Audiometric findings of printing press workers exposed to noise and organic solvents.

OBJECTIVE: To determine if exposure to organic solvents and noise is associated with audiometric results among workers from a printing press in Mexico City. DESIGN: Cross-sectional study. STUDY SAMPLE: One hundred and seventy-six male workers at a printing press in Mexico City exposed to noise and organic solvents, including xylene, and 103 non-exposed male workers as reference group. Hearing thresholds were assessed with pure-tone audiometry. RESULTS: Poorer hearing thresholds were observed among printing workers than non-exposed controls, particularly among groups with over 5 years of exposure. Hearing thresholds differences were observed in the frequencies above 500 Hz, especially in 4000 Hz in all exposure groups compared to the reference. Adjusted models for age and previous exposure to noise and organic solvents showed worse hearing thresholds as years of seniority increased -ß coefficients (95% CI): ≤5 years: 3.06 dB (0.01, 6.10); >5-10 years: 4.51 dB (1.13, 7.89); >10 years: 4.58 dB (1.20, 7.96). Further analyses showed no interaction between noise and organic solvents on hearing thresholds, considering both current and previous occupational exposures. CONCLUSION: Exposure to noise levels that were below recommended exposure limits and organic solvents were associated with poorer hearing thresholds than those observed among non-exposed study participants. This suggests that workers exposed to solvents should be included in hearing conservation programmes, even when noise exposures are below 85 dB. If only noise levels were taken into consideration in the risk assessment of this worker population, the risk of hearing effects could have been overlooked.

Ototoxicity effects of low exposure to solvent mixture among paint manufacturing workers.

OBJECTIVE: To evaluate auditory function in a group of workers exposed to organic solvent mixture at a paint factory. DESIGN: Cross-sectional study. STUDY SAMPLE: One hundred and sixty-one workers were studied, 77 exposed to solvents and 84 unexposed. Fourteen solvents were measured, including toluene, xylene, and n-hexane. Pure-tone audiometry and brainstem auditory-evoked potentials (BAEP) were performed. Industrial noise was < 85 dBA and exposure levels to organic solvents were low. RESULTS: The exposed group showed a hearing impairment in both ears compared with the unexposed workers. Multiple linear regression models adjusted by age, chronic pathologies, and environmental noise for frequency means between 125 and 8000 Hz produced the following results: for the left ear, R(2) = 33.3%, exposed vs. unexposed ß = 4.1 (p < 0.001); and for the right ear, R(2) = 38%, exposed vs. unexposed ß = 4.8 (p < 0.001). Adjusted for age and chronic pathologies, waves III and V, and interpeak interval latencies were increased (p < 0.05) in both ears in the exposed group. CONCLUSIONS: Although solvent mixture concentrations and noise levels were low, our results demonstrate that there may be a concurrent ototoxicity and neurotoxicity condition and emphasize the importance of including BAEP analysis for comprehensive assessments. Future studies that include otoacoustic emissions assessments to monitor cochlear function and central auditory processing tests are imperative.

[Occupational exposure-associated hematological and immunologic manifestations to the benzene-toluene-xylene (Btx) mixture]. / Exposición ocupacional a mezcla de benceno-tolueno-xileno. Manifestaciones hematoinmunológicas.

Despite, the idea promoted to study occupational exposure to benzene and its mixture with toluene and xylene (BTX) because it appears to determine its toxicity and probably the production of additive effects, it persists interest to recognizing its hematological and immunotoxic effects. The fact that exposure to a sole substance in the occupational field is infrequent. Available contributions that analyze these implications are scarce, with contradictory results, and in their majority are limited to the fraction of benzene. Epidemiologic studies that have evaluated occupational exposure to any of the BTX fractions have been based on personal monitoring, while others have characterized this heterogeneously and are accompanied by weaker proposals. The conformation of specific methods to stimulate occupational exposure to the BTX mixture would contribute to its homogenization and allow for a more integral view in terms of determining BTX exposure. On the other hand, the application of BTX exposure biomarkers has been questioned in studies contemplating the specific biological effects of reference-associated chronic exposure. Analysis of the hematological and immunologic manifestations associated BTX mixture is based on information that is unclear, controversial, or even speculative to date.

[Update on epidemiology, pathophysiology, diagnosis and treatment of malignant pleural mesothelioma]. / Actualización sobre la epidemiología, fisiopatología, diagnóstico y tratamiento del mesotelioma maligno pleural.

Malignant pleural mesothelioma is an occupational tumor caused by asbestos exposure. In Mexico, as asbestos usage is not prohibited, an increase in the number of cases is expected. Asbestos exposure is ubiquitous due to the great amount of products in which it is present. Its carcinogenicity is caused as the inhaled asbestos fibers cannot be eliminated by macrophages and, thus, they travel to the pleura through lymphatic pathways, producing a persistent inflammatory response. Diagnosis approach includes occupational history, along with clinical signs and symptoms, and paraclinical studies, such as pleural fluid cytology, chest x-rays, computed tomography, magnetic resonance imaging, and biopsy with immunohistochemistry. The main differential diagnosis is lung adenocarcinoma. Regarding the treatment of this tumor, it mainly comprises palliative care, even though chemotherapy, radiotherapy, and, in selected cases, surgical treatments have been used. There is an urgent need for general physicians and specialists to identify asbestos exposure, in order to make a timely diagnosis. Research is necessary to develop screening and prompt diagnostic tools, along with an epidemiological surveillance program for the workers and the general population exposed to asbestos.

El mesotelioma maligno pleural es un tumor ocupacional ocasionado por la exposición a cualquier tipo de fibra de asbesto. Y dado que en México el uso del asbesto no está prohibido, se espera que la incidencia de este tumor siga aumentando. La exposición al asbesto es ubicua, debido a la gran diversidad de productos en los que se encuentra. Su carcinogenicidad está dada porque las fibras de asbesto inhaladas no pueden ser eliminadas por los macrófagos y viajan hacia la pleura por vía linfática, donde producen una reacción inflamatoria persistente. Para su diagnóstico se precisa de una historia clínica laboral, además de que hay que orientarse con base en el cuadro clínico y los estudios paraclínicos, como la citología de líquido pleural, radiografía de tórax, tomografía axial computarizada, resonancia magnética y biopsia con inmunohistoquímica. El principal diagnóstico diferencial es el adenocarcinoma de pulmón. El tratamiento es principalmente paliativo, aunque se ha utilizado quimioterapia, radioterapia y, en seleccionados casos, cirugía. Para lograr un diagnóstico oportuno y certero es de vital importancia identificar las exposiciones al asbesto. Por otra parte, es necesaria la investigación para desarrollar pruebas de diagnóstico temprano y tamizaje, además de un programa de vigilancia epidemiológica para los trabajadores y la población general expuesta al asbesto.

Blood lead determinants and the prevalence of neuropsychiatric symptoms in firearm users in Mexico.

OBJECTIVES: To identify blood lead predictors and the prevalence of neuropsychiatric symptoms in firearm users of public security in Mexico. MATERIAL AND METHODS: A cross-sectional study was performed on 65 males. We obtained socio-occupational data and determined venous blood lead (blood (B), lead (Pb) - BPb), as well as neuropsychiatric symptoms using the Q-16 questionnaire. A multiple linear regression model was constructed to assess determinants of BPb. RESULTS: The mean age in the study group was 34.8 years (standard deviation (SD) = 6.9, range: 21-60); the mean number of years spent in the company amounted to 14 years (SD = 8.5, range: 1-48). Twenty percent of the respondents (N = 13) used leaded glazed clay pottery (lead (Pb), glazed (G), and clay pottery (C) - PbGC) in the kitchen. During practice they fired a mean of 72 shots (SD = 60, range: 20-250), and during their whole duration of employment 5483 shots (SD = 8322.5, range: 200-50 000). The mean BPb was 7.6 µg/dl (SD = 6.8, range: 2.7-51.7). Two caretakers from the firing range had 29.6 µg/dl and 51.7 µg/dl BPb. The subjects who had shooting practice sessions ≥ 12 times a year reported a greater percentage of miscarriages in their partners (24% vs. 0%). Twelve percent of the respondents showed an increase in neuropsychiatric symptoms. The BPb multiple linear regression model explained R2 = 44.15%, as follows: those who had ≥ 12 practice sessions per year - ß = 0.5339 and those who used PbGC - ß = 0.3651. CONCLUSIONS: Using firearms and PbGC contributes to the increased BPb in the studied personnel. The determinants of BPb were: shooting practices >12 times a year and using PbGC. Blood lead concentrations reported in the study, despite being low, are a health risk, as evidenced by the prevalence of neuropsychiatric symptoms.

[Brainstem auditory evoked potentials latencies, by age and sex, among Mexican adult population]. / Latencias de los potenciales evocados auditivos del tallo cerebral, por edad y sexo, en población adulta mexicana.

BACKGROUND: Brainstem auditory evoked potentials (BAEP) evaluate the auditory pathway, and are a complementary test for tone audiometry in evaluating auditory diseases. The aim of the study was to determine BAEP mean latencies of waves and intervals, among healthy adults. METHODS: Cross-sectional study, comprising 196 subjects, aged 16 to 65 years, without auditory diseases, to whom family and personal history were asked, physical examination and laboratory studies were made, as well as tonal audiometry, impedanciometry and BAEP. RESULTS: A total of 107 men and 89 women were studied. The mean latency periods of waves I, III and V, and intervals I-III, III-V and I-V from both ears were similar. An increase in the latency periods for each age category was observed. Latency periods were significantly shorter in women compared to men. The predictors that increased the latency periods in the multiple linear regression models for waves and intervals were male gender and age ≥45 years. CONCLUSIONS: Age and sex were the variables that showed more statistical power to explain the latencies' differences.

Introducción: los potenciales evocados auditivos del tallo cerebral (PEATC) evalúan la vía auditiva central y son una herramienta complementaria de la audiometría tonal para analizar enfermedades auditivas. El objetivo de este estudio fue determinar el tiempo promedio de las latencias de las ondas y los intervalos de los potenciales evocados auditivos en adultos sanos. Métodos: estudio transversal que contó con 196 participantes, de 16 a 65 años de edad normo-oyentes, a quienes se investigaron antecedentes familiares y personales patológicos, se realizó exploración física y se obtuvieron estudios de laboratorio, audiometría tonal e impedanciometría normales, y potenciales evocados auditivos. Resultados: Se estudiaron 107 hombres y 89 mujeres. El promedio de las latencias de las ondas I, III y V e intervalos I-III, III-V y I-V de ambos oídos fueron similares. Los predictores que incrementaron el tiempo de latencia en los modelos de regresión lineal múltiple de las ondas e intervalos fueron el sexo masculino y la edad ≥ 45 años. Conclusiones: la edad y el sexo fueron las variables que mostraron mayor poder estadístico para explicar las diferencias de las latencias en este grupo de personas.

[Historical and social perspective from the 64-65 Mexican medical movement]. / Perspectiva histórica y social del Movimiento Médico de 1964-1965 en México.

The Mexican Medical Movement from 1964-1965 constitutes an important event from the rising urban middle-class, besides it was the first time medical doctors claimed for fair working conditions. The background of this movement is the so-called Crisis of 1958, which included the Movements from the educators union, oil workers union, telegraph workers union and the railroad workers union. The conflict began because interns and residents from the "Hospital 20 de Noviembre" would not get a payment at the end of the year, so on November 26th, 1964, the movement started. The Asociación Mexicana de Médicos Residentes e Internos (AMMRI) was created and their demands were the following: 1) Full working site restitution without retaliations, 2) Legal examination of the scholarship-contract terms, in order to get annual, renewable and progressive contracts, and a fixed salary with the usual working-hours and characteristics of each institution, 3) To have preference to get an adscription at the hospital where the resident studied, 4) Active participation from the resident in the elaboration of the academic plans, and 5) Resolution of each hospital's problems. This movement had social impact for Mexico's contemporary life, nevertheless some of the demands are still unchanged among medical residents.

El movimiento médico mexicano de 1964-1965 constituyó parte del primer despertar de la clase media urbana, además de haber sido la primera vez que los médicos reclamaron condiciones de trabajo justas. Como antecedente se tiene la llamada crisis de 1958, la cual incluyó los movimientos: revolucionario del Magisterio, del Sindicato de Trabajadores Petroleros, de la Alianza de Telegrafistas, y del Sindicato de Trabajadores Ferrocarrileros de la República Mexicana. El comienzo del conflicto médico se debió a que los residentes e internos del Hospital 20 de Noviembre del hoy Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado (ISSSTE) no recibieron su aguinaldo, por lo que el 26 de noviembre de 1964 inició el paro, a partir del cual se formó la Asociación Mexicana de Médicos Residentes e Internos (AMMRI), cuyas demandas fueron: 1) Restitución total en sus puestos, sin represalias, 2) Revisión legal y cambio de los términos del contrato-beca, en el sentido de lograr contratos de trabajo anuales, renovables y progresivos, con el horario y características acostumbrados en cada institución además de determinación de sueldos base, 3) Preferencia para ocupar plaza de médico adscrito a los residentes egresados de las propias instituciones, 4) Participación activa del residente en la elaboración de los planes de enseñanza, y 5) Resolución de los problemas de cada hospital. Este movimiento, aunque tuvo repercusiones sociales para la vida contemporánea en México, a 50 años de su inicio, algunas de las demandas siguen sin ser resueltas para los médicos residentes.

[Overview of sharps injuries among health-care workers]. / Panorama de heridas por objetos punzocortantes en trabajadores intrahospitalarios.

Sharps injuries are one of the most frequent health-care related accidents. It is estimated globally that 35 million workers are at risk; in Mexico there is no data available for this type of injuries. They are associated with lack of training, instrument and procedure risk, fatigue and stress. The occupational distribution is nurses 45 %, technicians 20 %, doctors 20 % and maintenance workers 5 %. The most commonly associated procedures are injection, venipuncture, suture, and insertion and manipulation of IV catheters. Hepatitis B is the most commonly transmitted agent. Emotional distress is huge as well as the cost of prophylaxis and follow-up. More than half of the injuries are not notified. The most common reasons for not reporting are: the belief that the exposure has low risk of infection, the lack of knowledge of reporting systems and the assumption that it is difficult to notify. Many strategies have been created to reduce the incidence of sharps injuries, such as: identifying the risk of blood exposure, the creation of politics to minimize the risk, the education and training to create a safe workplace, the enhancing of the reporting system, the use of double-gloving and using safety-engineered sharps devices. In many countries these politics have reduced the incidence of sharps injuries as well as the economic burden.

Las heridas por objetos punzocortantes son uno de los accidentes intrahospitalarios más frecuentes. A nivel mundial se estima que 35 millones de trabajadores de la salud se encuentran en riesgo; en México no se tienen datos actualizados para estas heridas. Los accidentes están relacionados con falta de entrenamiento, características de los instrumentos y procedimientos, y fatiga y estrés de quien los practica. La distribución por ocupación es: enfermeras 45 %, técnicos 20 %, médicos 20 % y mantenimiento 5 %. Los procedimientos asociados son: inyección, venopunción, sutura, manipulación e inserción de catéter intravenoso. La infección más comúnmente transmitida es la hepatitis B. La afectación emocional por ansiedad es grande al igual que los costos por profilaxis y seguimiento. Más de la mitad de las heridas por punzocortantes no son notificadas. Las razones más comunes para no reportar son: la suposición de que hay bajo riesgo de infección, la falta de conocimientos sobre métodos de reporte y la creencia de que es difícil notificar. Numerosas estrategias han sido creadas para reducir la incidencia, por ejemplo: la identificación del riesgo de exposición a sangre, la creación de procesos y políticas, la educación y el entrenamiento para laborar en un ambiente seguro, asícomo alentar el reporte de accidentes, el uso de doble enguantado y la utilización de dispositivos de seguridad. En varios países, estas políticas han logrado disminuir la incidencia de heridas por punzocortantes a la vez que se ha generado un ahorro para los sistemas de salud.

Increased Cardiovascular Risk Using Atherogenic Index Measurement Among Healthcare Workers.

BACKGROUND AND AIMS: Cardiovascular diseases are one of the leading causes of death worldwide. This burden of disease is particularly high among healthcare workers. The aim of the study was to identify determinants that increase atherogenic index among healthcare workers. METHODS: In 1,678 healthcare workers, cardiovascular risk factors were analyzed: body mass index, waist-to-hip ratio, systolic and diastolic blood pressure, glucose, total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides. Atherogenic index was calculated and determinants were identified. RESULTS: Mean (SD) age was 41.2 (8.4) years; body mass index 28.4 (4.8); waist-hip-ratio 0.88 (0.07); glucose 96.6 (22.2) µg/dL; TC 195.3 (50.3) mg/dL; HDL 49.0 (16.3) mg/dL; LDL 112.7 (35.0) mg/dL; triglycerides 171.7 (121.2) mg/dL; and atherogenic index 3.3 (1.5). Overweight and obesity prevalence was 77.2%. In the multiple linear regression model, the coefficients for AI were being a physician ß = 0.381, male gender = 0.443, BMI ß = 0.35, waist-to-hip ratio ß = 2.15, age = 0.014, and triglycerides ß = 0.915. CONCLUSIONS: The main contributors to atherogenic index increase were male sex, increased age, waist-to-hip ratio increase, overweight and obesity, high triglyceride levels and working as a physician. Although waist-to-hip ratio was the most powerful determinant, the physician occupational category added risk factors such as stress and adverse psychosocial working conditions, which may potentiate cardiovascular diseases.

[Concordance in blood lead quantification between laboratories]. / Concordancia interlaboratorios en la cuantificación de plomo en la sangre.

OBJECTIVE: To establish a blood lead quantification correlation from two occupational health laboratories (OHL1V and OHL2DF), and the ABC Hospital (LABC) metals laboratory. METHODS: A cross-sectional study was performed in 84 workers from a voltage regulators company, where lead is welded; in 54 % (46 of them) a blood sample was taken and analyzed by OHL1V, and in 28.6 % (24) by OHL2DF. All samples were analyzed by atomic absorption spectrophotometry. Pearson correlation (r), coefficient of determination (r2), Lin (rho) concordance test, and Bland-Altman plots were calculated. RESULTS: The blood lead mean: LABC was 5.8 ± 2.4 µg/dL vs. OHL2DF of 4.4 ± 3.6 µg/dL (r = 0.25 [p = 0.24], r2 = 0.06 [p = 0.24], and rho = 0.21 [p = 0.21]). And with LABC, 6.75 ± 3.3 µg/dL vs. OHL1V 5.6 ± 2.9 µg/dL (r = 0.91 [p < 0.001], r2 = 0.83 [p < 0001], and rho = 0.85 [p< 0.001]). CONCLUSIONS: Agreement between LABC and OHL1V was poor (< 0.90), and with OHL2DF was null. An occupational health laboratory certification is needed in order to have reliable biological exposure index measurements in lead occupational exposure.

OBJETIVO: determinar la concordancia de las cuantificaciones del plomo en la sangre de dos laboratorios del Instituto Mexicano del Seguro Social (LST1V y LST2DF), con las del Laboratorio de Metales del Hospital ABC (LABC). MÉTODOS: se realizó un estudio transversal en 84 trabajadores que sueldan con plomo en una empresa de reguladores. Se tomaron muestras de sangre; 100 % fue analizado por el LABC, 54 % (46) por el LST1V y 28.6 % (24) por el LST2DF. Todas las muestras se analizaron por espectrofotometría de absorción atómica. Se calculó la correlación de Pearson (r), el coeficiente de determinación (r2), la concondancia de Lino (rho) y las gráficas de Bland-Altman. RESULTADOS: las muestras analizadas en el LST2DF indicaron 4.4 ± 3.6 µg/dL de plomo en la sangre y en el LABC, 5.8 ± 2.4 µg/dL (r = 0.25 [p = 0.24], r2 = 0.06 [p = 0.24] y rho = 0.21 [p = 0.21]). Las muestras analizadas en el LST1V indicaron 5.6 ± 2.9 µg/dL y en el LABC, 6.75 ± 3.3 µg/dL (r = 0.91 [p< 0.001], r2 = 0.83 [p< 0.001] y rho = 0.85 [p< 0.001]). CONCLUSIONES: los resultados del LABC concordaron pobremente con los del LST1V (< 0.90) y no lo hicieron con los del LST1-DF. Es necesario certificar a los laboratorios institucionales y acreditar a los técnicos que realizan los análisis, para obtener resultados confiables de los indicadores biológicos de exposición ocupacional.

Production of IL-10, TNF and IL-12 by peripheral blood mononuclear cells in Mexican workers exposed to a mixture of benzene-toluene-xylene.

BACKGROUND AND AIMS: Occupational exposure to low-level benzene and the joint action of toluene-xylene probably cause effects on circulating monocytes immune response. We undertook this study to determine relationship between occupational exposure to benzene-toluene-xylene mixture (BTX) and IL-10, TNF and IL-12 production by peripheral blood mononuclear cells. METHODS: Exposure was estimated in 54 workers from a paint company in Mexico City through BTX accumulated potential dose (BTX-APD). Two exposure groups were formed: high and low BTX-APD established with a cutoff point at ≥1.0 of BTX-APD, as a function of the geometric mean of the estimator's value distribution and the higher agreement between BTX-APD ≥1.0 and the areas referred as using (or not) organic solvents in the work process. IL-10, TNF and IL-12 concentrations were measured with ELISA. Through multiple linear regression models, the production of each of the proposed cytokines and of the whole set was assessed. RESULTS: Workers with high BTX-APD showed a significant reduction in TNF production (ß = -1,196.0 pg/mL; p = 0.01); a reduction for IL-10 (ß = -520.3; p = 0.13) and IL-12 (ß = -843.3; p = 0.09) was also observed, although without statistical significance. CONCLUSIONS: TNF production assessed in workers with a high BTX-APD is lower than in those with a low BTX-APD, but not in IL-10 and IL-12 production.

Alteraciones neuropsicológicas por exposición crónica a concentraciones bajas de monóxido de carbono en trabajadores de autopista de peaje de México / Neuropsychological alterations by chronic exposure to low concentrations of carbon monoxide in highway workers of Mexico

ANTECEDENTES: Trabajadores de la industria automovilística, estaciones de servicio, autopistas de peaje, estacionamientos y los que laboran en las calles, están en contacto crónico con bajas concentraciones de monóxido de carbono (CO) y, por lo tanto, en riesgo de sufrir alteraciones en los sistemas cardiovascular, hematológico y nervioso. OBJETIVO: Identificar la relación de las alteraciones neuropsicológicas con la exposición crónica a bajas concentraciones de CO, en trabajadores de autopistas de peaje. MÉTODO: Estudio transversal en 72 trabajadores de autopistas de peaje de la carretera México-Puebla; 60 cajeros y 12 encargados de turno. Se exploraron variables socio-demográficas, clínicas y ocupacionales, y se determinó hemoglobina (Hb), hematocrito (Htc) y carboxihemoglobina (COHb) en sangre. Se aplicaron pruebas neuropsicológicas (Carbon monoxide neuropsychological screening battery CONSB). Los encargados de turno conformaron el grupo menos expuesto y los cajeros el de mayor exposición a CO. RESULTADOS: En 49 trabajadores, Hb: 18.1±1.9 mg/dL y Htc: 55.3±8.7, sin diferencias significativas entre grupos (p = 0.82). Se observó menor desempeño en el grupo más expuesto, en el test de dígitos y símbolos (p = 0.012), senderos B (p = 0.002) y dígitos (p = 0.003). El test de construcción con bloques resultó limítrofe (p = 0.07). DISCUSIÓN Y CONCLUSIÓN: El grupo de mayor exposición al CO tuvo menor desempeño en percepción visual, codificación, percepción visomotora y memoria inmediata. Por ello, consideramos importante realizar vigilancia epidemiológica en los trabajadores, para intervenir en los casos con alteraciones en las pruebas. Asimismo, se debe evitar la percepción de que la exposición crónica al CO en estos trabajadores es inocua.

BACKGROUND: Workers of the automobile industry, service stations and those working in the streets, are in chronic contact to low concentrations of carbon monoxide and at risk to damage the cardiovascular, haematology and nervous systems. OBJECTIVE: Identify erythrocytosis and neuropsychological alterations in highway workers chronically exposed to low concentrations of CO. METHOD: Cross-sectional study that included 72 workers of the Mexico-Puebla Highway cabins (guards); 60 cashiers and 12 workers in charge of the shift, in which socio-demographic, clinical and occupational variables were explored; haemoglobin(Hb), hematocrit (Htc) and carboxyhemoglobin (COHb) was determined in their blood, and it was applied the Carbon monoxide neuropsychological screening battery (CONSB). The workers who are in charge of the full shift integrated the less exposed to CO group, while the cashiers would shape the greater exposure group. RESULTS: In 49 workers, Hb: 18.1±1.9 mg/dL and Htc: 55.3±8.7 without significant differences between groups (p=0.82). The greater alteration was identified in the exposed group in the test of digit symbol (p= 0.012), trail-making part B (p= 0.002), and digit span (p=0.003); the test of blocks design resulted borderline (p=0.07). DISCUSSION AND CONCLUSIÓN: The group with the highest exposure to CO had lower performance in visual perception, encoding, visual-motor perception and immediate memory. Therefore important to consider epidemiological surveillance workers to intervene in cases with abnormal tests. The perception of innocuousness of chronic exposure to CO in these workers must avoid.

Prevalencia del síndrome de fatiga crónica en trabajadores de una fábrica mexicana de cierres / Prevalence of the chronic fatigue syndrome in workers of a Mexican factory of zippers

Antecedentes: El síndrome de fatiga crónica (SFC) se caracteriza por cansancio persistente e inexplicado a pequeños esfuerzos tanto físicos como mentales, y suele acompañarse de un contexto sintomático tipo inflamatorio; su curso crónico y persistente ocasiona limitación funcional. Es una entidad subdiagnosticada y de etiología múltiple: puede ser infecciosa, de origen ambiental, tóxico y psicosocial; con prevalencia que oscila entre el 2,6% y el 2,8% en la población general; su frecuencia en población trabajadora ha sido muy poco explorada. Objetivo: Determinar la prevalencia del SFC en trabajadores de una fábrica de cierres del estado de Hidalgo, México. Métodos: Estudio transversal que incluyó una muestra por conveniencia no aleatoria de 137/152 (90%) trabajadores de una fábrica de cierres localizada en el estado de Hidalgo, México, y en quienes se exploraron diversas variables sociodemográficas, clínicas y laborales; para el diagnóstico de SFC se aplicaron los criterios del Centro de Control de Enfermedades (CDC) 1994. Se realizó análisis simple descriptivo con cálculo de prevalencia puntual. Resultados: En la población trabajadora estudiada se encontró una prevalencia de 19,71%, sin encontrar diferencias proporcionales de las variables estudiadas, excepto en su distribución por sexo (p<0,05) con predominio del sexo femenino. Conclusión: La prevalencia de SFC en el grupo de trabajadores estudiados fue más elevada que la referida en población general. Los resultados se apegan a la idea que el trabajo podría contribuir de manera importante al desarrollo de SFC.

Background: Chronic fatigue syndrome (CFS) is characterized by persistent fatigue and unexplained to small physical and mental effort, and usually accompanied by an inflammatory symptomatic context, its course is chronic and persistent that cause functional limitation. It is an underdiagnosed entity with multiple etiologies: it may be infectious, environmental, toxic or psychological, with prevalence that ranges between 2,6% and 2,8% in the general population, its frequency among workers has been very little explored. Objective: To determine the prevalence of CFS in workers at a zipper factory in the state of Hidalgo, Mexico. Methods: Cross-sectional study included a non random convenience sample of 137/152 (90%) workers in a factory zippers located in the state of Hidalgo, Mexico, and who were explored in several sociodemographic, clinical and labor variables; for CFS diagnose criteria of the Center for Disease Control (CDC) 1994 were applied. Simple descriptive analysis was performed to estimate punctual prevalence. Results: We determined prevalence of 19.71% in the working population studied, no differences in proportion of the studied variables, except sex distribution (p <0.05) with female predominance. Conclusion: CFS prevalence in the group of workers studied was higher than that reported in general population. Results agree with the idea that work could contribute significantly to CFS development.