Karen M. Semchuk

Parkinson's disease and exposure to agricultural work and pesticide chemicals

This population-based case-control study of 130 Calgary residents with neurologist-confirmed idiopathic Parkinsons disease (PD) and 260 randomly selected age- and sex-matched community controls attempted to determine whether agricultural work or the occupational use of pesticide chemicals is associated with an increased risk for PD. We obtained by personal interviews lifetime occupational histories, including chemical exposure data, and analyzed the data using conditional logistic regression for matched sets. In the univariate analysis, a history of field crop farming, grain farming, herbicide use, or insecticide use resulted in a significantly increased crude estimate of the PD risk, and the data suggested a dose-response relation between the PD risk and the cumulative lifetime exposure to field crop farming and to grain farming. However, in the multivariate analysis, which controlled for potential confounding or interaction between the exposure variables, previous occupational herbicide use was consistently the only significant predictor of PD risk. These results support the hypothesis that the occupational use of herbicides is associated with an increased risk for PD.

Parkinson's disease A test of the multifactorial etiologic hypothesis

We studied the relative etiologic importance upon the development of Parkinsons disease (PD) of occupational exposure to herbicides and other compounds, ionizing radiation exposure, family history of PD and essential tremor, smoking, and history of various viral and other medical conditions. We identified patients (n = 130) with neurologist-confirmed idiopathic PD through contacts with Calgary general hospitals, long-term care facilities, neurologists, the Movement Disorder Clinic, and the Parkinsons Society of Southern Alberta, and selected two matched (by sex and age ± 2.5 years) community controls for each case by random digit dialing. We obtained lifetime work, chemical, radiation, medical, and smoking exposure histories and family histories of PD and essential tremor by personal interviews, and analyzed the data using conditional logistic regression for matched sets. After controlling for potential confounding and interaction between the exposure variables, using multivariate statistical methods, having a family history of PD was the strongest predictor of PD risk, followed by head trauma and then occupational herbicide use. Cases and controls did not differ in their previous exposures to smoking or ionizing radiation; family history of essential tremor; work-related contact with aluminum, carbon monoxide, cyanide, manganese, mercury, or mineral oils; or history of arteriosclerosis, chicken pox, encephalitis, hypertension, hypotension, measles, mumps, rubella, or Spanish flu. These results support the hypothesis of a multifactorial etiology for PD, probably involving genetic, environmental, trauma, and possibly other factors.

Rural families caring for a relative with dementia: barriers to use of formal services

Planning for the care of increasing numbers of elderly persons with dementia has become an urgent health services concern in Canada and elsewhere, yet little is known about the challenges of providing appropriate dementia care in rural areas. A community-based approach was used to obtain input from decision-makers and others to develop the objectives and design for a study of rural dementia care in the province of Saskatchewan, Canada. The resulting study design, which used both qualitative and quantitative methods, was then pilot tested in one rural health district (16,000 km2, population 20,000). This paper describes the study development process and reports selected findings from focus groups conducted with home care staff and family members, focussing on the theme of low use of formal supportive services such as home care and support groups by family caregivers. Participants identified eight barriers to the use of formal services, described consequences of low service use, and suggested strategies for addressing this concern.

Job strain among staff of rural nursing homes: A comparison of nurses, aides, and activity workers

Caring for growing numbers of residents with Alzheimer’s disease and related dementias increases the potential for stress among nursing home staff. To better understand occupational stress among caregivers in rural nursing homes, the authors studied differences in job strain among registered nurses, nursing aides, and activity workers. The authors discuss data from their survey questionnaires and focus group interviews with staff, providing insight into job strain and possible intervention strategies to improve the work environment.

Prevalence of antinuclear antibodies in a rural population.

Exposure to environmentally and occupationally encountered toxicants can be associated with the development of certain autoimmune diseases and with the induction of antinuclear antibodies (ANA). Some chemicals used in the agricultural industry are known to affect immune function but their roles in the induction of autoimmunity in general, and ANA in particular, have not been reported previously. This study was undertaken to establish the prevalence of ANA in a rural population and to determine environmental and occupational exposures with which they are associated. This cross-sectional study represented one component of an interdisciplinary project (Prairie Ecosystem Study [PECOS], Eco-Research Program, Tri-Council Secretariat of Canada) designed to explore, in a rural population, the roles of environmental exposures as determinants of human health status. Information regarding lifetime, current, and main occupational exposures in the rural-dwelling study population was derived from a self-administered questionnaire. Sera from consenting subjects, collected during the months of February and March 1996, were assayed for ANA by indirect immunofluorescence on HEp-2 cells. The study population comprised 322 adult subjects (mean age 49.3+/-14.7 yr; range 16-87 yr). Statistical analyses adjusted for age and sex revealed that the presence of ANA among the participants was associated with a current agricultural occupation that included oilseed production, hog production, or poultry production. There was a significant association between ANA positivity and a current main farming operation of crop production. There was also an association among individual participants between lifetime exposure to the insecticide class of pesticides and the presence of ANA. In this rural study population, ANA positivity was significantly associated with lifetime exposure specifically to carbamate, organochlorine (including aldrin, chlordane, dieldrin, endrin, heptachlor, and lindane, but excluding DDT and methoxychlor), and pyrethroid insecticides and to phenoxyacetic acid herbicides, including 2,4-D. After adjustment for age, sex, and other insecticide exposures, multivariate analyses indicated that ANA positivity was associated with current oilseed production and with lifetime exposure to pyrethroid insecticides. In a rural population, ANA were associated with production of certain crops and certain animals and exposure to specific pesticides. The data indicate that some occupational exposures related to the agricultural industry are associated with the presence of ANA, a serologic expression of autoimmunity.

Catechol-O-methyltransferase and catecholamines in anxiety and relaxation

Levels of anxiety, plasma epinephrine and norpinephrine, and red blood cell (RBC) catechol-O-methyltransferase (COMT) activity were measured before and after 4 weeks of relaxation training in a group of 15 drug-free, anxious subjects and at a similar interval in a group of 15 drug-free, healthy controls. The index group showed significant decreases in levels of anxiety and plasma epinephrine and norepinephrine after treatment. No changes were observed in the control values. RBC COMT did not show any significant differences in activity between the index and control groups and between the pre- and posttreatment values. Similarly, COMT activity levels failed to correlate with levels of anxiety and catecholamines before or after treatment. These findings indicate that anxiety is unlikely to have an effect on RBC COMT activity, whereas it has a direct effect on plasma catecholamines.

Health and environment of rural families: results of a Community Canvass survey in the Prairie Ecosystem Study (PECOS).

This cross-sectional survey was conducted as Phase I of the Prairie Ecosystem Study (PECOS): Environmental Pesticide Exposure and Human Health. In November of 1995, community volunteers delivered a self-administered household questionnaire to 1185 rural households in southern Saskatchewan, Canada. The survey provided a broad description of the general health and the physical environment of 511 men, 499 women, and 393 children (< 18 years of age) residing in 549 respondent households in the rural study area (population density of about one person/km2). Families in the respondent households resided on a farm, in town or both. Of the 369 households that operated a farm, 25.2% of the households did not list the farm as their primary household. Residents of both farming and non-farming households reported contact with pesticides and fertilizers through home or garden use. History of smoking was greater among men and women from non-farming households. The most commonly reported health problems among the children were a history of bronchitis, asthma, skin allergies, pneumonia, and hay fever. The most frequently reported health problems among the men were a history of high blood pressure, bronchitis, pneumonia, hearing problems, and stress; and among the women were a history of bronchitis, high blood pressure, shortness of breath, and pneumonia. Compared to farming households, more members of non-farming households reported a history of respiratory problems, particularly bronchitis among the women and children. Overall, there were important differences in the smoking history, the occupational use of pesticides and fertilizers, and the general health status between the farming and non-farming households and individuals in this rural population.

Factors Associated with Detection of Bromoxynil in a Sample of Rural Residents

In regions of intensive crop production residents may be exposed to herbicides through direct contact or environmental sources. The environmental herbicide exposures of rural populations and resultant potential health effects are not well understood. Epidemiologic studies of herbicides have focused on occupational exposures using, primarily, self-reported data (e.g., information on occupational and nonoccupational herbicide use, agricultural practices and exposures, farm residence). Herbicide exposure characterization in epidemiologic research would be strengthened by the use of self-reported data and biological monitoring (e.g., measuring the herbicide parent compound or its metabolites in blood or urine specimens) to classify individual exposures, identify factors associated with exposure, and obtain integrated estimates of exposure. As both exposure metrics are susceptible to measurement error and some self-reported and biological monitoring data might not be correlated, a worthwhile first step is to identify self-reported data that are statistically associated with biological measures of exposure. This study used gas chromatography/mass spectrometry analysis to measure blood plasma concentrations of target herbicides in a sample of rural residents (men, women, and youths) of Saskatchewan, Canada, and identified factors, based on self-reported data, associated with detection. The questionnaire data and blood specimens were collected in February/March 1996 during winter (frozen soil and water and snow cover) conditions. Sixty-four of the 332 study participants (19.3%) had detectable levels of the herbicide bromoxynil although herbicide application in the region had not occurred for approximately 5mo and bromoxynil has a relatively short environmental half-life. The prevalence of detection of other target herbicides (2,4-D, triallate, trifluralin, dicamba, fenoxaprop, MCPA, and ethalfluralin) varied from 0.3% to 2.7%. Self-reported factors identified in the multiple-variable analysis as statistically significant predictors of bromoxynil detection included recent exposure to grain production as the main farming operation (statistically significant for producers and for nonfarming family members of producers), a history of bromoxynil use, a history of having felt ill with a pesticide exposure, and a history of a pesticide spill on skin or clothing, with apparent gender differences in the relative importance of these factors. Detection of bromoxynil in this rural sample, 3-4mo after freeze-up and winter snow cover, suggests either that bromoxynil is very slowly metabolized/excreted from the body or study participants were environmentally or occupationally exposed to the herbicide during this period. Further research is needed to elucidate the pathways of exposure, biological half-life, and potential human health effects of bromoxynil.

Reliability of environmental and occupational exposure data provided by surrogate respondents in a case-control study of Parkinson's disease

This study used data provided by 40 non-demented Parkinsons disease patients and 101 community controls, and by their 110 spouses and 31 adult children to assess the reliability of surrogate-provided rural environmental and occupational exposure information on the index subjects. The level of overall raw agreement between the index subjects and the spouse or adult child surrogates varied from 50.0 to 100.0% for the case-surrogate group and from 80.6 to 96.0% for the control-surrogate group. We did not detect significant differences in overall raw agreement between the case-surrogate and control-surrogate groups or between the spouse-surrogate and adult child-surrogate groups, for any of the variables studied. Considering all index subjects and their surrogates, the level of overall raw agreement was 80.3% for well water consumption, 82.3% for farm living, 85.8% for agricultural work, 87.1% for use of pesticides, 87.9% for field crop farming and 91.9% for use of fertilizers. However, the kappa estimates were lower, varying from 0.48 (SE = 0.20) for fertilizer use to 0.66 (SE = 0.11) for crop farming. The level of specific agreement was 52.2% for fertilizer use, 64.0% for pesticide use, 71.4% for agricultural work, 73.9% for crop farming, 80.9% for farm living, and 83.6% for well water consumption. The overall findings of this study support the use, if necessary, of spouses and adult children of index subjects as surrogate respondents in case-control studies of rural environment and occupational exposures and Parkinsons disease and, possibly, other neurologic diseases. Specific agreement seems to be a better index of reliability than overall agreement in studies where exposure is rare.

The Physical and Social Environments of Small Rural Nursing Homes: Assessing Supportiveness for Residents with Dementia

The physical and social environments are recognized as important therapeutic tools in the care of nursing home residents with dementia, yet little is known about the environments of rural nursing homes. This study was conducted in one rural health authority (16,000 km 2) in the province of Saskatchewan. Long-term institutional care was provided in seven small (15 to 35 beds), publicly funded nursing homes, none of which had separate dementia special care units (SCUs). The Physical Environmental Assessment Protocol (PEAP) was used to evaluate the facilities on nine key dimensions of dementia care environments. Facilities were most supportive in provision of privacy and least supportive on maximizing awareness and orientation . Focus groups were conducted with registered nurses, nursing aides, and activity workers. Staff caregivers identified six special needs of residents with dementia that were difficult to meet in the nursing homes, two of which were related to the physical environment (safety and a calm, quiet environment) and four of which were related to the social environment (meaningful activity and one-to-one contact, opportunity to use remaining abilities, flexible policy, and knowledgeable caregivers who enjoy working with persons with dementia). Staff suggested separate dementia SCUs as one approach to managing dementia care but also identified challenges in creating dementia units in small rural facilities. Results provide support for conceptual models of dementia care settings that emphasize the interaction of organizational, social, and physical factors.