Previous studies have reported farmers to be at higher risk of suicide compared to other workers. In order to determine possible correlates of suicide, a study including assessment of depressive symptoms was undertaken in Colorado. The purpose of this article is to describe depressive symptoms among a representative sample of Colorado farm operators and their spouses. A stratified sample of farms in Colorado was selected for study. Detailed questionnaires were administered by telephone interview assessing general health, farm characteristics, demographics, hazards, injuries, behavioral risk factors, safety knowledge, medical care and insurance, mental health using the Center for Epidemiologic Studies Depression Scale, social support, and pesticide exposures. Logistic regression was used to evaluate factors associated with depressive symptoms in this population. A total of 485 farms representing 872 individuals were enrolled in the study. A 9.3% overall prevalence of depressive symptoms was found in the group; 7.9% among males and 1 .1% among females. Factors evaluated in relation to depressive symptoms were age, social support, negative life changes, general physical health, changes in income, and alcohol use. Based on backward elimination, overall assessment of health, gender, social support, and negative life changes were significantly associated with depressive symptoms. Overall prevalence of depressive symptoms was lower in this population from that reported in the general population. Characteristics associated with depressive symptoms in other population studies were also associated with depression in this group. Further work is needed to elucidate factors which affect the overall risk of suicide among farmers.
Keywords. Mental health, Farmers, Depressive symptoms.
Acute neurotoxic effects of pesticide exposure have been well described; they include residual anxiety and depression (Hayes, 1982; Senanayake and Karalliedde, 1987). Cholinesterase inhibitors have been shown to induce depression (Bowers et al., 1964; Levin et al., 1976). Organophosphate compounds and carbamates are commonly used pesticides that are known anticholinesterase substances (Hayes, 1982). Due to chronic exposures to these compounds, there is a need to evaluate the prevalence of depression among exposed workers in agriculture.
More recent population-based data are needed among agricultural workers since there have been many changes in agricultural practices and in social and economic situations for farmers. The purpose of this article is to describe depressive symptoms among a representative sample of Colorado farm operators and their spouses conducted during 1993.
MATERIALS AND METHODS
A stratified probability sample of farms in Colorado was selected for study. A telephone survey was conducted on a sample of Colorado farms during February through April, 1993. The sample was identified through the use of the farm truck registration list available from the Division of Motor Vehicle Registration, Colorado Department of Revenue (Motor Vehicle Department, 1991). This list identified each truck in Colorado that was registered as a farm truck in the past two years. The record for each farm truck contained the names of up to three owners of the vehicle, the legal address, and the mailing address for the vehicle. Farm trucks are registered separately from other types of trucks. In order to register a truck as a farm truck, the owner must make 51% of his or her income from farming land that he or she owns or leases. In addition, the owner must sign an affidavit indicating that the truck is used for farm work and no other commercial purposes. Thus, this sampling frame represents principal farm operators. Other categories of truck registration in Colorado include standard trucks and light trucks. The cost of registration is based on the size of the truck as well as the model and year. In general, the cost of registration for larger farm trucks is less than for standard trucks; the registration cost for smaller farm trucks is slightly lower than the cost for light trucks. Thus, it is economically advantageous to register a truck as a farm truck. Crop reporting districts were developed by the Colorado Agricultural Statistics Service and are used s the basis for reporting agricultural practices in the state (Colorado Agricultural Service, 1990). There are six crop reporting districts in the state. During 1990, the number of vehicles registered as farm trucks was 94,707. District 1 had 5.4 registered farm trucks per resident farm operator household; District 2, 5.3; District 3, 5.3; District 4, 5.9, District 5, 3.2; and District 6, 3.8. Table 1 presents the number of farm resident operator households by agricultural district (Census of Agriculture, 1989), the number of farm trucks registered in each district, and the percent of agricultural sales for each district. This table was used to determine whether there was a biased distribution of farm trucks in any district in relation to the overall agricultural sales or the number of farm households.
|Farm Households (%)||Registered Farm Trucks (%)||Agricultural Sales (%)|
|Farm Households in Which a Principal Operator Resides (no.)||Target Sample Size||Actual Sample Size|
CESD scale contains a series of 20 questions and has been
used in numerous studies (Radloff, 1977; Comstock and Helsing,
1976; Frerichs et al., 1981; Roberts, 1980; Vernon and Roberts,
1982; Murrell et al., 1983; Weissman et al., 1977). The scale
scores range from 0 to 60. The CESD scale has been shown to
be a valid screening tool for detecting depressive symptoms
in general populations and in psychiatric populations (Weissman
et al., 1977). The scale is valid, reliable, and internally
consistent (Roberts, 1980; Vernon and Roberts, 1982). A score
of 16 or higher has been used by other investigators (Frerichs
et al., 1981; Goldberg et al., 1985) to indicate high depressive
symptoms and was used in the analysis of this survey. Variables
which were assessed in relation to depressive symptoms were
gender, age, social support, negative life events, involvement
in farm work, general perception of health status, alcohol
use, and race. Univariate analyses were conducted to identify
important variables for inclusion in t e regression model.
Logistic regression was used to evaluate factors associated
with depressive symptoms in this population. Backward elimination
was used to model the relationships between exposure and outcome.
|Males (%) (n = 470)||Females (%) (n = 402)|
|Years of Education|
|8 or less||5.3||1.2|
|Some high school||3.2||4.2|
|High school graduate/GED||39.6||37.|
|Some technical school||2.5||3.7|
|Technical school graduate||3.0||3.0|
|Involved in Farm Work|
A 9.3% overall prevalence of depressive symptoms was found in the group; 7.9% among males and 11.1% among females. The overall mean score for the CESD scale in this population was 6.1 with a range of scores from 0 to 52 and a standard deviation of 6.8. The mean age for the study population was 47.5 years with a range from 20 to 84 and a standard deviation of 12.9 years. Unadjusted odds ratios for perceived health, comparing fair and poor assessments to those who reported they were in excellent health, very good health, or good health for gender, for farm work, for decreased income, for age, and for marital status are shown in Table 4. Those characteristics which were associated with high depressive symptoms were perceived poor health, being a female, having a decrease in income, being unmarried, and younger age. Being involved in farm work was associated with a lower likelihood of being depressed.
Variables which were entered into the model to assess high depressive symptoms were age, race, gender, marital status, farm income, use of alcohol, reduction in income, involvement with farm work, and perceived health status. Based on backward elimination, overall assessment of age, perceived health status, marital status, being involved in farm work and a reduction in income were significantly associated with depressive symptoms (Table 5). Younger age was associated with higher depressive sym toms. Poor perception of health was associated with higher depressive symptoms. Being unmarried and having had a significant reduction in income were associated with higher depressive symptoms. Being involved in farm work was associated with lower depressive symptoms.
|Odds Ratio||95% Confidence Interval|
|Very good||1.21||0.61, 2.41|
|Involved in Farm Work|
|Yes to no||2.61||1.58, 4.30|
|Reduction in income||0.91||12.3||0.0004|
|Involved in farm work||-0.82||6.0||0.0140|
|* n = 857.|
The finding which may be most controversial was that those individuals who live on the farm and are actively involved in farm work were less likely to have high depressive symptoms compared to those who lived on the farm and were not actively involved in farm work. This is contrary to a pervasive belief that farmers are highly stressed and therefore likely to be at high risk for depression and other mental disorders. This is a cross-sectional study and the relationship between farm work and depression may actually be an indication that those who used to perform farm work and are still living on the farm are more likely to be depressed than those who are currently working. The temporal relationship is not clear between the two correlated variables and should be assessed in greater detail in a prospective study.
Further work is needed to elucidate factors which affect the overall risk of depression and of suicide among farm residents. In particular, attention should be paid to work related stress and job stressors, the difference between geographic isolation and social isolation and the function of social support in this population. Studies which are done among other populations of farmers may well yield different results. This study represents a diverse population of farmers who are involved in many types of agriculture. Economic circumstances in agriculture may well affect different groups of farmers at different times. For example, dairy farming may be suffering a recession while other farmers are not. Therefore, it is important to consider such issues in future evaluation of the relationship between farming as an occupation and depression. The variable used in this study was a reduction in income, but there may be better ways to evaluate stress related to income in this population. There is also a need to better define sources of stress in this occupation.
ACKNOWLEDGMENTS AND REFERENCES
Funding for the project came from the National Institute of Occupational Safety and Health, Centers for Disease Control and Prevention, Cooperative Agreement U04/CCU806060. Appreciation is extended to the NIOSH staff for their interest and involvement with the program.
This document was extracted from the Journal of Ag Safety and Health (Volume 1, Number 1, February 1995). This article was submitted for publication in August 1994; reviewed and approved for publication in December 1994.
Lorann Stallones, Associate Professor, Dept. of Environmental Health, Colorado State University, Fort Collins; Marilyn Leff, Director, Survey Research Unit, Colorado Dept. of Health, Denver; Carol Garrett, Chief, Division of Health Statistics and Vital Records, Colorado Dept. of Health, Denver; Lela Criswell, Doctoral Candidate, Dept. of Environmental Health, Colorado State University, Fort Collins; Terri Gillan, Database Administrator, Survey Research Unit, Colorado Dept. of Health, Denver.
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