L. Stallones, M. Leff, C. Garrett, L. Criswell, T. Gillan
American Society of Agricultural and Biological Engineers (ASABE)
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.
A
number of studies have reported higher suicide rates among agricultural
workers than expected (Guralnick, 1963; Walrath et al., 1985;
Stallones, 1990). Although depression is well known to be associated
with an increased risk of suicide, there is incomplete information
available on the mental health status of agricultural workers.
Depressive symptoms have been reported to be higher among agricultural
workers than among other occupational groups (Sayetta and Johnson,
1980). The role of economic and social change on the risk of
depression has not been studied among agricultural workers.
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.
Table
1. Percentage of rural farm households, registered
farm trucks, and agricultural sales by crop reporting
district in Colorado. |
District
|
|
Farm
Households (%)
| Registered
Farm Trucks (%)
| Agricultural
Sales (%)
|
1 |
28.1 |
31.4 |
48.3 |
2 |
23.7 |
26.2 |
22.8 |
3 |
13.6 |
15.2 |
16.0 |
4 |
5.7 |
7.0 |
4.3 |
5 |
21.0 |
14.0 |
5.0 |
6 |
7.9 |
6.2 |
3.6 |
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.
Table
2. Number of rural farm households and sample
size by crop reporting district. |
District
|
|
Farm
Households in Which a Principal Operator Resides (no.)
| Target
Sample Size
| Actual
Sample Size
|
1 |
5578 |
170 |
159 |
2 |
4713 |
117 |
112 |
3 |
2709 |
68 |
67 |
4 |
1567 |
33 |
33 |
5 |
4176 |
90 |
77 |
6 |
1131 |
28 |
28 |
TOTAL
| 19874 |
500 |
485 |
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 (CESD) scale, social support, and pesticide
exposures. Interviews were designed to take approximately 20
min for the farmer and for the spouse of the farmer.
The
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.
Table
3. Selected characteristics of the study population,
Colorado, 1993. |
Characteristic
|
|
Males
(%) (n = 470)
| Females
(%) (n = 402)
|
Depressed |
Yes |
7.9 |
11.1 |
No |
92.1 |
88.9
|
Race |
White |
98.5 |
98.8 |
Hispanic |
0.43 |
0.25 |
Asian |
0.64 |
0.50 |
American
Indian |
0.43 |
0.50
|
Region |
1 |
31.9 |
34.1 |
2 |
24.9 |
23.4 |
3 |
14.3 |
13.9 |
4 |
5.7 |
5.5 |
5 |
15.1 |
14.9 |
6 |
8.1 |
8.2 |
Income |
<
$40,000 |
44.0 |
45.8 |
$40,000-$99,000 |
23.6 |
20.9 |
>
$99,000 |
29.4 |
30.6 |
Unknown/Refused |
3.0 |
2.7
|
Marital
Status |
Married |
52.4 |
71.0 |
Not
Married |
47.6 |
29.0
|
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 |
Some
college |
23.2 |
23.4 |
College
graduate |
16.4 |
18.4 |
Post
graduate |
6.8 |
8.7
|
Depressed |
Yes |
7.9 |
11.1 |
No |
92.1 |
88.9
|
Involved
in Farm Work |
Yes |
99.4 |
77.6 |
No |
0.6 |
22.4
|
Perceived
Health |
Excellent |
30.0 |
34.8 |
Very
good |
37.9 |
37.6 |
Good |
23.8 |
22.1 |
Fair |
6.2 |
3.5 |
Poor |
2.1 |
2.0
|
Income
Declined |
Yes |
23.7 |
78.0 |
No |
76.3 |
22.0 |
A
total of 485 farms representing 872 individuals were enrolled
in the study. Table 2 contains the sampling distribution by
agricultural region. Table 3 shows the distribution of selected
characteristics of the study population.
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.
Overall
prevalence of depressive symptoms was lower among farm residents
(8% for males; 11% for females) than among the general U.S.
population (11% for males; 21% for females) (Sayetta and Johnson,
1980). Characteristics which have been found to be associated
with high depressive symptoms in other studies which used the
CESD scale include older age, being female, low income, low
educational achievement, poor physical health, and lack of social
support (Comstock and Helsing, 1976; Frerichs et l., 1981; Goldberg
et al.,
Table
4. Unadjusted odds ratios for selected characteristics
associated with high depressive symptoms. |
Characteristic
|
|
Odds
Ratio
| 95%
Confidence Interval
|
Perceived
Health |
Excellent |
1.00 |
|
Very
good |
1.21 |
0.61,
2.41 |
Good |
2.31 |
1.17,4.61 |
Fair |
4.17 |
1.57,
10.93 |
Poor |
5.88 |
1.45,
20.17 |
Gender |
Males |
1.00 |
|
Females
|
1.45 |
0.89,
2.35 |
Marital
Status |
Married |
1.00 |
|
Unmarried |
2.25 |
1.09,
4.59 |
Involved
in Farm Work |
No |
1.00 |
|
Yes |
0.53 |
0.27,
1.04 |
Income
Declined |
No |
1.00 |
|
Yes
to no |
2.61 |
1.58,
4.30 |
1985). In
accord with the other studies, the Colorado farm population
were more likely to have high depressive symptoms if they were
female, in poor physical health, and unmarried. The characteristics
associated with depressive symptoms which did not show the same
pattern of association as in the general population were educational
achievement and age. Younger farmers were more likely to have
high depressive symptoms compared to older farmers. Educational
achievement and income were not associated with depressive symptoms
in this population.
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.
Table
5. Logistic regression analysis of high depressive
symptoms (CESD scale > 15) among farm operators
and their spouses, Colorado 1993*. |
Variable
|
|
Regression
Coefficient
| Chi-square
| P-value
|
Intercept |
:1.39 |
|
|
Age |
-0.04 |
13.9 |
0.0002 |
Reduction
in income |
0.91 |
12.3 |
0.0004 |
Marital
status |
0.93 |
6.2 |
0.0128 |
Involved
in farm work |
-0.82 |
6.0 |
0.0140 |
Perceived
health |
0.53 |
19.2 |
0.0001 |
*
n = 857. |
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.
- Bowers,
M. B., E. Goodman and V. M. Sim. 1964. Some behavioral changes
in man following anticholinesterase administration. J.
of Nervous and Mental Disease 138(4):383-389.
- Colorado
Agricultural Statistics Service. 1990. Colorado Agricultural
Statistics, 1989. USDA, NAS, Colorado Dept. of Agriculture,
July (2).
- Comstock
G. W. and K. J. Helsing. 1976. Symptoms of depression in
two communities. Psychological Medicine 6(6):551-563.
- Frerichs
R. R., C. S. Aneshensel and V. A. Clark. 1981. Prevalence
of depression in Los Angeles County. Am. J. of Epidemiology
113(6):691-699.
- Goldberg
E. L., P. Van Natta and G. W. Comstock. 1985. Depressive
symptoms, social networks and social support of elderly
women. Am. J. of Epidemiology 121:448-456.
- Guralnick,
L. 1963. Mortality by industry and cause of death among
men 20 to 64 years of age: United States, 1950. Vital
Statistics Special Reports September.
- Hayes,
W. J. 1982. Pesticides Studied in Man. Baltimore,
Md.: Williams and Wilkins.
- Division
of Motor Vehicles, Colorado Dept. of Revenue. 1991. Motor
Vehicle Statistical Report, Publication 16. July.
- Levin,
H. S., R. L. Rodnitzky and D. L. Mick. 1976. Anxiety associated
with exposure to organophosphate compounds. Archives
of General Psychiatry 33(2): 225-228.
- Murrell
S. A., S. Himmelfarb and W. Wright 1983. Prevalence of depression
and its correlates in older adults. Am. J. of Epidemiology
117(2):173-185.
- Radloff
L. S. 1977. The CES-D scale: A self report depression scale
for research in the general population. Applied Psychological
Measurement 1(3):385-401.
- Robert
R. E. 1980. Reliability of the CES-D Scale in different
ethnic contexts. Psychiatry Research 2(2):125-134.
- Sayetta
R. B. and D. P. Johnson. 1980. Basic data on depressive
symptomatology, United States, 1974-75 DHEW Publication
No. PHS 80-1666. Washington, D.C.: GPO.
- Senanayake,
N. and L. Karalliedde. 1987. Neurotoxic effects of organophosphorus
insecticides. New England J. of Medicine 316(13):761-763.
- Stallones,
L. 1990. Suicide mortality among Kentucky farmers, 1979-1985.
Suicide and Life Threatening Behavior 20(2):156-163.
- U.S.
Dept. of Commerce, Bureau of the Census. 1989. 1987, Census
of Agriculture, Vol. 1, Geographic Area Series, Part
6 Colorado.
- Vernon
S. W. and R. E. Roberts. 1982. Prevalence of treated and
untreated psychiatric disorders in three ethnic groups.
Soc. Sci. Med. 16(17):1575-1582.
- Walrath,
J., E. Rogot, J. Murray and A. Blair. 1985. Mortality patterns
among U.S. veterans by industry and smoking status. DHHS
Publication No 85-2747. Washington, D.C.: GPO.
- Weissman
M. M., D. Sholomskas, M. Pottenger, B. A. Prushoff and B.
Z. Locke 1977. Assessing depressive symptoms in five psychiatric
populations: A validation study. Am. J. of Epidemiology
106(3):203-214.
Disclaimer
and Reproduction Information: Information in NASD does not
represent NIOSH policy. Information included in NASD appears
by permission of the author and/or copyright holder. More
NASD Review: 04/2002
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.
|