Tamara E. Hennessy-Burt

Engaging a Hard-to-Reach Population in Research: Sampling and Recruitment of Hired Farm Workers in the MICASA Study

Hired farm workers provide the majority of the workforce for Californias labor-intensive agricultural sector Agriculture is one of the most hazardous occupations, but there has been little research into the etiology of poor health outcomes that occur disproportionately in hired farm worker populations. MICASA is a cohort investigation of occupational and environmental health risks in hired farm worker households in Mendota, California, that employed a two-stage sampling process, including random selection of census blocks and door-to-door enumeration. The aim of this analysis was to evaluate the success of the sampling process and compare demographics of the enumerated population to other regional samples of Latino populations. In the enumeration, 1257 addresses were mapped and 729 hired farm worker households were enumerated. Findings showed no significant differences between the enumerated population and the resulting MICASA study sample; however, the MICASA population was more likely to be male, from Central America, work in agriculture, and have fewer years residency in the U.S. than California Health Interview Survey (CHIS) respondents. Additionally, 9.4% of the enumerated dwellings were back houses or unofficial dwellings and may have been missed by the U.S. Census 2000. Demographic comparisons between the enumerated population, census data, and CHIS data highlight the differences in these sampling methods and suggest possible demographic changes in hired farm workers in California. While difficulties in accessing hired farm workers often account for the lack of population-based research, the MICASA cohort provides an opportunity to examine occupational health patterns relevant to other farm worker populations.

Pyrethroids in house dust from the homes of farm worker families in the MICASA study.

Indoor pesticide exposure is a growing concern, particularly for pyrethroids, a commonly used class of pesticides. Pyrethroid concentrations may be especially high in homes of immigrant farm worker families, who often live in close proximity to agricultural fields and are faced with poor housing conditions, potentially causing high pest infestation and pesticide use. We investigate levels of pyrethroids in the house dust of farm worker family homes in a study of mothers and children living in Mendota, CA, within the population-based Mexican Immigration to California: Agricultural Safety and Acculturation (MICASA) Study. We present pesticide use data and levels of pyrethroid pesticides in indoor dust collected in 2009 as measured by questionnaires and a GC/MS analysis of the pyrethroids cis- and trans-permethrin, cypermethrin, deltamethrin, esfenvalerate and resmethrin in single dust samples collected from 55 households. Cis- and trans-permethrin had the highest detection frequencies at 67%, with median concentrations of 244 and 172ng/g dust, respectively. Cypermethrin was detected in 52% of the homes and had a median concentration of 186ng/g dust. Esfenvalerate, resmethrin and deltamethrin were detected in less than half the samples. We compared the pyrethroid concentrations found in our study to other studies looking at both rural and urban homes and daycares. Lower detection frequencies and/or lower median concentrations of cis- and trans-permethrin and cypermethrin were observed in our study as compared to those studies. However, deltamethrin, esfenvalerate and resmethrin were detected more frequently in the house dust from our study than in the other studies. Because households whose children had higher urinary pyrethroid metabolite levels were more likely to be analyzed in this study, a positive bias in our estimates of household pyrethroid levels may be expected. A positive association was observed with reported outdoor pesticide use and cypermethrin levels found in the indoor dust samples (rs=0.28, p=0.0450). There was also a positive association seen with summed pyrethroid levels in house dust and the results of a pesticide inventory conducted by field staff (rs=0.32, p=0.018), a potentially useful predictor of pesticide exposure in farm worker family homes. Further research is warranted to fully investigate the utility of such a measure.

Acculturation-Related Predictors of Very Light Smoking Among Latinos in California and Nationwide

The prevalence of light smoking has increased among Latinos. The purpose of this study was to identify demographic and acculturation-related factors associated with very light smoking, defined as smoking 1–5 cigarettes per day (CPD), among Latinos in California and nationwide. Latino smokers in the 2007–2008 National Health and Nutrition Examination Survey (NHANES) or the 2009 California Health Interview Survey (CHIS) were analyzed. Logistic regression assessed factors associated with very light smoking. Among NHANES smokers, those born in Mexico or who lived fewer years in the US were more likely to be very light smokers than 6+ CPD smokers. Among CHIS smokers, those born in Mexico, in another Spanish speaking country, or who spent smaller percentages of their life in the US were more likely to be very light smokers. Findings from this study can be used to design tobacco control media campaigns that include very light smokers.

Agricultural Injury in California Hispanic Farm Workers: MICASA Follow-up Survey

ABSTRACT The authors report here results from the first follow-up survey of the Mexican Immigration to California: Agricultural Safety and Acculturation (MICASA) cohort of community-dwelling immigrant Hispanic farm workers in Californias Central Valley. Among 560 participants the authors observed cumulative 1-year injury incidence of 6.6% (all injuries) and 4.3% (agricultural injuries). Increased prospective injury risk was associated with males, US birth, years lived in the United States, family income, and poor self-rated health. Agricultural injuries were associated most frequently with being struck by an object, falls, and cutting instruments, whereas over two thirds of nonagricultural injuries involved motor vehicles. Prevention should focus on safe handling of tools and materials, falls, and motor vehicle safety.