Objective: To investigate the association between long term residential exposure to road traffic and railway noise and risk of incident dementia. Design: Nationwide prospective register based cohort study. Setting: Denmark. Participants: 1 938 994 adults aged ≥60 years living in Denmark between 1 January 2004 and 31 December 2017. Main outcome measures: Incident cases of all cause dementia and dementia subtypes (Alzheimer’s disease, vascular dementia, and Parkinson’s disease related dementia), identified from national hospital and prescription registries. Results: The study population included 103 500 participants with incident dementia, and of those, 31 219 received a diagnosis of Alzheimer’s disease, 8664 of vascular dementia, and 2192 of Parkinson’s disease related dementia. Using Cox regression models, 10 year mean exposure to road traffic and railway noise at the most (L _den max) and least (L _den min) exposed façades of buildings were associated with a higher risk of all cause dementia. These associations showed a general pattern of higher hazard ratios with higher noise exposure, but with a levelling off or even small declines in risk at higher noise levels. In subtype analyses, both road traffic noise and railway noise were associated with a higher risk of Alzheimer’s disease, with hazard ratios of 1.16 (95% confidence interval 1.11 to 1.22) for road L _den max ≥65 dB compared with <45 dB, 1.27 (1.22 to 1.34) for road L _den min ≥55 dB compared with <40 dB, 1.16 (1.10 to 1.23) for railway L _den max ≥60 dB compared with <40 dB, and 1.24 (1.17 to 1.30) for railway L _den min ≥50 dB compared with <40 dB. Road traffic, but not railway, noise was associated with an increased risk of vascular dementia. Results indicated associations between road traffic L _den min and Parkinson’s disease related dementia. Conclusions: This nationwide cohort study found transportation noise to be associated with a higher risk of all cause dementia and dementia subtypes, especially Alzheimer’s disease.

Background: Internet has been broadly employed as a facilitator for epidemiological surveys, as a way to provide a more economical and practical alternative to traditional survey modes. A current trend in survey research is to combine Web-based surveys with other survey modes by offering the participant the possibility of choosing his/her preferred response method (i.e. mixed-mode approach). However, studies have also demonstrated that the use of different survey modes may produce different responses to the same questions, posing potential challenges on the use of mixed-mode approaches.Methods: In this paper, we have implemented a statistical comparison between mixed-mode survey responses collected via mail (i.e. paper) and Web methods obtained from a cross-sectional study in non-urban areas of Denmark. Responses provided by mail and Web participants were compared in terms of: 1) the impact of reminder letters in increasing response rates; 2) differences in socio-demographic characteristics between response groups; 3) changes on the likelihood of reporting health symptoms and negative attitudes towards environmental stressors. Comparisons were mainly performed by two sample t-test, Pearson’s Chi-squared test and multinomial logistic regression models.Results: Among 3104 contacted households, 1066 residents decided to participate on the study. Out of those, 971 selected to respond via mail, whereas 275 preferred the Web method. The majority of socio-demographic characteristics between these two groups of respondents were shown to be statistically different. The use of mailed surveys increased the likelihood of reporting health symptoms and negative attitudes towards environmental stressors, even after controlling for demographic characteristics. Furthermore, the use of reminder letters had a higher positive impact in increasing responses of Web surveys when compared to mail surveys.Conclusions: Our main findings suggest that the use of mail and Web surveys may produce different responses to the same questions posed to participants, but, at the same time, may reach different groups of respondents, given that the overall characteristics of both groups considerably differ. Therefore, the tradeoff between using mixed-mode survey as a way to increase response rate and obtaining undesirable measurement changes may be attentively considered in future survey studies.

Several studies have focused on the removal and recovery of precious metal ions from industrial wastewater due to their environmental and economic importance. Adsorption on bentonite clays has been shown to possess a high removal potential for several metal ions. We herein investigated the dynamic adsorption of silver using a fixed-bed column and a calcined bentonite clay called Verde-lodo as an adsorbent. A fluid dynamic study was performed to evaluate the adsorption system's metal-ion removal capacity (q_u and q_t), the mass transfer zone and the percentage of total removal according to different effluent's flow. Adsorption–desorption cycles were carried out using nitric acid as an eluent to evaluate the useful lifetime of the column. The breakthrough curves were fitted to the Bohart–Adams model (quasichemical). Moreover, the zeta potential was analyzed to explain the difference between the removal capacity obtained for the static and dynamic systems.