Hasil untuk "Industrial medicine. Industrial hygiene"

Yingyue Ni, Prathiba Balakumar, Tariqul Islam et al.

Abstract Background Arsenic is a pervasive environmental contaminant and a recognized global public health concern. Experimental evidence suggests that arsenic may disrupt endocrine signaling during critical developmental windows, yet epidemiologic data on its effects on thyroid function in early childhood remain limited. Methods We investigated the cross-sectional association between arsenic exposure and free thyroxine (fT4) levels among 496 children aged 5 to 7 years enrolled in the Bangladesh Environmental Research in Children’s Health (BiRCH) cohort. Arsenic exposure was assessed using urinary total arsenic and toenail arsenic concentrations. Serum fT4 levels were measured by an enzyme-linked immunosorbent assay (ELISA) kit. Associations with fT4 were estimated using multivariable linear regression models adjusted for child age, sex, body mass index, and environmental tobacco smoke exposure. Results The median urinary and toenail arsenic concentrations were 88.0 µg/L (interquartile range [IQR]: 127.4) and 1.7 µg/g (IQR: 2.0), respectively. Children in the highest quartile (Q4) of arsenic exposure had significantly higher fT4 levels compared to those in the lowest quartile (Q1), for both urinary (β = 0.09; 95% CI: 0.005–0.17) and toenail arsenic (β = 0.10; 95% CI: 0.03–0.17). A significant dose-response trend was observed across quartiles, suggesting a potential linear relationship. Conclusions Our findings suggest that thyroid function may be a sensitive target of arsenic toxicity in early childhood. Longitudinal studies are necessary to assess the long-term effects of early-life arsenic exposure on thyroid function across the life course.

Miki Tanaka, Tomoaki Okuda, Kouichi Itoh et al.

Abstract Background A recent epidemiological study showed that air pollution is closely involved in the prognosis of ischemic stroke. We and others have reported that microglial activation in ischemic stroke plays an important role in neuronal damage. In this study, we investigated the effects of urban aerosol exposure on neuroinflammation and the prognosis of ischemic stroke using a mouse photothrombotic model. Results When mice were intranasally exposed to CRM28, urban aerosols collected in Beijing, China, for 7 days, microglial activation was observed in the olfactory bulb and cerebral cortex. Mice exposed to CRM28 showed increased microglial activity and exacerbation of movement disorder after ischemic stroke induction. Administration of core particles stripped of attached chemicals from CRM28 by washing showed less microglial activation and suppression of movement disorder compared with CRM28-treated groups. CRM28 exposure did not affect the prognosis of ischemic stroke in null mice for aryl hydrocarbon receptor, a polycyclic aromatic hydrocarbon (PAH) receptor. Exposure to PM2.5 collected at Yokohama, Japan also exacerbated movement disorder after ischemic stroke. Conclusion Particle matter in the air is involved in neuroinflammation and aggravation of the prognosis of ischemic stroke; furthermore, PAHs in the particle matter could be responsible for the prognosis exacerbation.

David Welch, Kim N Dirks, Daniel Shepherd et al.

Background: Noise sensitivity moderates the association between environmental noise exposure and annoyance and health outcomes. Methods: In normally hearing adults, we measured noise sensitivity in three ways: using the noise sensitivity questionnaire, a 3-point self-rating, and the loudness discomfort level (LDL; mean reported discomfort level for tone bursts). We then presented recordings of a 15-second 80 dBLAeq aeroplane overflight and participants rated the annoyance and loudness they experienced. Results: The three measures of noise sensitivity were not well correlated with each other, and only the overall LDL was associated with the ratings of loudness and annoyance in response to the aeroplane sounds. Conclusions: This implies that our current measures of noise sensitivity may only capture parts of the underlying construct, and therefore underestimate effects due to it on the association between environmental noise and annoyance and health outcomes. We developed a theoretical model to describe the set of factors that may influence a person’s sensitivity to noise and propose that interaction between the systems described is the basis for noise sensitivity. This paradigm alters the focus of noise research from the annoyance caused by the sound, to the sensitization to noise that may occur as a result of the interplay of many factors. We hope that our model will allow research to explore the sensitizing factors for noise more easily and systematically.

Yaguang Wei, Mahdieh Danesh Yazdi, Qian Di et al.

Abstract Background Fine particulate matter (PM2.5), ozone (O3), and nitrogen dioxide (NO2) are major air pollutants that pose considerable threats to human health. However, what has been mostly missing in air pollution epidemiology is causal dose-response (D-R) relations between those exposures and mortality. Such causal D-R relations can provide profound implications in predicting health impact at a target level of air pollution concentration. Methods Using national Medicare cohort during 2000–2016, we simultaneously emulated causal D-R relations between chronic exposures to fine particulate matter (PM2.5), ozone (O3), and nitrogen dioxide (NO2) and all-cause mortality. To relax the contentious assumptions of inverse probability weighting for continuous exposures, including distributional form of the exposure and heteroscedasticity, we proposed a decile binning approach which divided each exposure into ten equal-sized groups by deciles, treated the lowest decile group as reference, and estimated the effects for the other groups. Binning continuous exposures also makes the inverse probability weights robust against outliers. Results Assuming the causal framework was valid, we found that higher levels of PM2.5, O3, and NO2 were causally associated with greater risk of mortality and that PM2.5 posed the greatest risk. For PM2.5, the relative risk (RR) of mortality monotonically increased from the 2nd (RR, 1.022; 95% confidence interval [CI], 1.018–1.025) to the 10th decile group (RR, 1.207; 95% CI, 1.203–1.210); for O3, the RR increased from the 2nd (RR, 1.050; 95% CI, 1.047–1.053) to the 9th decile group (RR, 1.107; 95% CI, 1.104–1.110); for NO2, the DR curve wiggled at low levels and started rising from the 6th (RR, 1.005; 95% CI, 1.002–1.018) till the highest decile group (RR, 1.024; 95% CI, 1.021–1.027). Conclusions This study provided more robust evidence of the causal relations between air pollution exposures and mortality. The emulated causal D-R relations provided significant implications for reviewing the national air quality standards, as they inferred the number of potential early deaths prevented if air pollutants were reduced to specific levels; for example, lowering each air pollutant concentration from the 70th to 60th percentiles would prevent 65,935 early deaths per year.

Sangram Panda, Shakti Rath, Mirna Garhanayak et al.

Objectives. Antimicrobial efficacy and toxicity analysis of 5 different concentrations of silver zeolite (SZ) compound against 5 common oral pathogens Streptococcus mutans, Streptococcus pyogenes, Lactobacillus sp., Staphylococcus aureus, Candida albicans. Material and methods. The antimicrobial efficacy of 5 different concentrations of SZ was tested against 5 common oral pathogens using the agar well diffusion method and the MIC and MBC values were determined using the micro broth dilution method. The toxicity of all 5 different concentrations was evaluated using brine shrimp assay and lethal concentration (Lc50) value was determined. Results. At 10 μg/mL the antimicrobial activity of SZ was almost negligible. The antimicrobial activity was observed in an increasing trend against all the test microorganisms as the concentration increased. At 75 & 100 μg/mL the zone of inhibitions was more than the control. Furthermore, MIC and MBC values of SZ with concentrations 25, 50, 75, and 100 μg/mL were determined and recorded. SZ was equally effective against all the test organisms. The LC25 (lethal concentration25) value was 1.6 μg/mL, whereas the LC50 value was 1.77 μg/mL and the LC75 value was 1.90 μg/mL, calculated from the probit computational method. Conclusion. SZ has the potential to change the ongoing system and bring about a revolution as an antimicrobial drug. However, the dose must be regulated as it can be toxic in higher concentrations. SZ compounds with the correct study of physicochemical properties and toxicity analysis can increase their pharmacological use and market value.

Keewan Kim, Anna Z. Pollack, Carrie J. Nobles et al.

Abstract Background Cadmium is an endocrine disrupting chemical that affects the hypothalamic-pituitary-gonadal axis. Though evidence suggests its potential role in altering androgen synthesis and metabolic pathways that are characteristic of polycystic ovary syndrome (PCOS), its relation in healthy women of reproductive age is largely unknown. As women with mild sub-clinical features of PCOS who do not meet the diagnostic criteria of PCOS may still experience reduced fecundability, investigating associations between cadmium and PCOS-phenotypes among healthy women may provide unique insight into the reproductive implications for many on the PCOS spectrum. Therefore, the objective of this study was to evaluate associations between cadmium and androgens, anti-Müllerian hormone (AMH), and metabolic markers in women of reproductive age. Methods This was a prospective cohort study of 251 healthy premenopausal women without self-reported PCOS (mean age 27.3 years and BMI 24.1 kg/m2). Cadmium was measured in blood collected at baseline. Reproductive hormones and metabolic markers were measured in fasting serum 8 times per menstrual cycle for 2 cycles. Linear mixed models and Poisson regression with a robust error variance were used to examine associations between cadmium and reproductive hormones and metabolic markers and anovulation, respectively. Results Median (interquartile range) blood cadmium concentrations at baseline were 0.30 (0.19–0.43) µg/L. Higher levels of testosterone (2.2 %, 95 % confidence interval [CI] 0.4, 4.1), sex hormone-binding globulin (2.9 %, 95 % CI 0.5, 5.5), and AMH (7.7 %, 95 % CI 1.1, 14.9) were observed per 0.1 µg/L increase in cadmium concentrations. An 18 % higher probability of a mild PCOS-phenotype (95 % CI 1.06, 1.31), defined by a menstrual cycle being in the highest quartile of cycle-averaged testosterone and AMH levels, was also found per 0.1 µg/L increase in cadmium levels. No associations were observed for insulin and glucose. These findings were consistent even after analyses were restricted to non-smokers or further adjusted for dietary factors to account for potential sources of exposure. Conclusions Overall, among healthy reproductive-aged women, cadmium was associated with endocrine features central to PCOS, but not with metabolic markers. These suggest its potential role in the hormonal milieu associated with PCOS even at low levels of exposure.

Raquel García Vela, Rosa Cabanas Valdés, Santos Huertas Ríos et al.

Introducción: Un componente importante del equipo de protección individual (EPI) frente al SARS-CoV-2 son las mascarillas quirúrgicas y las mascarillas autofiltrantes (FFP). La norma europea EN 149 establece y clasifica las mascarillas autofiltrantes en tres niveles de protección dependiendo del porcentaje de fuga del total de partículas en suspensión del aire exterior hacia el aire interior FFP1, FFP2, FFP3. El objetivo de este e ensayo de laboratorio es determinar y cuantificar el nivel de ajuste de las mascarillas autofiltrantes FFP2 combinadas con las mascarillas quirúrgicas mediante series de pruebas de ajuste (fit test). Material y Métodos: Se utilizó el equipo medidor de ajuste de mascarillas FFP modelo PortaCount® Pro + 8038 compatible con las normas y metodología de la OSHA (Occupational Safety and Health Administration) de los EEUU. Se realizaron series de pruebas de ajuste sobre diferentes modelos de mascarillas autofiltrantes FFP2 con y sin mascarilla quirúrgica para diferentes situaciones de respiración del trabajador participante en este experimento.  Resultados: El uso de la mascarilla quirúrgica sobre una mascarilla autofiltrante FFP2 aporta una mejora en la protección respiratoria determinante, incrementando el factor de ajuste hasta de +200 (el factor de ajuste mínimo debe ser 100). Conclusiones: Las mascarillas quirúrgicas cuando se usan conjuntamente con las mascarillas autofiltrantes, podrían mejorar significativamente el grado de ajuste de todas las mascarillas autofiltrantes proporcionando una mayor eficacia de filtración y una mayor protección al usuario frente a la exposición a aerosoles.

Dong-Keun Lee, Soyeon Jeon, Jiyoung Jeong et al.

Abstract Background The quantification of nanomaterials accumulated in various organs is crucial in studying their toxicity and toxicokinetics. However, some types of nanomaterials, including carbon nanomaterials (CNMs), are difficult to quantify in a biological matrix. Therefore, developing improved methodologies for quantification of CNMs in vital organs is instrumental in their continued modification and application. Results In this study, carbon black, nanodiamond, multi-walled carbon nanotube, carbon nanofiber, and graphene nanoplatelet were assembled and used as a panel of CNMs. All CNMs showed significant absorbance at 750 nm, while their bio-components showed minimal absorbance at this wavelength. Quantification of CNMs using their absorbance at 750 nm was shown to have more than 94% accuracy in all of the studied materials. Incubating proteinase K (PK) for 2 days with a mixture of lung tissue homogenates and CNMs showed an average recovery rate over 90%. The utility of this method was confirmed in a murine pharyngeal aspiration model using CNMs at 30 μg/mouse. Conclusions We developed an improved lung burden assay for CNMs with an accuracy > 94% and a recovery rate > 90% using PK digestion and UV-Vis spectrophotometry. This method can be applied to any nanomaterial with sufficient absorbance in the near-infrared band and can differentiate nanomaterials from elements in the body, as well as the soluble fraction of the nanomaterial. Furthermore, a combination of PK digestion and other instrumental analysis specific to the nanomaterial can be applied to organ burden analysis.

Jun Young Uhm, Hyoung-Ryoul Kim, Gu Hyeok Kang et al.

Abstract Objective Kidneys are organs having a biological clock, and it is well known that the disruption of the circadian rhythm increases the risk of chronic kidney disease (CKD), including the decline of renal and proteinuria. Because shift work causes circadian disruption, it can directly or indirectly affect the incidence of chronic kidney disease. Therefore, the purpose of this study was to investigate the association between shift work and chronic kidney disease using a Korean representative survey dataset. Methods This study was comprised of 3504 manual labor workers over 20 years of age from data from the fifth and sixth Korea National Health and Nutrition Examination Survey (2011–2014). The work schedules were classified into two types: day work and shift work. The estimated glomerular filtration rate, which is the ideal marker of renal function, was estimated according to the Chronic Kidney Disease Epidemiology Collaboration creatinine equation, and chronic kidney disease was defined as urinary albumin to a creatinine ratio equal to or high than 30 mg/g and/or estimated glomerular filtration rate lower than 60 mL/min/1.73 m2. The cross-tabulation analysis and multivariate logistic regression analysis were performed to confirm the association between shift work and chronic kidney disease stratified by gender. Results The risk of CKD showed a significant increase (odds ratio = 2.04, 95% confidence interval = 1.22, 3.41) in the female worker group. The same results were obtained after all confounding variables were adjusted (odds ratio = 2.34, 95% confidence interval = 1.35, 4.07). However, the results of the male worker group were not significant. Conclusions In this study using nationally representative surveys, we found that the risk of CKD was higher female workers and shift work. Future prospective cohort studies will be needed to clarify the causal relationship between shift work and CKD.

Philip J. Scarpa, Jeffrey C. Sventek

Meghan M. Woods, Bruce P. Lanphear, Joseph M. Braun et al.

Abstract Background Pregnant women are exposed to a mixture of endocrine disrupting chemicals (EDCs). Gestational EDC exposures may be associated with changes in fetal growth that elevates the risk for poor health later in life, but few studies have examined the health effects of simultaneous exposure to multiple chemicals. This study aimed to examine the association of gestational exposure to five chemical classes of potential EDCs: phthalates and bisphenol A, perfluoroalkyl substances (PFAS), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs) with infant birth weight. Methods Using data from the Health Outcomes and Measures of Environment (HOME) Study, we examined 272 pregnant women enrolled between 2003-2006. EDC concentrations were quantified in blood and urine samples collected at 16 and 26 weeks gestation. We used Bayesian Hierarchical Linear Models (BHLM) to examine the associations between newborn birth weight and 53 EDCs, 2 organochlorine pesticides (OPPs) and 2 heavy metals. Results For a 10-fold increase in chemical concentration, the mean differences in birth weights (95% credible intervals (CI)) were 1 g (-20, 23) for phthalates, -11 g (-52, 34) for PFAS, 0.2 g (-9, 10) for PCBs, -4 g (-30, 22) for PBDEs, and 7 g (-25, 40) for OCPs. Conclusion Gestational exposure to phthalates, PFAS, PCBs, PBDEs, OCPs or OPPs had null or small associations with birth weight. Gestational OPP, Pb, and PFAS exposures were most strongly associated with lower birth weight.

Tze-Wah Kao, Yueh-Hsia Kuo, Ching-Yuang Lin et al.

This study aimed to evaluate the effects of soy protein and nutrition education on patients with chronic kidney disease (CKD). Patients who were regularly followed up at the nephrology clinics of National Taiwan University Hospital, aged between 18 to 75 years, daily activities-independent, had normal liver function, and had stage III, IV or V CKD were invited to join this study. The enrolled patients were then divided into two groups by simple randomization. Group 1 patients were asked to eat meat while Group 2 patients eat soy bean as their major sources of protein intake for a period of 6 months. Diet education for CKD was given at the start, the 3rd month, and the end of study. Demographic, clinical as well as laboratory data including serum biochemistry, lipid profile, interleukin-6, serum adiponectin, indirect calorimetry, and body composition were compared between the two groups both at the beginning and at the end of study. There were 26 CKD patients who had finished the study, but only 23 of them had complete laboratory data. There was no statistical difference in the baseline demographic, clinical and laboratory data between Group 1 and Group 2 patients except for serum albumin level (4.7±0.2 versus 4.4±0.2 g/dL, P=0.0013) (Table 1). There was neither any statistical difference in the baseline indirect calorimetry and body composition data between the two groups except for body fat percentage (23.1±6.2 versus 28.9±6.5 %, P=0.0380). After 6 months of intervention, Group 2 patients were noted to have significantly higher adiponectin level than Group 1 patients (-3776.0±9118.3 versus 9073.5±9748.1 pg/mL, P=0.0049) (Table 2). There was no statistical difference in indirect calorimetry change or body composition change between the 2 groups though Group 2 patients were on average lighter at the end of study (P=0.0532). In conclusion, patients who ate soy bean as their major sources of protein intake had higher serum adiponectin level. fx1 fx2

Mónica Sánchez Aguilar, Gabriela Betzabé Pérez-Manríquez, Guadalupe González Díaz

La industria de la producción de alimentos presenta factores de riesgo laborales que van de los químicos hasta los psicosociales, por lo mismo los grupos de enfermedades que potencialmente se vinculan con ellos pueden ser aparentemente inocuas o poner en riesgo la vida del trabajador, lo que evidencia la necesidad de contar con una revisión extensa de la bibliografía nacional e internacional de enfermedades vinculadas a los riesgos presentes en los puestos de las áreas de producción hasta los puestos de mantenimiento de la industria de los alimentos. El propósito de esta publicación es evidenciar al lector el vínculo existente entre los factores de riesgos presentes en la industria de los alimentos y las enfermedades que estos pueden generar, y que frecuentemente son calificadas como enfermedades generales cuando en realidad son laborales, y así proporcionarle fundamentos sólidos según referencias nacionales e internacionales para un diagnóstico situacional y de salud más completo. Objetivos: Esta revisión pretende evidenciar el vínculo existente entre los factores de riesgos presentes en la industria de los alimentos y las enfermedades que pueden generarse a consecuencia de estos. Material y Método: Se han revisado hasta Diciembre de 2009 las siguientes bases de datos bibliográficas: Medline, SciELO, y PUBMED. Conclusiones: Un diagnóstico a fondo de enfermedades de presunto origen ocupacional implica el conocimiento y reconocimiento absoluto de los factores de riesgo laborales a los que se exponen los trabajadores diariamente o eventualmente, así como identificar rápidamente los efectos a la salud reales y potenciales de estos factores por parte de todos los responsables, directos e indirectos, de salud ocupacional al interior de los centros de trabajo.<br>The industry of foods production presents occupational hazards that go from chemicals to psychosocial, because of that the groups of diseases that potentially been linked with them can be apparently harmless put in risk the life of the worker, which shows the need to have an extensive review of national and international bibliography of diseases linked with the risks presents in positions of production areas to maintenance positions of food industry. The propose of this publication is make evidence to the reader the link that exist between the risks factor presents in the food industry and the diseases that this can provoke, and frequently been qualified as general diseases when really are work related diseases, and thus provide solid foundations according national and international references for a situational diagnostic and health more complete. Objectives: This review aims to show the link between risk factors presents in food industry and the diseases that may occur as a result of them. Material and Methods: Have been revised to December 2009 the next bibliographic data bases: Medline, SciELO and PUBMED. Conclusions: A thorough diagnosis of diseases of presumptive occupational origin implies knowledge and full recognition that the workers been exposed every day or eventually, as well as quickly identify the real effect to the health and potential effect of these hazards by all those responsive for, direct and indirect, of occupational health within work centers.

Yukio Takahashi

To investigate the contribution of body vibrations to the vibratory sensation induced by high-level, complex low-frequency noise, we conducted two experiments. In Experiment 1, eight male subjects were exposed to seven types of low-frequency noise stimuli: two pure tones [a 31.5-Hz, 100-dB(SPL) tone and a 50-Hz, 100-dB(SPL) tone] and five complex noises composed of the pure tones. For the complex noise stimuli, the sound pressure level of one tonal component was 100 dB(SPL) and that of another one was either 90, 95, or 100 dB(SPL). Vibration induced on the body surface was measured at five locations, and the correlation with the subjective rating of the vibratory sensation at each site of measurement was examined. In Experiment 2, the correlation between the body surface vibration and the vibratory sensation was similarly examined using seven types of noise stimuli composed of a 25-Hz tone and a 50-Hz tone. In both the experiments, we found that at the chest and the abdomen, the rating of the vibratory sensation was in close correlation with the vibration acceleration level (VAL) of the body surface vibration measured at each corresponding location. This was consistent with our previous results and suggested that at the trunk of the body (the chest and the abdomen), the mechanoreception of body vibrations plays an important role in the experience of the vibratory sensation in persons exposed to high-level low-frequency noise. At the head, however, no close correlation was found between the rating of the vibratory sensation and the VAL of body surface vibration. This suggested that at the head, the perceptual mechanisms of vibration induced by high-level low-frequency noise were different from those in the trunk of the body.

Buse John B, Schmitt Mike T, Herbst Margaret C et al.

<p>Abstract</p> <p>Background and Objective</p> <p>Exposure to fine airborne particles (PM_2.5) has been shown to be responsible for cardiovascular and hematological effects, especially in older people with cardiovascular disease. Some epidemiological studies suggest that individuals with diabetes may be a particularly susceptible population. This study examined effects of short-term exposures to ambient PM_2.5on markers of systemic inflammation, coagulation, autonomic control of heart rate, and repolarization in 22 adults (mean age: 61 years) with type 2 diabetes.</p> <p>Methods</p> <p>Each individual was studied for four consecutive days with daily assessments of plasma levels of blood markers. Cardiac rhythm and electrocardiographic parameters were examined at rest and with 24-hour ambulatory ECG monitors. PM_2.5and meteorological data were measured daily on the rooftop of the patient exam site. Data were analyzed with models adjusting for season, weekday, meteorology, and a random intercept. To identify susceptible subgroups, effect modification was analyzed by clinical characteristics associated with insulin resistance as well as with oxidative stress and by medication intake.</p> <p>Results</p> <p>Interleukin (IL)-6 and tumor necrosis factor alpha showed a significant increase with a lag of two days (percent change of mean level: 20.2% with 95%-confidence interval [6.4; 34.1] and 13.1% [1.9; 24.4], respectively) in association with an increase of 10 μg/m³in PM_2.5. Obese participants as well as individuals with elevated glycosylated hemoglobin, lower adiponectin, higher ferritin or with glutathione S-transferase M1 null genotype showed higher IL-6 effects. Changes in repolarization were found immediately as well as up to four days after exposure in individuals without treatment with a beta-adrenergic receptor blocker.</p> <p>Conclusions</p> <p>Exposure to elevated levels of PM_2.5alters ventricular repolarization and thus may increase myocardial vulnerability to arrhythmias. Exposure to PM_2.5also increases systemic inflammation. Characteristics associated with insulin resistance or with oxidative stress were shown to enhance the association.</p>

Arline L Bronzaft

From the latter part of the 19 th century, when New York City trains began to operate, until the present time, New York City′s Transit Authority has received train noise complaints from riders and residents living near its transit system. The growing body of literature demonstrating the adverse effects of noise on physical and mental health raises the question as to whether transit noise is hazardous to the health of New York City′s transit riders and residents living near the transit system. Several studies have examined the impacts of the noise of New York′s transit system on hearing, health and learning. Despite the Transit Authority′s efforts to remedy transit noise in response to complaints, the noise problem has not yet been satisfactorily ameliorated. This paper will suggest how the Transit Authority could employ techniques that could lower the noise levels of its system and benefit the health and welfare of New Yorkers. The recommendations in this paper could also apply to other cities with major transit systems where noise abatement has not been treated seriously.

Pukkala Eero, Jaakkola Maritta S, Khalade Abdul et al.

<p>Abstract</p> <p>Background</p> <p>A substantial number of epidemiologic studies have provided estimates of the relation between exposure to benzene at work and the risk of leukemia, but the results have been heterogeneous. To bridge this gap in knowledge, we synthesized the existing epidemiologic evidence on the relation between occupational exposure to benzene and the risk of leukemia, including all types combined and the four main subgroups acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), chronic lymphocytic leukemia (CLL), and chronic myeloid leukemia (CML).</p> <p>Methods</p> <p>A systematic literature review was carried out using two databases 'Medline' and 'Embase' from 1950 through to July 2009. We selected articles which provided information that can be used to estimate the relation between benzene exposure and cancer risk (effect size).</p> <p>Results</p> <p>In total 15 studies were identified in the search, providing 16 effect estimates for the main analysis. The summary effect size for any leukemia from the fixed-effects model was 1.40 (95% CI, 1.23-1.57), but the study-specific estimates were strongly heterogeneous (I²= 56.5%, Q stat = 34.47, p = 0.003). The random-effects model yielded a summary- effect size estimate of 1.72 (95% CI, 1.37-2.17). Effect estimates from 9 studies were based on cumulative exposures. In these studies the risk of leukemia increased with a dose-response pattern with a summary-effect estimate of 1.64 (95% CI, 1.13-2.39) for low (< 40 ppm-years), 1.90 (95% CI, 1.26-2.89) for medium (40-99.9 ppm-years), and 2.62 (95% CI, 1.57-4.39) for high exposure category (> 100 ppm-years). In a meta-regression, the trend was statistically significant (P = 0.015). Use of cumulative exposure eliminated heterogeneity. The risk of AML also increased from low (1.94, 95% CI, 0.95-3.95), medium (2.32, 95% CI, 0.91-5.94) to high exposure category (3.20, 95% CI, 1.09-9.45), but the trend was not statistically significant.</p> <p>Conclusions</p> <p>Our study provides consistent evidence that exposure to benzene at work increases the risk of leukemia with a dose-response pattern. There was some evidence of an increased risk of AML and CLL. The meta-analysis indicated a lack of association between benzene exposure and the risk of CML.</p>

Rocío Manchado Garabito, Sonia Tamames Gómez, María López González et al.

Debido al gran avance que se ha producido en los últimos años en el ámbito de la investigación científica, no sólo disponemos cada vez de más información si no que esta es a su vez más compleja. Las revisiones exploratorias permiten sintetizar la evidencia existente respecto a un tema en salud incorporando diferentes diseños de estudio, intervenciones y medidas de impacto con el fin de generar nuevas hipótesis, líneas de investigación o proponer métodos de trabajo más adecuados para futuras investigaciones. Esto es posible aplicando criterios de evaluación de la calidad de los documentos encontrados y del grado de evidencia científica.<br>Due to the great progress that has occurred in recent years in the field of scientific research, the information is increasing not just in terms of amount but also in complexity. The scoping reviews allow to synthesize the existing evidence regarding a health issue, incorporating different study designs, interventions and measures of impact in order to generate new hypotheses, lines of research or to propose most appropriate working methods for future research. This is possible by applying criteria for assessing the quality of the documents found and the levels of scientific evidence.

P. Taylor, Y. Qiao, A. Schatzkin et al.

A. Lee-Feldstein