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.