Yah C.S.,National Institute of Occupational Health NIOH |
Iyuke S.E.,University of Witwatersrand |
Simate G.S.,University of Witwatersrand |
Unuabonah E.I.,Redeemers University |
And 3 more authors.
Journal of Materials Research | Year: 2011
This work reports the continuous and large-scale production of multiwalled carbon nanotubes (MWCNTs) from xylene/ferrocene in a swirled floating catalyst chemical vapor deposition reactor using argon as the carrier gas. The concentration of ferrocene used was 0.01 g/mL of xylene. In every run, 50-mL xylene gas was used together with xylene/ferrocene mixture injected into the reactor by means of a burette. The MWCNTs produced were characterized using the transmission electron microscopy (TEM) and Raman spectra. TEM analysis showed a poor production rate at 850 °C and a good production in the range of 900-1000 °C with optimal production rate at 950 °C. Furthermore, xylene/ferrocene mixture produced more MWCNTs at 950 °C with H:Ar (1:7) as the carrier gas. The diameters of the MWCNTs in the temperatures studied ranged from 15 to 95 nm with wall thicknesses between 0.5 and 0.8 nm. © 2011 Materials Research Society. Source
Veyhe A.S.,Health Science University |
Hofoss D.,Health Science University |
Hofoss D.,University of Oslo |
Hansen S.,Health Science University |
And 6 more authors.
International Journal of Hygiene and Environmental Health | Year: 2015
Background: Although predictors of contaminants in serum or whole blood are usually examined by chemical groups (e.g., POPs, toxic and/or essential elements; dietary sources), principal component analysis (PCA) permits consideration of both individual substances and combined variables. Objectives: Our study had two primary objectives: (i) Characterize the sources and predictors of a suite of eight PCBs, four organochlorine (OC) pesticides, five essential and five toxic elements in serum and/or whole blood of pregnant women recruited as part of the Mother-and-Child Contaminant Cohort Study conducted in Northern Norway (The MISA study); and (ii) determine the influence of personal and social characteristics on both dietary and contaminant factors. Methods: Recruitment and sampling started in May 2007 and continued for the next 31 months until December 2009. Blood/serum samples were collected during the 2nd trimester (mean: 18.2 weeks, range 9.0-36.0). A validated questionnaire was administered to obtain personal information. The samples were analysed by established laboratories employing verified methods and reference standards. PCA involved Varimax rotation, and significant predictors (p ≤. 0.05) in linear regression models were included in the multivariable linear regression analysis. Results: When considering all the contaminants, three prominent PCA axes stood out with prominent loadings of: all POPs; arsenic, selenium and mercury; and cadmium and lead. Respectively, in the multivariate models the following were predictors: maternal age, parity and consumption of freshwater fish and land-based wild animals; marine fish; cigarette smoking, dietary PCA axes reflecting consumption of grains and cereals, and food items involving hunting. PCA of only the POPs separated them into two axes that, in terms of recently published findings, could be understood to reflect longitudinal trends and their relative contributions to summed POPs. Conclusions: The linear combinations of variables generated by PCA identified prominent dietary sources of OC groups and of prominent toxic elements and highlighted the importance of maternal characteristics. © 2014 Elsevier GmbH. Source
Nigam S.K.,National Institute of Occupational Health NIOH |
Eurasian Journal of Medicine | Year: 2013
Objective: Betel leaf combined with areca nut is known as betel quid pan masala (PM), and tobacco with areca nut, catechu and lime is pan masala (PMT) blended with gulkhand. These narcotics are popular among young and old individuals. A prima facia chemical analysis and a toxicity assessment of PM in mice were conducted to study the relationship between longtime consumption of PM and health hazards. Materials and Methods: Chemical analysis of different types of PM was done employing HPLC, GLC, AAS, ES, TLC, GCMS and sequential extraction for PAH, pesticides, metals and minerals, electrolytes, drugs and xenobiotics. Ethanolic PM extracts were tested by IP and PO routes in inbred Swiss mice. Results: PAH, which are known xenobiotics for pre-cancerous lesions, were significantly high (p<0.01) in Rajaniganda and Pan Parag Zarda. Isomers of DDT and BHC, which principally act on nerves and muscles, were also high (p<0.01) in PM. The enhanced metal and mineral content of PM results in massive oral fibrosis. There is a high level of narcotics in PM, especially nicotine, a potentially cancerous agent in the gastrointestinal tract. Conclusion: Experimental studies with different extracts of plain and blended PM in mice fed for 16 and 90 days revealed no effect on blood and organ weights (kidney, heart, spleen and liver), but we did observe attenuated testis. However, in the bone marrow of the mice, chromosomes were most affected in the mice fed PM-Zarda blend for 3 months. The chromosomal abnormalities included ploidy, loss, breaks, gaps, deletions and exchanges in ring chromosomes. The PM caused sperm head anomalies (narrow, blunt, triangular and banana shapes), and the sperm were irregular, amorphous, tailless and rudimentary, with the maximum effect among the groups fed PM for 3 months. Significantly higher levels (p<0.01) of testis glycogen, cholesterol and protein were found. The group fed for 16 days showed no change in red blood corpuscles (RBC), white blood corpuscles (WBC), hemoglobin and erythrocyte sedimentation counts. Source
Hansen S.,University of Tromso |
Nieboer E.,University of Tromso |
Nieboer E.,McMaster University |
Sandanger T.M.,University of Tromso |
And 5 more authors.
Journal of Environmental Monitoring | Year: 2011
The objective of this study was to investigate changes in the levels of toxic and essential elements in maternal blood during pregnancy and subsequently. A subset of 211 pregnant women from the North Norwegian Mother-and-Child Study was included. Blood samples were collected during the 2 nd trimester (P1) and postpartum (day 3, P2; and 6 weeks, P3) in different regions of northern Norway, and were analyzed for a suite of 10 selected elements. The latter feature three general but distinct concentration patterns across the three collection periods, namely: progressive increase [Group 1: As, Cd (non-smokers only), Mn, Pb and Zn]; V-shaped, with a minimum at P2 [Group 2: Cd (smokers), Hg, Mo and Se]; and downward V, with a maximum at P2 [Group 3: Co and Cu]. These trends are interpreted in the context of underlying metabolic, hematological and physiological changes that occur in mothers, as well the biochemistry and accumulation preferences of these elements within the whole blood compartment and breast milk. Implications for biomonitoring strategies are discussed. In a multivariable analysis of the P1 data, fish consumption was a robust positive predictor for Hg (p < 0.02), As (p < 0.01) and Se (p ≤ 0.001) blood concentrations, multivitamin intake for Se (p < 0.001), and parity for Co (p < 0.002); age reached significance only for Hg (p < 0.001). An inverse association was observed between parity and Hg (p < 0.05). For the other elements, predictor patterns were not evident. © 2011 The Royal Society of Chemistry. Source
Casas M.,Center for Research in Environmental Epidemiology |
Casas M.,CIBER ISCIII |
Casas M.,University Pompeu Fabra |
Cordier S.,French Institute of Health and Medical Research |
And 49 more authors.
Scandinavian Journal of Work, Environment and Health | Year: 2015
Objectives We assessed whether maternal employment during pregnancy – overall and in selected occupational sectors – is associated with birth weight, small for gestational age (SGA), term low birth weight (LBW), length of gestation, and preterm delivery in a population-based birth cohort design. Methods We used data from >200 000 mother-child pairs enrolled in 13 European birth cohorts and compared employed versus non-employed women. Among employees, we defined groups of occupations representing the main sectors of employment for women where potential reproductive hazards are considered to be present. The comparison group comprised all other employed women not included in the occupational sector being assessed. We performed meta-analyses of cohort-specific estimates and explored heterogeneity. Results Employees had a lower risk of preterm delivery than non-employees [adjusted odds ratio (ORadj) 0.86, 95% confidence interval (95% CI) 0.81–0.91]. Working in most of the occupational sectors studied was not associated with adverse birth outcomes. Being employed as a nurse was associated with lower risk SGA infants (ORadj 0.91, 95% CI 0.84–0.99) whereas food industry workers had an increased risk of preterm delivery (ORadj 1.50, 95% CI 1.12–2.02). There was little evidence for heterogeneity between cohorts. Conclusions This study suggests that, overall, employment during pregnancy is associated with a reduction in the risk of preterm birth and that work in certain occupations may affect pregnancy outcomes. This exploratory study provides an important platform on which to base further prospective studies focused on the potential consequences of maternal occupational exposures during pregnancy on child development. © 2015, Nordic Association of Occupational Safety and Health. All rights reserved. Source