The Community Participatory Approach to Measuring Farmworker Pesticide Exposure (PACE3) study is a prospective, workforce-based research study designed to assess the health of Latino farmworkers and their families in eastern North Carolina.12
The study design and methods have been described previously.12;13
Briefly, PACE3 was a longitudinal study of a fixed cohort; the initial survey of the population began in June 2007 when 287 farmworkers were recruited from 44 farmworker camps in 11 eastern North Carolina counties. In June 2008, follow-up of the cohort began with a target of recruiting 120 members of the original population to participate in additional data collection. The follow-up was proposed a pilot study to assess the feasibility of collecting additional data, including a questionnaire designed to assess respiratory health. The recruitment goal was to have at least 100 participants complete all three rounds of data collection, therefore 120 participants were recruited in order to account for expected loss to follow-up. Farmworker camps were visited by study personnel in random order and the target sample size was reached after 29 camps were recruited.13
Wake Forest University School of Medicine Institutional Review Board approved the study protocol and instruments, and each participant provided written informed consent.
A total of 122 participants were enrolled and completed respiratory health questionnaires administered during three rounds of data collection during the summer of 2008. Dates of data collection were categorized into three approximately month-long time intervals: (1) June 13-July 11 (n=122), (2) July 12-August 10 (n=117), and (3) August 11-September 9 (n=114). Three participants were lost to follow-up before July 12th and five others were lost before August 11th. The final study population in this analysis is the 122 farmworkers who participated in the first round of data collection in 2008.
Questionnaires were administered by Spanish-speaking study personnel who traveled to the farmworkers’ residences for each round of data collection. Demographic and other characteristics of the population were collected in the first questionnaire administered. In the occupational exposure assessment portion of all three questionnaires, participants responded to questions about whether they worked on each of the last three days, including today, and then indicated how many hours they spent performing selected activities (e.g., planting, applying pesticide, harvesting) on each of the last three days. Respondents who indicated that they performed the activities one or more hours on any of the last three days were classified as having performed the specific activity.
Respiratory and allergic symptoms were identified using symptom-related questions based on items from the European Community Respiratory Health Survey questionnaire.14
In all three rounds of data collection, respondents were also asked whether they had wheezing or difficulty breathing, itchy eyes, nasal allergies, or runny nose in the last three days. In the initial questionnaire, respondents were asked whether they ever experienced wheezing symptoms and whether they had wheezing, been awoken by shortness of breath, or had nasal allergies in the last 12 months. In the next two questionnaires, these items referred to the last month, referencing the month since the previous data collection.
There are two levels of clustering in these data: repeated measures of the same individual and clustering of farmworkers within farmworker camps. To account for this data structure, we estimated associations between occupational activities and respiratory symptoms using alternating logistic regression to compare the odds of symptoms among farmworkers with each work activity exposure to those of farmworkers without the exposure.15;16
Models were adjusted for age, included as a continuous variable, and smoking status (current smoker, former smoker, lifetime non-smoker). We performed all analyses using SAS version 9.2 (SAS Institute Inc., Cary, NC).