Dynamics of Docosahexaenoic Acid Utilization by Mouse Peritoneal Macrophages.

In this work, the incorporation of docosahexaenoic acid (DHA) in mouse resident peritoneal macrophages and its redistribution within the various phospholipid classes were investigated. Choline glycerophospholipids (PC) behaved as the major initial acceptors of DHA. Prolonged incubation with the fatty acid resulted in the transfer of DHA from PC to ethanolamine glycerophospholipids (PE), reflecting phospholipid remodeling. This process resulted in the cells containing similar amounts of DHA in PC and PE in the resting state. Mass spectrometry-based lipidomic analyses of phospholipid molecular species indicated a marked abundance of DHA in ether phospholipids. Stimulation of the macrophages with yeast-derived zymosan resulted in significant decreases in the levels of all DHA-containing PC and PI species; however, no PE or PS molecular species were found to decrease. In contrast, the levels of an unusual DHA-containing species, namely PI(20:4/22:6), which was barely present in resting cells, were found to markedly increase under zymosan stimulation. The levels of this phospholipid also significantly increased when the calcium-ionophore A23187 or platelet-activating factor were used instead of zymosan to stimulate the macrophages. The study of the route involved in the synthesis of PI(20:4/22:6) suggested that this species is produced through deacylation/reacylation reactions. These results define the increases in PI(20:4/22:6) as a novel lipid metabolic marker of mouse macrophage activation, and provide novel information to understand the regulation of phospholipid fatty acid turnover in activated macrophages.

Phospholipid Arachidonic Acid Remodeling During Phagocytosis in Mouse Peritoneal Macrophages.

Macrophages contain large amounts of arachidonic acid (AA), which distributes differentially across membrane phospholipids. This is largely due to the action of coenzyme A-independent transacylase (CoA-IT), which transfers the AA primarily from diacyl choline-containing phospholipids to ethanolamine-containing phospholipids. In this work we have comparatively analyzed glycerophospholipid changes leading to AA mobilization in mouse peritoneal macrophages responding to either zymosan or serum-opsonized zymosan (OpZ). These two phagocytic stimuli promote the cytosolic phospholipase A2-dependent mobilization of AA by activating distinct surface receptors. Application of mass spectrometry-based lipid profiling to identify changes in AA-containing phospholipids during macrophage exposure to both stimuli revealed significant decreases in the levels of all major choline phospholipid molecular species and a major phosphatidylinositol species. Importantly, while no changes in ethanolamine phospholipid species were detected on stimulation with zymosan, significant decreases in these species were observed when OpZ was used. Analyses of CoA-IT-mediated AA remodeling revealed that the process occurred faster in the zymosan-stimulated cells compared with OpZ-stimulated cells. Pharmacological inhibition of CoA-IT strongly blunted AA release in response to zymosan but had only a moderate effect on the OpZ-mediated response. These results suggest a hitherto undescribed receptor-dependent role for CoA-independent AA remodeling reactions in modulating the eicosanoid biosynthetic response of macrophages. Our data help define novel targets within the AA remodeling pathway with potential use to control lipid mediator formation.

The Contribution of Cytosolic Group IVA and Calcium-Independent Group VIA Phospholipase A2s to Adrenic Acid Mobilization in Murine Macrophages.

Adrenic acid (AA), the 2-carbon elongation product of arachidonic acid, is present at significant levels in membrane phospholipids of mouse peritoneal macrophages. Despite its abundance and structural similarity to arachidonic acid, very little is known about the molecular mechanisms governing adrenic acid mobilization in cells of the innate immune system. This contrasts with the wide availability of data on arachidonic acid mobilization. In this work, we used mass-spectrometry-based lipidomic procedures to define the profiles of macrophage phospholipids that contain adrenic acid and their behavior during receptor activation. We identified the phospholipid sources from which adrenic acid is mobilized, and compared the data with arachidonic acid mobilization. Taking advantage of the use of selective inhibitors, we also showed that cytosolic group IVA phospholipase A2 is involved in the release of both adrenic and arachidonic acids. Importantly, calcium independent group VIA phospholipase A2 spared arachidonate-containing phospholipids and hydrolyzed only those that contain adrenic acid. These results identify separate mechanisms for regulating the utilization of adrenic and arachidonic acids, and suggest that the two fatty acids may serve non-redundant functions in cells.

Short- and medium-term effect of kinesio taping or electrical stimulation in hemiplegic shoulder pain prevention: A randomized controlled pilot trial.

OBJECTIVE: To compare the short and medium-term effectiveness of combining Kinesio Tape (KT) or neuromuscular electrical stimulation (NMES) with a conventional approach to prevent shoulder pain after stroke. METHODS: Thirty-one first-time stroke survivors (58.06% females) were recruited and randomly assigned to one group; Control (n = 10), KT (n = 11), or NMES (n = 10). Ten of all participants were lost during follow-up because of death or a second stroke. The control group underwent conventional treatment (careful shoulder handling and daily mobilizations). This approach was combined with KT or NMES over deltoid muscles in the KT and NMES groups respectively. Measurements were taken at baseline, and at weeks 1, 2, 3, 4, 12, and 24 post-stroke. Data collected included self-perceived shoulder pain (Visual Analogue Scale), disability (Barthel Index and Berg scale), and upper limb function (Action Research Arm test). RESULTS: In all groups, shoulder pain did not appear during the first month (p < 0.001), but increased afterwards. In the between-groups analysis, all groups similarly improved disability and function, and no significant differences were observed for any measure (p > 0.05). CONCLUSION: The combination of KT or NMES with conventional treatment is no superior to conventional treatment alone to prevent hemiplegic shoulder pain.

Immediate changes in masticatory mechanosensitivity, mouth opening, and head posture after myofascial techniques in pain-free healthy participants: a randomized controlled trial.

OBJECTIVE: This study aimed to assess the immediate effects on masticatory muscle mechanosensitivity, maximal vertical mouth opening (VMO), and head posture in pain-free healthy participants after intervention with myofascial treatment in the temporalis and masseter muscles. METHODS: A randomized, double-blind study was conducted. The sample group included 48 participants (n=48), with a mean age of 21±2.47 years (18-29). Two subgroups were defined: an intervention group (n=24), who underwent a fascial induction protocol in the masseter and temporalis muscles, and a control group (n=24), who underwent a sham (placebo) intervention. The pressure pain threshold in 2 locations in the masseter (M1, M2) and temporalis (T1, T2) muscles, maximal VMO, and head posture, by means of the craniovertebral angle, were all measured. RESULTS: Significant improvements were observed in the intragroup comparison in the intervention group for the craniovertebral angle with the participant in seated (P<.001; F1,23=16.45, R2=0.41) and standing positions (P=.012, F1,23=7.49, R2=0.24) and for the pressure pain threshold in the masticatory muscles, except for M2 (P=.151; M1: P=.003; F1,23=11.34, R2=0.33; T1: P=.013, F1,23=7.25, R2=0.23; T2: P=.019, F1,23=6.41, R2=0.21). There were no intragroup differences for the VMO (P=.542). Nevertheless, no significant differences were observed in the intergroup analysis in any of the studied variables (P>.05). CONCLUSION: Myofascial induction techniques in the masseter and temporalis muscles show no significant differences in maximal VMO, in the mechanical sensitivity of the masticatory muscles, and in head posture in comparison with a placebo intervention in which the therapist's hands are placed in the temporomandibular joint region without exerting any therapeutic pressure.

Shoulder functionality after manual therapy in subjects with shoulder impingement syndrome: a case series.

The aim of the study was to identify the differences in functionality of the upper limb in subjects suffering from shoulder impingement syndrome after intervention by two manual therapy protocols. Randomized, single-blind study with a sample of 22 subjects (58 ± 10.86 years old) divided into two groups. The conventional-group (n = 11) received mobilizations of the shoulder and the experimental-group (n = 11) was treated with soft tissue techniques in the cervical and upper thoracic regions. These two groups received electrotherapy and postural advices. The treatment lasted three weeks (15 daily sessions of 1 h and 30 min). Both active and passive range of motion (ROM) and self-perceived functionality of the upper limb (DASH questionnaire) were measured. The experimental group showed a significant improvement in the DASH scores and both groups improved mobility in the intra-group comparison pre-intervention versus post-intervention (p < .05), but not statistically significant differences were found in the between-group comparison (p > .05). Our results suggest that a combined treatment with electrotherapy, postural hygiene and manual therapy, regardless of the protocol, improves shoulder mobility and functionality.

The Childhood Leukemia International Consortium.

BACKGROUND: Acute leukemia is the most common cancer in children under 15 years of age; 80% are acute lymphoblastic leukemia (ALL) and 17% are acute myeloid leukemia (AML). Childhood leukemia shows further diversity based on cytogenetic and molecular characteristics, which may relate to distinct etiologies. Case-control studies conducted worldwide, particularly of ALL, have collected a wealth of data on potential risk factors and in some studies, biospecimens. There is growing evidence for the role of infectious/immunologic factors, fetal growth, and several environmental factors in the etiology of childhood ALL. The risk of childhood leukemia, like other complex diseases, is likely to be influenced both by independent and interactive effects of genes and environmental exposures. While some studies have analyzed the role of genetic variants, few have been sufficiently powered to investigate gene-environment interactions. OBJECTIVES: The Childhood Leukemia International Consortium (CLIC) was established in 2007 to promote investigations of rarer exposures, gene-environment interactions and subtype-specific associations through the pooling of data from independent studies. METHODS: By September 2012, CLIC included 22 studies (recruitment period: 1962-present) from 12 countries, totaling approximately 31000 cases and 50000 controls. Of these, 19 case-control studies have collected detailed epidemiologic data, and DNA samples have been collected from children and child-parent trios in 15 and 13 of these studies, respectively. Two registry-based studies and one study comprising hospital records routinely obtained at birth and/or diagnosis have limited interview data or biospecimens. CONCLUSIONS: CLIC provides a unique opportunity to fill gaps in knowledge about the role of environmental and genetic risk factors, critical windows of exposure, the effects of gene-environment interactions and associations among specific leukemia subtypes in different ethnic groups.

Urban health inequities and the added pressure of climate change: an action-oriented research agenda.

Climate change will likely exacerbate already existing urban social inequities and health risks, thereby exacerbating existing urban health inequities. Cities in low- and middle-income countries are particularly vulnerable. Urbanization is both a cause of and potential solution to global climate change. Most population growth in the foreseeable future will occur in urban areas primarily in developing countries. How this growth is managed has enormous implications for climate change given the increasing concentration and magnitude of economic production in urban localities, as well as the higher consumption practices of urbanites, especially the middle classes, compared to rural populations. There is still much to learn about the extent to which climate change affects urban health equity and what can be done effectively in different socio-political and socio-economic contexts to improve the health of urban dwelling humans and the environment. But it is clear that equity-oriented climate change adaptation means attention to the social conditions in which urban populations live-this is not just a climate change policy issue, it requires inter-sectoral action. Policies and programs in urban planning and design, workplace health and safety, and urban agriculture can help mitigate further climate change and adapt to existing climate change. If done well, these will also be good for urban health equity.

Social conditions and urban health inequities: realities, challenges and opportunities to transform the urban landscape through research and action.

The process of urbanization entails social improvements with the consequential better quality-of-life for urban residents. However, in many low-income and some middle-income countries, urbanization conveys inequality and exclusion, creating cities and dwellings characterized by poverty, overcrowded conditions, poor housing, severe pollution, and absence of basic services such as water and sanitation. Slums in large cities often have an absence of schools, transportation, health centers, recreational facilities, and other such amenities. Additionally, the persistence of certain conditions, such as poverty, ethnic heterogeneity, and high population turnover, contributes to a lowered ability of individuals and communities to control crime, vandalism, and violence. The social vulnerability in health is not a "natural" or predefined condition but occurs because of the unequal social context that surrounds the daily life of the disadvantaged, and often, socially excluded groups. Social exclusion of individuals and groups is a major threat to development, whether to the community social cohesion and economic prosperity or to the individual self-realization through lack of recognition and acceptance, powerlessness, economic vulnerability, ill health, diminished life experiences, and limited life prospects. In contrast, social inclusion is seen to be vital to the material, psychosocial, and political aspects of empowerment that underpin social well-being and equitable health. Successful experiences of cooperation and networking between slum-based organizations, grassroots groups, local and international NGOs, and city government are important mechanisms that can be replicated in urban settings of different low- and middle-income countries. With increasing urbanization, it is imperative to design health programs for the urban poor that take full advantage of the social resources and resourcefulness of their own communities.

Condiciones de salud y trabajo en América Central / Work and health in Central America

En este trabajo se presentan las principales características de la población trabajadora centroamericana, así como losproblemas de salud y las políticas de protección y prevención existentes en la actualidad. Para ello, se revisaron documentosy fuentes específi cos de la Región. Se aporta información sobre las transiciones demográfi cas, la pobreza, la distribuciónde la población trabajadora por sectores y actividades económicas, la economía formal e informal, el desempleo, el trabajode la mujer y el trabajo infantil, entre otros temas. Se cuantifi ca los principales riesgos por sectores económicos. Se discutesobre los sistemas de aseguramiento de riesgos profesionales y los registros de exposiciones y efectos sobre la salud disponibles,así como sobre legislación y participación gremial y sindical. Los datos disponibles en materia de salud y trabajo son engeneral escasos, difi cultando la elaboración de políticas adecuadas y coherentes, su evaluación y el establecimiento de prioridades.La baja cobertura de seguros deja a una proporción importante de la población sin protección sanitaria. Se recomiendael desarrollo de sistemas de vigilancia adecuados (registros, encuestas periódicas, etc.) de las condiciones laboralesa nivel nacional y regional que permitan el establecimiento de estrategias de promoción de salud de las personas trabajadoras.También recomendamos el fortalecimiento de las políticas sociales y la divulgación de información sobre riesgos, efectosy legislación existente en la población trabajadora que favorezca la equidad social de la población para mejorar las condicionesde salud y trabajo de sectores menos favorecidos y del conjunto de trabajadores en general (AU)

We discuss the main characteristics of the working population, occupational health issues, and prevention and promotionpolicies in safety and health that currently exist in Central America. Available data and documentation on relatedtopics were reviewed. Demographic transitions, poverty, workforce distributions by sectors and economic activities, informaland formal work, unemployment, female and child labour are discussed, among other issues. Major occupational risks associated with selected economic sectors are presented. We also discuss insurance systems in relation to occupational riskregistries on exposures and health effects, legislation and union participation.Over all data on work and health-related conditions are scarce, limiting the development of accurate and coherent policies,their evaluation and defi nitions of occupational health-related priorities. Low level of insurance coverage results in ahigh proportion of the worker population without health care protection.We recommend the development or effective surveillance systems (registries, periodic surveys, etc.) that allow the monitoringof work and health conditions at the national and regional level and heand targeting of health promotion strategiesfor people at work. We also recommend the strengthening of public policies and the distribution of information regardingrisk factors, their adverse effects and existing legislation among the working population, in order to facilitate social equityand to improve work and health conditions of both disadvantaged sectors and the entire workforce(AU)

Causas y prevención del cáncer ocupacional: [revisión] / Causes and prevention of occupational cancer: [review]

Las neoplasias ocupacionales son altamente prevenibles. Esta comunicación resume los datos de los riesgos cancerígenos ocupacionales, destacando grupos importantes de trabajadores y la prevención. La Agencia Internacional para la Investigación del Cáncer, IARC, ha identificado en el Grupo 1, causa cáncer en humanos, 29 agentes que pueden presentarse en el lugar de trabajo, 26 en el Grupo 2 A, probablemente cancerígeno, y 113 en el Grupo 2B, posiblemente cancerígeno. Los agentes frecuentes en Centroamérica incluyen la radiación solar, Grupo 1, y la radiación ultravioleta, 2A, las emisiones diesel, 2A, los hidrocarburos poliaromáticos, 1-3, el humo de tabaco ambiental, 1, los compuestos de cromo hexavalente, 1, y el benceno, 1. En cuanto a los cánceres de mujeres, estudios de cáncer de mama y ovarios sugieren asociaciones con agentes ocupacionales. Los datos en la economía informal son pocos. Peligros cancerígenos para agricultores y peones agrícolas contemplan la exposición a radiación ultravioleta solar, virus, zoonosis, polvos, aflatoxinas, emisiones de diesel, solventes y plaguicidas. Agentes cancerígenos potenciales presentes en el Sector Salud incluyen: óxido de etileno, formaldehído, humo de tabaco ambiental, tricloroetileno, tetracloroetileno, benceno, asbesto, drogas, hormonas, antibióticos, plaguicidas, virus y desechos y gases cancerígenos. Algunas exposiciones durante el desarrollo y la infancia someten a los niños a riesgos cancerígenos. Prevenir los riesgos para la salud en el lugar de trabajo es responsabilidad del empleador. Se debe actuar con precaución en respuesta a la limitada evidencia plausible y creíble, sobre un peligro probable, y establecer comisiones mixtas de salud y seguridad en lugares de trabajo.

Occupational cancers are highly preventable. This communication summarizes the data on occupational carcinogenic hazards, highlighting important worker groups and prevention. The International Agency for Research on Cancer (IARC) has classified 29 agents that may occur atwork in Group 1 (carcinogenic in humans); 26 in Group 2A (probably carcinogenic); and 113 in Group 2B (possibly carcinogenic). Frequent occupational carcinogens in Central America include solar (Group 1) and ultraviolet (2A) radiation, diesel emissions (2A), polyaromatichydrocarbons (1-3), environmental tobacco smoke (1), hexavalent chromium compounds (1) andbenzene (1). Regarding women, studies on breast and ovarian cancer suggest associations with occupational exposures. The data on carcinogenic risks in the informal economy are scanty. Carcinogenic agents that may be present occur in agriculture include solar radiation, aflatoxins, diesel emissions, viruses, dusts, solvents and pesticides. Carcinogenic agents in the health sector include ethylene oxide; formaldehyde; environmental tobacco smoke; tri- and tetrachloroethylene; benzene; asbestos; carcinogenic drugs, hormones, antibiotics, pesticides, viruses and waste materials; and carcinogenic gases. Environmental exposures during development and infancy may cause childhood cancer. Prevention of health risks at the workplace is the responsibility ofthe employer. The principle of precaution, due to sparse, plausible and credible evidence about probable danger and the establishment of safety and health committees are recommended.

Parental occupational exposure to pesticides and the risk of childhood leukemia in Costa Rica.

OBJECTIVES: Parental exposure to pesticides and the risk of leukemia in offspring were examined in a population-based case-control study in Costa Rica. METHODS: All cases of childhood leukemia (N=334), in 1995-2000, were identified at the Cancer Registry and the Children's Hospital. Population controls (N=579) were drawn from the National Birth Registry. Interviews of parents were conducted using conventional and icon-based calendar forms. An exposure model was constructed for 25 pesticides in five time periods. RESULTS: Mothers' exposures to any pesticides during the year before conception and during the first and second trimesters were associated with the risk [odds ratio (OR) 2.4, 95% confidence interval (95% CI) 1.0-5.9; OR 22, 95% CI 2.8-171.5; OR 4.5, 95% CI 1.4-14.7, respectively] and during anytime (OR 2.2, 95% CI 1.0-4.8). An association was found for fathers' exposures to any pesticides during the second trimester (OR 1.5, 95% CI 1.0-2.3). An increased risk with respect to organophosphates was found for mothers during the first trimester (OR 3.5, 95% CI 1.0-12.2) and for fathers during the year before conception and the first trimester (OR 1.5, 95% CI 1.0-2.2 and OR 1.6, 95% CI 1.0-2.6, respectively), and benzimidazoles during the first, second, and third trimesters of pregnancy (OR 2.2, 95% CI 1.0-4.4; OR 2.2, 95% CI 1.0-5.0; OR 2.2, 95% CI 1.0-5.2, respectively). There was a suggestion of an exposure-response gradient for fathers as regards picloram, benomyl, and paraquat. Age at diagnosis was positively associated with fathers' exposures and inversely associated with mothers' exposures. CONCLUSIONS: The results suggest that parental exposure to certain pesticides may increase the risk of leukemia in offspring.

Funding of pilot projects in Latin America: a tool for capacity building in occupational health research.

There is a global need for trained researchers who can address the increasing burden of illness and injury and prepare future generations of researchers. Developing countries have a special need for practical, action-oriented interventions to address workplace problems, based on identification of needs and priorities, development of locally available solutions, and consideration of the sociopolitical context of work and how best to translate research findings into policies. Effective translation and application of research products from industrialized nations to developing countries is essential, but differences in the contexts and local realities of other nations limit extrapolating such research. Funding pilot research projects in developing countries is an effective, practical, and useful tool for training new investigators in research techniques and developing collaborative relationships among countries.

[Determining exposure history in occupational epidemiology]. / Determinación del historial de exposiciones en la epidemiolgía ocupacional.

In epidemiology, it is necessary that exposure indicators have good validity in order to obtain valid results when measuring the risks associated with occupational exposure to environmental noxious agents. However, ensuring the validity of past exposure data is no easy task. Because there are no environmental hygiene measures or representative levels of bioindicators signaling past exposure, self-reports have been used as a source of indirect exposure data. Unfortunately, data on specific agents are commonly poor and need to be complemented with data on the determinants of exposure. The validity of self-reports improves when certain techniques, such as control lists and icons, are employed, and the quality of individual exposure data improves when secondary data on exposure and its conditioning or determining factors are incorporated. Exposure can be determined by means of exposure matrices, assessment by experts, and exposure models, and by using a combination of primary and secondary data on exposure and its conditioning factors. Matrices contain pooled data and can thus lead to errors in classifying individual exposure and to biased risk estimates. Assessment by experts is probably the method with the highest validity, but it can become expensive when studies are large. It is also feasible to use a formal model for assessing perceivable exposures, complemented with expert assessments whenever the results of the model appear to deviate from reality.

Determinación del historial de exposiciones en la epidemiolgía ocupacional / Determining exposure history in occupational epidemiology

La validez de los indicadores de exposición es una condición necesaria en epidemiología si se han de obtener resultados válidos en la medición de los riesgos asociados con la exposición a agentes nocivos en el entorno laboral. Sin embargo, llevar a cabo la validación de estos indicadores de exposiciones pasadas no es tarea fácil. Debido a la falta de mediciones de referencia en el ámbito de la higiene industrial y de concentraciones representativas de bioindicadores que reflejen las exposiciones pasadas, el método de los autoinformes se ha utilizado para recoger datos de exposición indirectos. No obstante, los datos acerca de agentes nocivos específicos son a menudo deficientes y deben completarse con otros sobre los factores condicionantes de la exposición. La validez de los autoinformes mejora cuando se utilizan listas de verificación e iconos ilustrativos, mientras que la calidad de la información sobre las exposiciones personales mejora cuando se incorporan datos secundarios acerca de las exposiciones y de los factores que las condicionan o determinan. La exposición se puede determinar mediante matrices de exposición, evaluación por expertos y modelos de exposición, integrando datos primarios y secundarios acerca de las exposiciones y sus factores condicionantes. Las matrices contienen datos agrupados y, por consiguiente, pueden llevar a errores a la hora de clasificar las exposiciones individuales e introducir sesgos en la estimación de los riesgos. La evaluación por expertos es probablemente el método con el índice de validez más alto, pero puede entrañar costos muy altos en el caso de estudios de cierta magnitud. Otra posibilidad con buenas perspectivas es la de utilizar un modelo formal para evaluar las exposiciones patentes y mejorarlo mediante la evaluación por expertos en situaciones en las cuales los resultados del modelo parezcan alejarse de la realidad.

Assessment of pesticide exposure in the agricultural population of Costa Rica.

We describe a model for the retrospective assessment of parental exposure to 26 pesticides, selected by toxicity-based prioritization, in a population-based case-control study of childhood leukaemia in Costa Rica (301 cases, 582 controls). The model was applied to a subset of 227 parents who had been employed or self-employed in agriculture or livestock breeding. It combines external data on pesticide use for 14 crops, 21 calendar years and 14 regions, and individual interview data on determinants (task and technology, personal protective equipment, field reentry, storing of pesticides, personal hygiene) of exposure. Recall was enhanced by use of checklists of pesticides in the interview. An external database provided information on the application rate (proxy for intensity of potential exposure) for each pesticide. The calendar time was individually converted to five time windows (year before conception, first, second and third trimester, and first year of the child). Time-windowed individual data on determinants of exposure and their expert-based general weights and their category-specific hazard values jointly provided an individual determinant score. This score was multiplied by the application rate to obtain an individual index of exposure intensity during application. Finally, average exposure intensity during entire time windows was estimated by incorporating in the model the individual time fraction of exposure during application. Estimates of exposure intensities were proxies assumed to be proportional to dermal exposure intensity, which represents the major pathway of occupational exposure to pesticides. A simulated sensitivity analysis resulted in a correlation coefficient of 0.91 between two sets of 10 000 values of individual exposure indices, based on two different but realistic sets expert-assigned weights. Lack of measurement data on concurrent exposures in comparable circumstances precluded direct validation of the model.

Pesticide prioritization for a case-control study on childhood leukemia in Costa Rica: a simple stepwise approach.

Multiple exposures and rapidly changing use patterns are obstacles for adequate recall of pesticide exposures in epidemiologic studies. We present a simple stepwise approach for prioritization of pesticides as part of the exposure assessment strategy in an ongoing case-control study on pesticides and childhood leukemia in Costa Rica. Pesticide imports between 1977 and 2000, approximately the pertinent exposure period, were surrogates for use data. In the first phase, 323 active ingredients were identified, of which 219 were eliminated based on low usage and absence or negative results in a preliminary search in three major toxicity databases. In the second phase, the remaining 104 pesticides underwent scoring for their toxicodynamic potential (TDP) with regard to carcinogenicity, mutagenicity, and teratogenicity, weighted in this order. Bioavailability was assessed when TDP was multiplied by a weight for persistence and bioaccumulation, producing the intrinsic toxic potential (ITP). ITP was multiplied by an index of quantity (QI) of pesticide used in the exposure period, resulting in a weighted toxic potential (WTP). The top 25 positions in each of the four rankings (TDP, ITP, QI, and WTP) yielded together 64 highest-priority pesticides. This prioritization process has to be complemented with a further breakdown into crop-, time-, and biocide-specific shortlists to achieve a recall tool suitable for developing countries. Different parameters for prioritization assure inclusion of all relevant pesticides with regard to toxicity and bioavailability. The method contributes to cancer epidemiology in developing countries with access to basic use data and the Internet. The method is adaptable to other health outcomes.

An icon-based interview for the assessment of occupational pesticide exposure in a case-control study of childhood leukemia.

An icon-calendar interview form (ICF) for a case-control study of childhood leukemias and parental exposures to pesticides is described. It includes calendar sheets, icons for life events, crops, jobs, regions, non-agricultural jobs, application techniques and personal protection, markers for durations of exposure patterns, and checklists of pesticides. The ICF collects monthly data from two years before birth until diagnosis of cancer (index children) or until either the interview date or age 15 (controls). Data ascertainment was easy in 62% of interviews, moderately easy in 32%, and difficult in 6%. Seventy-eight subjects delivered data on specific pesticides with pesticide checklists, which improved identification of pesticides. ICF performs satisfactorily for crops, tasks, and other determinants of exposure. Data on pesticides will be further improved by introducing external data use on different crops, time periods, and regions, and by exposure modeling for 27 pesticides.