneous dust and ammonia exposures in a working environment raises the question of redefining exposure limits for organic dust and ammonia when workers are exposed simultaneously to these substances.

CLINICAL RELEVANCE

Control of both dust and ammonia in livestock facilities is extremely important. Lack of control of both these contaminants will increase the risk of respiratory dysfunction to all exposed to this environment, including workers and veterinarians.

Comparison of endotoxin assays using agricultural dusts

Endotoxins from gram-negative bacteria pose a significant respiratory hazard. Establishing dose-response relationships is problematic because there are no standard procedures for sampling and analysis. The goal of this study was to compare endotoxin analyses in six laboratories using Limulus-based assays for analysis of organic dusts from three agricultural environments: chicken barns, swine barns, and corn processing facilities. For each dust generation experiment 14 side-by-side air samples were collected on 37-mm glass fiber filters at flows of 1.8 L/min. Each laboratory was randomly allocated two filters from each of seven experiments per dust type. Three laboratories used the QCL-1000 endpoint assay, and three used the kinetic-QCL method. To eliminate variability among different lots, a single lot of Limulus amebocyte lysate for endpoint assays and one similar lot for kinetic assays was provided. Precision of assays performed within labs was very good, with pooled coefficients of variation for replicate samples ranging from 1 to 11% over all labs and all dust types. There were significant differences between laboratories for all three dust types (p < 0.01). The pattern of differences between labs varied by dust type. For chicken dust, labs using the endpoint method reported higher results than those using kinetic methods. For swine and corn dusts, labs using the kinetic method reported the highest endotoxin values. For chicken dust, results from all labs except A and B were highly correlated (r = 0.86-1.00). For swine dust, only labs B and E, and C and D were correlated. For corn, A, B, and D were significantly correlated with most other labs. In conclusion, statistical differences in performance between laboratories were apparent and may be related to the extraction and analytical methods. The results of this study will be useful for standardization of sampling and analysis of airborne endotoxin in agriculture.

"Agriculture at risk: A report to the nation"--a historical review, critical analysis, and implications for future planning

"Agricultural at Risk: A Report to the Nation" is a proceedings document of a three-year (1987-1990) policy development process entitled "Agricultural Occupational and Environmental Health: Policy Strategies for the Future." That process culminated in the emergence of occupational health and safety in agriculture as a public health policy issue in the U.S. Several agricultural health and safety programs evolved as direct or indirect consequences of this process, including, but not limited to, the NIOSH agricultural occupational health programs, The Kellogg Foundation agricultural health grants programs, and the prospective chronic health studies of pesticides (EPA-NlH funded). The Agriculture at Risk report resulted in 86 specific recommendations. The authors of this article reviewed each of these recommendations and rated them on a subjective scale as to their degree of attainment. They found that 44% of the recommendations had received moderate to substantial action. Most of the positive action was in the areas of research and coalition building. A noticeable lack of action was in the areas of standards and regulation, occupational health service delivery, and education categories. This article concludes with an analysis of the limitations of the AAR report, changes in exposed populations over the past decade, and specific recommendations on future actions to address the issues.

Respiratory symptoms in European animal farmers

Farmers are known to be at high risk for the development of occupational airway disease. The aim of this European study was to determine which airway symptoms predominate in different types of animal farmers (cattle, pigs, poultry, sheep) and to compare the prevalence of symptoms to the general population. A total of 6,156 randomly selected animal farmers in Denmark, Germany (Schleswig-Holstein, Niedersachsen), Switzerland, and Spain completed a questionnaire on respiratory symptoms and farming characteristics in 1995-1997. The prevalence of general respiratory symptoms was compared to the results of the European Community Respiratory Health Survey (ECRHS) obtained in the same regions. Pig farmers were at highest risk for the development of work-related symptoms. A significant dose-response relationship between daily hours worked inside animal houses and symptoms was established for pig and poultry farmers. Additionally, self-reported nasal allergies (odds ratio (95% confidence interval): 3.92 (3.26-4.71)) and nasal irritation during work (3.98 (3.35-4.73)) were shown to be associated with the development of chronic phlegm. The prevalence of wheezing, shortness of breath, asthma and nasal allergies was signficantly lower among all farmers in the age group 20-44 yrs than among the general population. However, the prevalence of usually bringing up phlegm in winter among farmers was significantly higher than in the general population (9.4 (8.3-10.5%) versus 7.5 (6.5-8.5%)). Individual factors have been shown to be related to the prevalence of chronic phlegm among farmers. Additionally, this study could support the hypothesis that farming could be negatively related to allergic diseases.

The concentration of swine production. Effects on swine health, productivity, human health, and the environment

The concern about environmental issues centering around CAFOs is appropriate. The veterinary profession can be an important force in meeting these challenges by broadening its scope of knowledge and practice into the broader environmental field. Although animal agriculture's contribution to environmental concerns is the focus of this article, it is only one of several sectors that contributes to environmental degradation. Crop production, as well as livestock production industries, contribute to pollution. Manufacturing industries, municipalities, private individuals, our consumptive lifestyles, and agriculture all contribute to the degradation of our environment. One must keep in mind the huge importance of our agricultural industry and not single it out to the detriment of its progress. We have an abundance of high-quality foods at the lowest cost to the individual of any industrialized nation. We export over 40 billion dollars in agricultural products yearly. Agriculture sustains our rural economies and provides opportunities for over 2 million private enterprises scattered across the country; however, there is a goal that we have a sustainable agriculture. A big part of that depends on development and enhancement of an agriculture that does not pollute, that sustains its farm operators and workers, and that does not make the area residents ill or degrade their quality of life; however, the current situation is not promising. Much remains to be learned about the actual acute and long-term health consequences of animal agricultural pollution. Many health concerns are speculative, even though based on sound facts. We know that many surface waters have excess N and P that leads to eutrophication and possibly enhanced growth of undesirable organisms such as Pfiesteria piscicida. We know that other animal pathogens, such as cryptosporidia, have caused large community outbreaks. There are other potential pathogens, such as Salmonella sp, for which we do not know the hazard. We know that our soils may become excessively laden with P, Cu, and Zn, which retard plant growth and create toxic conditions for grazing animals. There are concerns about air pollution. Odors have negative sensory and physical health consequences. H2S and dust may cause toxic effects on neighbors. NH3 vaporizing from manure sources may be carried with precipitation to cause eutrophication in lakes or altered ecosystems in natural areas. CH4 escaping from degrading manure contributes to greenhouse gases. Workers in confined livestock structures have high risk for a variety of chronic respiratory conditions. They also are at risk for acute poisoning from H2S in operations where liquid manure is stored in confined spaces. There have been numerous health complaints in recent years from community neighbors of large-scale livestock operations. One study showed adverse altered mood states, and another showed evidence of respiratory illness similar to what workers experience. Although it has not been possible to objectively measure conditions and know toxic levels of substances causing these illnesses, there are so-called extratoxic mechanisms, such as inherent aversion to putrefactive odors and exacerbation of preexisting conditions that lower the tolerance threshold. Environmental concerns regarding livestock production are not new. In the early and mid-1970s, there were many conferences and publications regarding odors and water contamination from livestock operations. Although most of what is known in this area has been known for 20 years, relatively little effective efforts have been made to correct the concerns. In fact, trends over this past decade have increased the concerns. This past decade has seen a tremendous acceleration in the concentration and consolidation of agriculture, capping a slow trend over the past 50 years toward larger, fewer, and more-specialized farms. This trend has gone against the old saying that "dilution is the solution to pollution.

Respiratory symptoms of obstructive lung disease in European crop farmers

Crop farming as a risk factor for respiratory symptoms of obstructive lung disease was assessed. Random samples of crop farmers from four European countries were studied following a cross-sectional design. A questionnaire on respiratory symptoms and occupation was administered to determine prevalences, and the roles of the various crops as risk factors for respiratory symptoms were assessed through logistic regression modeling. The 4,793 crop farmers included in the study (response rate: 85.3%) reported the following respiratory symptoms: wheezing (14.9%), asthma (3.3%), nasal allergy (14.4%), chronic phlegm (12.4%), organic dust toxic syndrome (ODTS) (15.2%), and symptoms at work (22.0%). In the multivariate analysis, adjusting for age, sex, smoking, country, and exposure to other plants or livestock, flower growing was a risk factor for asthma (odds ratio [OR] 2.1, 95% confidence interval [CI] 1.1-3.9) and cultivating oil plants was associated with ODTS (OR 1.5, 95% CI 1.3-1.9), symptoms at work (OR 1.4, 95% CI 1.2- 1.7), and chronic phlegm (OR 1.3, 95% CI 1.1-1.6). Working inside greenhouses was a marginal risk factor for asthma (OR 2.1, 95% CI 0.9-4.5). We conclude that flower and oil plant production is associated with increased risk of respiratory symptoms in European crop farmers.

Dose-response relationships between occupational aerosol exposures and cross-shift declines of lung function in poultry workers: recommendations for exposure limits

Numerous articles have been published regarding the adverse respiratory health consequences of working in intensive livestock and poultry housing. Threshold limit exposure guidelines are not currently applied to this environment, but they are essential to implement and monitor effective environmental controls. Previous dose-response research work with swine workers has resulted in exposure limit recommendations of 2.5 mg/m3 total dust, 0.23 mg/m3 respirable dust, 100 EU/m3 endotoxin, and 7 ppm ammonia. No similar recommendations have been reported previously for poultry workers. Therefore, an industry-wide study was conducted to examine dose-response relationships of bioaerosol exposures and worker respiratory health. A total of 257 poultry workers were studied for respiratory symptoms, pulmonary function, and exposure to dust (total and respirable), endotoxin (respirable and total), and ammonia. Details of the sampling plan and environmental assessment are described elsewhere. Relationships between exposures and response were studied by correlation and multiple regressions. Significant dose-response relationships were observed between exposures and pulmonary function decrements over a work shift. Exposure concentrations associated with significant pulmonary function decrements were as follows: 2.4 mg/m3 total dust, 0.16 mg/m3 respirable dust, 614 EU/m3 endotoxin, and 12 ppm ammonia.

Rural Youth Disability Prevention Project Survey: results from 169 Iowa farm families

Agriculture is now the most hazardous occupation in the United States and it is the only one in which children not only comprise a significant part of the work force, but also live and play at the work site. Annually, 23,500 pediatric agricultural injuries are reported, with nearly 300 fatalities (Rivara, 1985). The Rural Youth Disability Prevention Project was designed to use innovative, community-oriented methods to address the unique problems of child safety in agriculture. Toward this end, a survey instrument was designed to gather data both to assist in program development and to serve as a pretest for the subsequent evaluation. Analysis of these data indicated several issues to target for intervention efforts. One is lack of supervision--more than 40 percent of children who operate equipment do so unsupervised. Approximately 30 percent of children more than 3 years old play alone in work areas, and 80 percent of these children play near machinery in operation. Another issue is operation of farm machinery by very young children--respondents' children began operating equipment at an average age of 12 years. Coupling this with the finding that the parents believe their children are not capable of operating equipment until age 15 exemplifies the most important issue, the disparity between parents' levels of safety knowledge and safety behavior. Using the survey data to increase local involvement, efforts are being directed toward facilitating an ongoing, community-sponsored intervention program to empower farm families to effect their own solutions.

Respiratory tract inflammation in swine confinement workers studied using induced sputum and exhaled nitric oxide

OBJECTIVE

To further define the asthma-like syndrome seen in swine confinement workers.

DESIGN

A cross-sectional study was performed at a swine confinement facility in rural Nebraska and at the University of Nebraska Medical Center, Omaha, Nebraska.

PARTICIPANTS

24 swine confinement workers and 14 urban normal control subjects. All subjects completed a questionnaire concerning respiratory complaints. We performed hypertonic saline challenges on the swine confinement workers and control subjects in order to induce expectoration of sputum. Cell counts and cell differentials were determined in the induced sputum samples. Nasal, mean, and peak exhaled nitric oxide was measured in both groups. Spirometry was also done.

RESULTS

Swine confinement workers were significantly more likely to report wheezing, cough, and sinusitis symptoms than controls (p = .003). Macrophages were significantly elevated in the induced sputum samples of the swine confinement workers vs the control subjects (0.59 macrophages/mL +/- 0.1 SEM vs 0.36 +/- .16; p = .006), while there was no difference in numbers of neutrophils. No eosinophils were observed. A small elevation in mean exhaled nitric oxide was seen in the swine confinement workers compared to normal controls (11.7 ppb +/- 0.6 SEM vs 10.2 +/- 1.6; p = 0.023). Spirometry values did not differ statistically between swine confinement workers and the control group.

CONCLUSIONS

Swine confinement workers have signs and symptoms of lower respiratory tract inflammation when studied using induced sputum and exhaled nitric oxide. Findings in the swine confinement workers differ from those in asthmatics and chronic bronchitis.

Longitudinal evaluation of dose-response relationships for environmental exposures and pulmonary function in swine production workers

Studies describing respiratory health hazards for workers in swine production facilities have been published in the United States, Sweden, Canada, the Netherlands, and Denmark. Up to 50% of these workers experience bronchitis, organic dust toxic syndrome, hyper-reactive airways disease, chronic mucous membrane irritation, and other respiratory effects. These studies clearly point to the fact that this occupational environment poses a significant health risk hazard, and that control methods are needed to protect the worker. Before precise control strategies can be developed, implemented, and evaluated, dose-response studies are required to determine acceptable target levels for exposure. A previous manuscript described the development of multiple regression equations characterizing the relationships between environmental exposures and pulmonary response in a cohort of 207 swine producers. Baseline pulmonary function was included as a significant predictor of cross-shift decrements in pulmonary function in addition to personal measurements of dust, endotoxin, and ammonia concentrations. These equations were then used to predict specific exposure levels of dust and ammonia that could be expected to elicit significant decrements in cross-shift pulmonary function. This paper presents the results from analysis of follow-up data obtained on this same cohort 2 years after the initial measurements. At the second measurement period of the study (time-2), swine workers were found to have a mean cross-shift decrease in FEV1 of 2%. Cross-shift change in FEV1 was significantly correlated with personal exposures to total dust, total endotoxin, respirable endotoxin, and ammonia. The magnitude of the decrease in FEV1 was associated with increasing airborne concentrations of these environmental parameters thus confirming the dose-response relationship observed in the initial study (time-1). The correlation of dust with FEV1 changes in workers with more than 6 years of exposure (time-1 data) and more than 10 years of exposure (time-2 data) suggests that dust exposure is an important factor in chronic respiratory disease. Additionally, the correlation of endotoxins with FEV1 changes in the group with less than 6 years exposure (time-2 data) suggests endotoxins may have more significance for subacute respiratory effects. The agreement between observed cross-shift FEV1 changes measured in time-2 with changes predicted using regression equations derived from time-1 data demonstrates a consistent dose-response relationship over time for this cohort of swine production workers. This finding provides further support for conclusions of the previous study that levels of 2.5 mg/m3 (total dust) and 7.5 ppm (ammonia) are reasonable guidelines for occupational exposure limits in this environment.