Exposure to methyl methacrylate and its subjective symptoms among dental technicians, Tehran, Iran.

Exposure to methyl methacrylate (MMA), total dust and health symptoms were investigated in 20 dental laboratories located in Tehran, Iran. Time-weighted average (TWA) of MMA and peak concentrations were determined, using XAD-2 tubes followed by GC-FID analysis. Total dusts were evaluated gravimetrically. Health symptoms were asked using a questionnaire. TWA for technicians with direct and indirect exposure to MMA were 327.28 +/- 79.42 and 282.9 +/- 41.84 mg/m3, respectively. Peak concentration of MMA for those technicians were 337.0 +/- 36.81 and 328.88 +/- 45.40 mg/m3, respectively. There were no significant differences between TWA of MMA and peak concentration in different weekly workdays; however, within-day variations were observed (P < .05). TWA of MMA and peak concentration correlation with the laboratory volume were 0.61-0.65. Dust exposure of technicians was 2.35 +/- 2.70 mg/m3. Cough and skin dryness were the common health symptoms. Smoking and asbestos exposure history were factors influencing cough prevalence (p < .05). It is concluded that the current Short-Term Exposure Limit (STEL) is not low enough to protect technicians against the adverse effects caused by MMA.     

Solid phase extraction for evaluation of occupational exposure to Pb (II) using XAD-4 sorbent prior to atomic absorption spectroscopy.

Lead is an important constituent widely used in different industrial processes. For evaluation of workers' exposure to trace toxic metal of Pb (II), solid-phase extraction (SPE) was optimized. SPE using mini columns filled with XAD-4 resin was developed with regard to sample pH, ligand concentration, loading flow rate, elution solvent, sample volume, elution volume, the amount of resins, and sample matrix interferences. Lead ions were retained on a solid sorbent and then eluted, followed by a simple determination of analytes with flame atomic absorption spectrometery. The obtained recoveries of metal ions were greater than 92%. This method was validated with 3 different pools of spiked urine samples; it showed a good reproducibility over 6 consecutive days as well as 6 within-day experiments. This optimized method can be considered successful in simplifying sample preparation for a trace residue analysis of lead in different matrices when evaluating occupational and environmental exposures is required.     

Detection of low-grade mosaicism in fetal cells isolated from maternal blood

Recovering and analysing fetal erythrocytes from maternal blood is being pursued for non-invasive prenatal genetic diagnosis. We report the observation of 46, XY/47, XXY mosaicism in fetal cells from a woman whose first-trimester chorionic villus sampling (CVS) initially showed only 46, XY. Only after exhaustive (500 cells) analysis were four XXY cells found in cultured villi.     

Mosaicism for trisomy 12: Four cases with varying outcomes

Trisomy 12 observed in chorionic villus sampling (CVS) may reflect generalized mosaicism or indicate mosaicism confined to only the placenta. In this report, four cases of trisomy 12 observed in CVS or cultured placental biopsies with varying outcomes are presented. Seven dinucleotide repeat polymorphisms for chromosome 12 were used to determine the chromosome 12 origins in the fetus or child and to delineate the mechanism(s) that gave rise to the trisomy. In two cases (cases A and C), the mosaicism was confined to the placenta, resulting in normal liveborns. Although, in one case, the molecular results suggested an apparent duplication of one paternal chromosome 12 in the placenta, normal biparental inheritance was found in the diploid fetal cell line in both cases. In two other cases (cases B and D), trisomy 12 was observed in both extraembryonic and fetal tissues. In one of these pregnancies, a child was born by Caesarean section at 37 weeks because of intrauterine growth retardation and oligohydramnios, and resulted in neonatal death. Molecular markers and fluorescence in situ hybridization (FISH) revealed low-level trisomy 12 mosaicism in the spleen. In the fourth case, fetal abnormalities were detected on ultrasound and low-level trisomy 12 mosaicism was observed in amniotic fluid cells using conventional cytogenetics and FISH. Molecular markers revealed a maternal meiosis I non-disjunction of chromosome 12 in DNA from a cultured placental biopsy. Although predicting the outcomes of pregnancies involving confined placental mosaicism remains difficult, molecular techniques are valuable tools for distinguishing uniparental from biparental disomy and mechanisms of mosaicism.     

Pulmonary Functions of Welders in Gas Transmission Pipelines in Iran

This study evaluated the influence of welding on pulmonary functions in welders. Spirometry tests were performed before and after work shift in 91 welders and 25 clerks (control group). We examined forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC ratio and forced expiratory flow 25%-75% (FEF 25–75). Significant differences were found for FVC and FEV1/FVC between welders and the control group in pre- and post-shift measurements (p < .001). In welders, smoking and nonsmoking habit had no significant effects on any pulmonary indices before or after shift. Work experience and fume concentrations also had no significant effects on the majority of spirometric indices (p > .05). Most welders had at least 1 of the respiratory symptoms. Significant differences were found between pre- and post-shift indices (as percentage of predicted values calculated with spirometer) and between the welders engaged in some welding tasks and the control group before work shift. This study documented work-related changes in pulmonary functions in the welders and marked drops in these functions without symptoms in some welders.     

Exposure to Methyl Methacrylate and Its Subjective Symptoms Among Dental Technicians,Tehran, Iran

Exposure to methyl methacrylate (MMA), total dust and health symptoms were investigated in 20 dental laboratories located in Tehran, Iran. Time-weighted average (TWA) of MMA and peak concentrations were determined, using XAD-2 tubes followed by GC-ID analysis. Total dusts were evaluated gravimetrically. Health symptoms were asked using a questionnaire. TWA for technicians with direct and indirect exposure to MMA were 327.28 ± 79.42 and 282.9 ± 41.84 mg/m³ , respectively. Peak concentration of MMA for those technicians were 337.0 ± 36.81 and 328.88 ± 45.40 mg/m³, respectively.

There were no significant differences between TWA of MMA and peak concentration in different weekly workdays; however, within-day variations were observed (P < .05).

TWA of MMA and peak concentration correlation with the laboratory volume were 0.61-0.65. Dust exposure of technicians was 2.35 ± 2.70 mg/m³. Cough and skin dryness were the common health symptoms. Smoking and asbestos exposure history were factors influencing cough prevalence (p < .05).

It is concluded that the current Short-Term Exposure Limit (STEL) is not low enough to protect technicians against the adverse effects caused by MMA.     

Devulcanization of Ground Tires by Different Strains of Bacteria: Optimization of Culture Condition by Taguchi Method

Biological devulcanization of ground tires (GTs) was evaluated by eleven different bacteria belonging to the genera Thiobacillus, Gordonia, Nocardia, Amycolaptopsis and Pseudomonas. The GTs were treated by each bacterium in a mineral medium and devulcanization was measured by increasing the sulfate of the medium and decreasing the sulfur of the GTs. The effects of incubation time (10 and 20 days) and the percent of ground tire in the medium (0.5 and 5 w/v %) on desulfurization were investigated. No significant changes were observed after 10 days of incubation. The total sulfur contents of all bio-treated GTs were decreased by 6–21% in 0.5% GTs after 20 days of incubation. While in 5% GTs, the total sulfur contents were mainly decreased using Thiobacillus ferroxidans DSMZ 583 and PTCC 1647 up to 27 and 15%, respectively. SEM photograph further indicated a good coherency interface between the bacteria and the GTs. Subsequently, Taguchi method was applied for the optimization of the culture condition of DSMZ 583. An L12 orthogonal array was performed by which the effects of eleven factors in two levels were evaluated. It was found that the amount and mesh size of GTs are the most important factors in biological devulcanization of ground tires.     

Psychosocial and Individual Characteristics and Musculoskeletal Complaints Among Clinical Laboratory Workers

Musculoskeletal disorders (MSDs) are an important health problem among healthcare workers, including clinical laboratory ones. The aim of the present study was to investigate the prevalence of MSDs and individual and psychosocial risk factors among clinical laboratory workers. A cross-sectional study was carried out among 156 workers of 30 clinical laboratories in 3 towns of Iran. The Nordic questionnaire with individual and psychosocial risk factors was used to collect data. Multiple logistic regression analysis was performed. The prevalence of reported MSDs among the study population was 72.4% in the past 12 months. The most prevalent MSDs were pain in the lower back and neck; 42.7% and 33.3%, respectively. Significant relations were found between MSDs and age, gender, heavy work at home and job control (p < .05). MSDs among laboratory workers were high and associated with age, gender, heavy work at home and job control. More research into measuring these factors and workplace physical demands is suggested.     

Decision support system for monitoring environmental-human interactions

The specific aim of this study is to investigate popular attitudes toward trees. The paper is involved the understanding of biophilia tendencies with respect to people's views in an urban area. Biophilia is considered as the idea insisting on the dependency of human identity on his relationship with nature. The biophilia fundamental tendencies were explored to establish a biological framework for valuing and affiliating the natural world. Accordingly, the nine tendencies i.e. utilitarian, naturalistic, ecologistic-scientific, aesthetic, symbolic, humanistic, moralistic, dominionistic, and negativistic were investigate to find out how people relate to the nature especially trees. The investigation was based on a quantitative interview which was applied to the public population in the Liverpool urban parks. Data collected from the designed questionnaire was followed by analysis of the data to identify people's attitudes towards trees. The results indicated how important the physical appeal and beauty of trees was for the people and also showed the people's emotional attachments to trees. Furthermore, a decision support model was proposed to evaluate human instincts and preferences in relation to their surrounding areas using the Analytical Hierarchical Process (AHP). The proposed model composed the environmental factors and the biophilia tendencies as the criteria of evaluating environmental-human interactions. A case study was then conducted in Liverpool parks to examine theses interactions. The data gathered was used as the input to the AHP model for the attribute analysis. The AHP model would enable environment managers to compose the relevant information via a link between human feelings about urban trees, and environmental factors for monitoring purposes and performance analysis.