Assessing pesticide safety knowledge among Hispanic migrant farmworkers in Oregon.

The purpose of this article is to report on the development and initial use of a pesticide knowledge test (PKT) specifically designed to evaluate agricultural workers' knowledge of the content mandated by the federal Worker Protection Standard (WPS). The PKT is a 20-item, true-false test, used in a sample of 414 adult and adolescent migrant farmworkers in Oregon. The overall mean score, i.e., number correct, was 15.67(78.4%), with both adults and adolescents demonstrating the most difficulty with questions related to the overall health effects of pesticides. The internal consistency was 0.73, when estimated using a method to correct for small sample sizes. Only six items had less than 70% correct answers. Content validity was achieved by basing the items directly on the Worker Protection Standard; face validity was obtained by having the final version of the test reviewed by a bilingual (English-Spanish) educator familiar with the requirements of the WPS. Overall, adult participants scored better than adolescents, and those with previous pesticide training scored better than those without. There were no differences in scores based on gender or whether the test was taken in English or Spanish; however, participants who spoke indigenous languages scored significantly lower than those who did not. These results indicate that the PKT is a valid, reliable measure of worker knowledge of the content of the WPS, although it does not measure the extent to which that knowledge is actually used in the work setting.

Pesticide knowledge and risk perception among adolescent Latino farmworkers.

A substantial proportion of the agricultural production in the U.S. is dependent on the labor of Latino farmworkers. While exact figures are not known, it is estimated that adolescents make up 7% of this valuable workforce. These young workers may be at increased risk for the toxic effects of environmental exposures encountered during their work. Furthermore, language barriers and health beliefs may influence the risk perceptions of this population. We conducted a cross-sectional survey of migrant adolescent farmworkers in 1998 to investigate their work practices, health beliefs, and pesticide knowledge. The large majority of the adolescents in our sample were from Mexico, and 36.3% spoke primarily indigenous languages. Many of the adolescents (64.7%) were traveling and working in the U.S. independent of their parents. Few of the adolescents reported having received pesticide training; however, 21.6% of the sample reported that their current work involved mixing and/or applying agricultural chemicals. The scores on the pesticide knowledge questionnaire were found to significantly predict self-reported use of protection for adolescent farmworkers. The results of this study point to a need for improved pesticide training in youth agricultural workers and specialized education efforts directed toward minorities who speak indigenous dialects. Special attention is merited toward adolescent farmworkers who report that their work includes mixing or applying agricultural chemicals. As the number of adolescent farmworkers increases in the U.S. and the characteristics of the migrant stream continue to change, culturally and developmentally appropriate instruments are needed to adequately assess the health beliefs and protective practices of this population.

Work characteristics and pesticide exposures among migrant agricultural families: a community-based research approach.

There are few data on pesticide exposures of migrant Latino farmworker children, and access to this vulnerable population is often difficult. In this paper we describe a community-based approach to implement culturally appropriate research methods with a migrant Latino farmworker community in Oregon. Assessments were conducted in 96 farmworker homes and 24 grower homes in two agricultural communities in Oregon. Measurements included surveys of pesticide use and work protection practices and analyses of home-dust samples for pesticide residues of major organophosphates used in area crops. Results indicate that migrant farmworker housing is diverse, and the amounts and types of pesticide residues found in homes differ. Azinphos-methyl (AZM) was the pesticide residue found most often in both farmworker and grower homes. The median level of AZM in farmworker homes was 1.45 ppm compared to 1.64 ppm in the entry area of grower homes. The median level of AZM in the play areas of grower homes was 0.71 ppm. The levels of AZM in migrant farmworker homes were most associated with the distance from fields and the number of agricultural workers in the home. Although the levels of AZM in growers and farmworker homes were comparable in certain areas, potential for disproportionate exposures occur in areas of the homes where children are most likely to play. The relationship between home resident density, levels of pesticide residues, and play behaviors of children merit further attention.

The Oregon migrant farmworker community: an evolving model for participatory research.

Migrant farmworker communities present distinct challenges that require new approaches for community participation in research. In the State of Oregon an agency that advocates for the migrant farmworker community has collaborated successfully with university researchers to implement a research program directed to reducing pesticide exposures among the children of migrant farmworkers. The research process has included both qualitative research methods with members of the community and quantitative approaches to measure pesticide dust residues in homes, biomarkers of pesticide exposure, and effects on health. A committee of university and community stakeholders advises the research. Evaluative processes have been initiated to assess the effectiveness of the participatory model used in this project. The components of the preliminary process evaluation and results are presented. Evaluative data show that researchers and community members differ on perceptions of community involvement and the extent to which communication problems have been resolved between the two groups. Suggestions for improved community involvement and communication are given.

Monitoring acetylcholinesterase levels in migrant agricultural workers and their children using a portable test kit.

The EQM Research, Inc., portable test kit was evaluated as a surveillance tool for blood cholinesterase levels among migrant workers and their children. Laboratory validation demonstrated a linear relationship between the reference Ellman and kit methods (Ellman = 0.95 x kit result + 0.82, r2 = 0.98). Pre- and post-season cholinesterase levels measured in 70 farm workers were within normal ranges, but significantly different at 28.5 and 29.7 U/g Hb, respectively (paired t-test, p = 0.014). Results from 98 migrant farm worker children and a comparison group of 53 age-matched non-agricultural children showed that cholinesterase levels were not significantly different between the agricultural and non-agricultural children (ANOVA, p = 0.69). These data demonstrate that a portable test kit can provide useful data pesticide exposures when measurements are made in a temperature-controlled setting.

Symptoms of Gulf War veterans possibly exposed to organophosphate chemical warfare agents at Khamisiyah, Iraq.

During the 1991 Gulf War, some Allied troops were potentially exposed to sarin/cyclosarin as the result of the destruction of Iraqi munitions at Khamisiyah. To evaluate the prevalence of past and current symptoms known to be associated with exposure to these chemical warfare agents, the authors conducted a computer-assisted telephone survey of 2,918 U.S. Gulf War veterans. Veterans who had participated in or witnessed the demolition in 1991 were more likely to report historical or extant symptoms than were veterans from other military units. These results should be viewed cautiously because they are based on symptoms recalled nine years after the event without precise characterization of exposure. Nonetheless, the findings suggest that symptoms consistent with low-level sarin exposure may have initially occurred, and health effects may have persisted in the veterans who were nearest to the demolition activity. Further research is warranted.

Symptom factor analysis, clinical findings, and functional status in a population-based case control study of Gulf War unexplained illness.

Few epidemiological studies have been conducted that have incorporated clinical evaluations of Gulf War veterans with unexplained health symptoms and healthy controls. We conducted a mail survey of 2022 Gulf War veterans residing in the northwest United States and clinical examinations on a subset of 443 responders who seemed to have unexplained health symptoms or were healthy. Few clinical differences were found between cases and controls. The most frequent unexplained symptoms were cognitive/psychological, but significant overlap existed with musculoskeletal and fatigue symptoms. Over half of the veterans with unexplained musculoskeletal pain met the criteria for fibromyalgia, and a significant portion of the veterans with unexplained fatigue met the criteria for chronic fatigue syndrome. Similarities were found in the clinical interpretation of unexplained illness in this population and statistical factor analysis performed by this study group and others.

Self-reported exposures and their association with unexplained illness in a population-based case-control study of Gulf War veterans.

Many factors have been considered as possible causes of the unexplained illness reported by veterans of the Gulf War (GW). In this study, we report an analysis of risk factors and unexplained illness in a population-based sample of GW veterans who underwent clinical evaluation. Multiple risk factors were compared in 241 veterans who met criteria for unexplained illness and 113 healthy controls. Results suggest that GW unexplained illness is most highly associated with combat conditions, heat stress, and having sought medical attention during the GW. When controlling for multiple simultaneous exposures during the GW, interactions around pyridostigmine bromide, insecticides and repellents, and stress were not significant. These results indicate that most unexplained illness in GW veterans cannot be explained by neurotoxic effects of exposures to chemicals that inhibit cholinesterase activity.

Strategies to assess validity of self-reported exposures during the Persian Gulf War. Portland Environmental Hazards Research Center.

Research in the area of Persian Gulf War Unexplained Illnesses (PGWUI) is heavily dependent on self-reports of exposures. The Portland Environmental Hazards Research Center (PEHRC) conducted a population-based case-control study utilizing techniques to measure the magnitude of potential error in self-reports of exposure. While it is impossible to verify most exposures in the Persian Gulf War (PGW), results of our study reveal significant overreporting of exposures that can be verified based on the time period served in the Persian Gulf. Test-retest reliability estimates indicate inconsistency in frequency and rate of self-reported exposures during the PGW. Unexplained illness in PGW veterans has received much political and scientific attention. Self-reported exposures in surveys returned preceding and following media reports on particular exposure such as nerve gas or pesticides are presented. These results are useful in the interpretation of findings related to the PGWUI and in the design of future investigations.

Gulf War unexplained illnesses: persistence and unexplained nature of self-reported symptoms.

Most published reports of health symptoms among Gulf War (GW) veterans have been based on self-reported questionnaire data. The presence of these symptoms at the time of a clinical evaluation and the unexplained nature of the symptoms have not been described. We report the findings of a sample of symptomatic veterans that were examined as part of a population-based case-control study of GW unexplained illnesses. Participants in the case-control study were selected from responders to a cross-sectional survey of a random sample of GW veterans residing in the northwestern United States. The initial survey questionnaire solicited information on the presence of fatigue and psychological/cognitive, gastrointestinal, musculoskeletal, and dermatological problems. The persistence of the symptoms and possible explanatory diagnoses were explored at the time of the clinical evaluation. Findings from the first 225 participants who completed clinical examinations indicate significant differences between self-reported symptoms on the survey questionnaire and those confirmed at the time of clinical exam. The agreement between symptoms reported both on the survey and at the time of examination varies across the symptom groups. While self-reported unexplained fatigue was confirmed at the time of clinical encounter in 79% of participants, self-reported gastrointestinal symptoms were confirmed at the clinical encounter in only 20% of participants. Differences between symptoms reported on the survey questionnaire and those confirmed at the time of clinical encounter were attributable to finding a clinical diagnosis for the symptom, resolution of symptom(s) between time of questionnaire and clinical exam, and inadvertent endorsement of the symptom on the questionnaire. These findings suggest that due to the possibility of outcome misclassification, inappropriate conclusions may be drawn about the association between exposures and unexplained illnesses in GW veterans from data derived solely from self-administered questionnaires.

Chemical mixtures in the workplace. Research and practice.

1. Exposures to mixtures of chemicals in occupational settings and in the environment are of increasing concern. No single approach is appropriate for determining the risk associated with exposure to chemical mixtures. 2. The effects of coexposure of chemicals can occur in different stages of metabolism, including uptake, elimination, biotransformation, and binding. 3. Solvents represent the most widespread use of multicomponent mixtures in industry today. Solvents have the ability to inhibit the metabolism of other chemicals. 4. Lifestyle factors such as exercise, alcohol use, smoking, and the use of medications can affect the uptake and metabolism of chemicals. The effects of these factors are of particular significance in interpreting the results of biological monitoring of exposed workers.

U.S. Gulf War Veterans: service periods in theater, differential exposures, and persistent unexplained illness. Portland Environmental Hazards Research Centre.

Approximately 80,000 of the 697,000 American men and women who were stationed in SW Asia during the Gulf War (GW) report unexplained illness consisting of symptoms of persistent fatigue, cognitive difficulties, such as mild memory loss, diffuse muscle and joint pain, gastrointestinal symptoms, skin lesions, and respiratory problems, among others. Associations between major symptom groups and periods of deployment in the theater of operations have been sought in a population-based, clinical case-control study of GW veterans resident in the north-western region of the United States. No statistically significant differences were evident in the proportion of cases with unexplained fatigue, cognitive/psychological or musculoskeletal symptoms among veterans present in SW Asia in 3 specific time periods: (a) 8/1/1990-12/31/1990 (which includes Desert Shield), (b) the period surrounding Desert Storm (1/1/1991-3/31/1991), and (c) the (post-combat) period immediately following hostilities (4/1/1991-7/31/1991). There was a trend for all 3 case symptoms to be more common among GW veterans who served in the post-combat period. As numbers in these deployment groups were small, and power to detect differences low, the apparent absence of significant differences in the frequency of major symptom groups among these veterans requires confirmation in a larger study. Deployment for discrete periods in SW Asia is a method to separate distinct constellations of environmental factors; these are useful for analyses of associations among symptoms and exposures given the near-total absence of objective data on chemical and other possible exposures in the theater of operations.

Reproductive hazards: an overview of exposures to health care workers.

1. Anesthetic gases, particularly nitrous oxide, have been investigated for potential reproductive, mutagenic, and carcinogenic effects. Waste gases have been found in high concentrations, even with work settings with scavenger systems in place. 2. Antineoplastic drugs, commonly used to treat persons with cancer, are virtually all considered to be embryo-fetal toxic. OSHA has issued comprehensive guidelines covering staff training, handling practices, and use of protective equipment. 3. The toxic effect of non-ionizing radiation has been a frequent topic of public and scientific debate. At this time no evidence exists of a reproductive hazard to health care workers. 4. Biologic agents such as rubella, hepatitis, cytomegalovirus, varicella, and human immunodeficiency virus frequently have the potential for adverse effects on the fetus. Administration of a vaccine or care of patients with active infection may be contraindicated in pregnancy.

Studies on the distribution of cholesterol, phospholipid, and protein in the human and bovine lens.

The regional distribution of cholesterol, phospholipid and protein content was determined on pools of human lenses ranging from 13 to 68 years old. The study was undertaken to establish age matched controls for comparison with cataractous lenses. Future spectroscopic structure analysis of human lenses will be performed and the results related to chemical composition. The molar cholesterol to phospholipid ratio was 3.5 +/- 0.3 for human lens. This ratio is high for human tissue. The lens ratio increased from 2.2 +/- 0.3 in the equatorial region to 9.2 +/- 1.6 in the nuclear region. This trend was also observed in the bovine lens. The relative amount of protein increased concomitantly from 0.13 +/- 0.02 Kg protein per gram lipid in the equatorial region to 0.33 +/- 0.06 in the nucleus. The cholesterol to protein ratio remained constant throughout the lens at 0.073 +/- 0.003 Kg suggesting cholesterol could be associated with the crystallin proteins. In partially purified membrane preparations the cholesterol to phospholipid molar ratio was 2.6 +/- 0.2 and 3.2 +/- 0.2 for the cortex and nucleus respectively, three times lower than for the whole tissue. The high cholesterol content could account for the observed rigidity of membranes measured by infrared spectroscopic examination of the CH stretching band.