Strabismus, visual acuity, and uncorrected refractive error in portuguese children aged 6 to 11 years.

INTRODUCTION: Visual anomalies that affect school-age children represent an important public health problem. Data on the prevalence are lacking in Portugal but is needed for planning vision services. This study was conducted to determine the prevalence of strabismus, decreased visual acuity, and uncorrected refractive error in Portuguese children aged 6 to 11 years. METHODS AND MATERIALS: A cross-sectional study was carried out on a sample of 672 school-age children (7.69±1.19 years). Children received an orthoptic assessment (visual acuity, ocular alignment, and ocular movements) and non-cycloplegic autorefraction. RESULTS: After orthoptic assessment, 13.8% of children were considered abnormal (n=93). Manifest strabismus was found in 4% of the children. Rates of esotropia (2.1%) were slightly higher than exotropia (1.8%). Strabismus rates were not statistically significant different per sex (p=0.681) and grade (p=0.228). Decreased visual acuity at distance was present in 11.3% of children. Visual acuity≤20/66 (0.5 logMAR) was found in 1.3% of the children. We also found that 10.3% of children had an uncorrected refractive error. CONCLUSIONS: Strabismus affects a small proportion of the Portuguese school-age children. Decreased visual acuity and uncorrected refractive error affected a significant proportion of school-age children. New policies need to be developed to address this public health problem.

Genotoxic effects of occupational exposure to lead and influence of polymorphisms in genes involved in lead toxicokinetics and in DNA repair.

Lead is still widely used in many industrial processes and is very persistent in the environment. Although toxic effects caused by occupational exposure to lead have been extensively studied, there are still conflicting results regarding its genotoxicity. In a previous pilot study we observed some genotoxic effects in a population of lead exposed workers. Thus, we extended our study analysing a larger population, increasing the number of genotoxicity endpoints, and including a set of 20 genetic polymorphisms related to lead toxicokinetics and DNA repair as susceptibility biomarkers. Our population comprised 148 workers from two Portuguese factories and 107 controls. The parameters analysed were: blood lead levels (BLL) and δ-aminolevulinic acid dehydratase (ALAD) activity as exposure biomarkers, and T-cell receptor (TCR) mutation assay, micronucleus (MN) test, comet assay and OGG1-modified comet assay as genotoxicity biomarkers. Lead exposed workers showed markedly higher BLL and lower ALAD activity than the controls, and significant increases of TCR mutation frequency (TCR-Mf), MN rate and DNA damage. Oxidative damage did not experience any significant alteration in the exposed population. Besides, significant influence was observed for VDR rs1544410 polymorphism on BLL; APE1 rs1130409 and LIG4 rs1805388 polymorphisms on TCR-Mf; MUTYH rs3219489, XRCC4 rs28360135 and LIG4 rs1805388 polymorphisms on comet assay parameter; and OGG1 rs1052133 and XRCC4 rs28360135 polymorphisms on oxidative damage. Our results showed genotoxic effects related to occupational lead exposure to levels under the Portuguese regulation limit of 70 µg/dl. Moreover, a significant influence of polymorphisms in genes involved in DNA repair on genotoxicity biomarkers was observed.

Biomonitoring of a population of Portuguese workers exposed to lead.

Lead is a heavy metal that has been used for many centuries and it is still used for various industrial purposes thanks to its physical and chemical characteristics. Human exposure to lead can result in a wide range of biological effects depending upon the level and duration of exposure. Despite the fact that lead has been found capable of eliciting genotoxic responses in a wide range of tests, not all studies have been conclusive. Although several experimental studies have shown that lead may modulate immune responses, data in exposed humans are still preliminary. The purpose of our study was to evaluate the genotoxic and immunotoxic effects of lead exposure in a group of 70 male workers from two Portuguese factories. The control group comprised 38 healthy males. The exposed individuals showed significantly higher levels of lead in blood and zinc protoporphyrin, and significantly lower δ-aminolevulinic acid dehydratase activity than the controls, suggesting a relatively high lead exposure. Nevertheless, the limit of 70 µg/dl for lead in blood established by the Portuguese regulation was never reached. Results of the comet assay were not modified by the exposure, but a significant increase in the mutation frequency in the exposed workers was obtained in the T-cell receptor mutation assay. Furthermore, data obtained in the analysis of the different lymphocyte subsets showed a significant decrease in %CD8+ cells and a significant increase in the %CD4+/%CD8+ ratio in exposed individuals with regard to the controls. No clear effect was observed for vitamin D receptor genetic polymorphism on the parameters evaluated. In view of our results showing mutagenic and immunotoxic effects related to lead exposure in occupational settings, it seems that the Portuguese biological exposure limit for lead needs to be revised in order to increase the safety of exposed workers.

Genotoxicity biomarkers in occupational exposure to formaldehyde--the case of histopathology laboratories.

Formaldehyde, classified by the IARC as carcinogenic in humans and experimental animals, is a chemical agent that is widely used in histopathology laboratories. The exposure to this substance is epidemiologically linked to cancer and to nuclear changes detected by the cytokinesis-block micronucleus test (CBMN). This method is extensively used in molecular epidemiology, since it provides information on several biomarkers of genotoxicity, such as micronuclei (MN), which are biomarkers of chromosomes breakage or loss, nucleoplasmic bridges (NPB), common biomarkers of chromosome rearrangement, poor repair and/or telomere fusion, and nuclear buds (NBUD), biomarkers of elimination of amplified DNA. The aim of this study is to compare the frequency of genotoxicity biomarkers, provided by the CBMN assay in peripheral lymphocytes and the MN test in buccal cells, between individuals occupationally exposed and non-exposed to formaldehyde and other environmental factors, namely tobacco and alcohol consumption. The sample comprised two groups: 56 individuals occupationally exposed to formaldehyde (cases) and 85 unexposed individuals (controls), from whom both peripheral blood and exfoliated epithelial cells of the oral mucosa were collected in order to measure the genetic endpoints proposed in this study. The mean level of TWA(8h) was 0.16±0.11 ppm (

Genotoxic effects in occupational exposure to formaldehyde: A study in anatomy and pathology laboratories and formaldehyde-resins production.

BACKGROUND: According to the Report on Carcinogens, formaldehyde ranks 25th in the overall U.S. chemical production, with more than 5 million tons produced each year. Given its economic importance and widespread use, many people are exposed to formaldehyde environmentally and/or occupationally. Presently, the International Agency for Research on Cancer classifies formaldehyde as carcinogenic to humans (Group 1), based on sufficient evidence in humans and in experimental animals. Manyfold in vitro studies clearly indicated that formaldehyde can induce genotoxic effects in proliferating cultured mammalian cells. Furthermore, some in vivo studies have found changes in epithelial cells and in peripheral blood lymphocytes related to formaldehyde exposure. METHODS: A study was carried out in Portugal, using 80 workers occupationally exposed to formaldehyde vapours: 30 workers from formaldehyde and formaldehyde-based resins production factory and 50 from 10 pathology and anatomy laboratories. A control group of 85 non-exposed subjects was considered. Exposure assessment was performed by applying simultaneously two techniques of air monitoring: NIOSH Method 2541 and Photo Ionization Detection equipment with simultaneously video recording. Evaluation of genotoxic effects was performed by application of micronucleus test in exfoliated epithelial cells from buccal mucosa and peripheral blood lymphocytes. RESULTS: Time-weighted average concentrations not exceeded the reference value (0.75 ppm) in the two occupational settings studied. Ceiling concentrations, on the other hand, were higher than reference value (0.3 ppm) in both. The frequency of micronucleus in peripheral blood lymphocytes and in epithelial cells was significantly higher in both exposed groups than in the control group (p<0.001). Moreover, the frequency of micronucleus in peripheral blood lymphocytes was significantly higher in the laboratories group than in the factory workers (p < 0.05). A moderate positive correlation was found between duration of occupational exposure to formaldehyde (years of exposure) and micronucleus frequency in peripheral blood lymphocytes (r=0.401; p<0.001) and in epithelial cells (r=0.209; p < 0.01). CONCLUSIONS: The population studied is exposed to high peak concentrations of formaldehyde with a long-term exposure. These two aspects, cumulatively, can be the cause of the observed genotoxic endpoint effects. The association of these cytogenetic effects with formaldehyde exposure gives important information to risk assessment process and may also be used to assess health risks for exposed workers.

Efectos genotóxicos e inmunotóxicos de la exposición laboral al plomo / Genotoxic and immunotoxic of occupational exposure to lead

Objetivo. Evaluar los efectos genotóxicos e inmunotóxicos asociados a la exposición laboral al plomo.Métodos. Se ha realizado el ensayo de mutación en el receptor de las células T (TCR) y se han determinado las variacionesen los porcentajes de diferentes subpoblaciones linfocitarias y en las concentraciones de ciertas citoquinas circulantesen plasma sanguíneo mediante citometría de fl ujo en 30 trabajadores expuestos procedentes de 2 empresas y en 30 trabajadoresno expuestos como grupo control.Resultados: Los individuos expuestos mostraron frecuencias de mutación signifi cativamente mayores que los controles(media±error estándar: 20,88±3,58 vs. 12,98±2,88), independientemente de su empresa de procedencia, así como menorporcentaje de linfocitos CD8+ (%medio±error estándar: 31,97±1,70 vs. 36,70±1,30), descenso que sólo mantuvo signifi caciónen una de las empresas. Las concentraciones de las citoquinas analizadas fueron en general mayores en los expuestosque en los controles, siendo signifi cativo el incremento para IL-2 (media±error estándar: 1,09±0,26 vs. 0,25±0,17 pg/ml)e IL-10 (media±error estándar: 2,88±1,14 vs. 0,58±0,23 pg/ml), con diferencias entre empresas. Los efectos de la exposiciónen cuanto a frecuencia de mutación y concentraciones de IL-2 e IL-10 fueron mayores en los individuos no fumadores,apuntando a una menor susceptibilidad de los fumadores posiblemente como consecuencia de la potenciación de los mecanismosde reparación por el contacto crónico con el humo del tabaco.Conclusiones. Los resultados indican que la exposición laboral a plomo induce mutagenicidad y alteraciones en parámetrosinmunológicos, sugiriendo la necesidad de aplicación de medidas para la eliminación o disminución de los nivelesde plomo en los lugares de trabajo

Objective. To evaluate genotoxic and immunotoxic effects associated with occupational exposure to lead.Methods. A T-cell receptor (TCR) mutation assay was performed, and variations in the percentages of different lymphocytesubpopulations and in the concentrations of certain plasma circulating cytokines determined by fl ow cytometry in30 exposed individuals from 2 factories and 30 controls.Results. Exposed individuals showed signifi cantly higher levels of mutation frequency than controls (mean±standard error:20.88±3.58 vs. 12.98±2.88), regardless of their factory; the percentage of CD8+ lymphocytes was also lower (mean%±standard error: 31.97±1.70 vs. 36.70±1.30), although statistical signifi cance was observed in only one factory. Concentrations ofanalysed cytokines were generally higher among exposed individuals than controls. The increase was signifi cant for IL-2(mean±standard error: 1.09±0.26 vs. 0.25±0.17) and IL-10 (mean±standard error: 2.88±1.14 vs. 0.58±0.23), with differencesbetween factories. Exposure effects regarding mutation frequency and IL-2 and IL-10 concentrations were greater amongnonsmokers, suggesting a lower susceptibility of smokers as a consequence of strengthening of repair mechanisms throughchronic contact with tobacco smoke.Conclusions. Occupational exposure to lead induces mutagenicity and alterations in immunological parameters, suggestingthe need to apply measures for the elimination or decrease of lead levels in workplaces