33 e-Letters

published between 2010 and 2013

  • Authors' reply to "Three interpretations of an ecological study
    Frank de Vocht

    We thank Dr Idrovo for his thoughts on our paper (1) regarding multilevel approaches to ecological studies (2). We agree with Dr Idrovo that incorporating different levels of aggregation to explore the impact of macro-determinants, or "cultural determinants", would be useful and could, in theory, illuminate important factors beyond causal hypothecation at the individual-level. In our study, however, we were unable to ful...

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  • Obliterative bronchiolitis in workers laying up fiberglass-reinforced plastics with polyester resin and methylethyl ketone peroxide catalyst.
    Yue Leon Guo

    Cullilinan et al [1] reported six obliterative bronchiolitis (OB) cases with plausible correlation with fiberglass-reinforced plastics (FRP) fabrication. Five of them were boat builders and one worked for a cooling- tower manufacturer. Due to the complexity of the FRP-related boat building processes, the exact agent(s) and process causing OB were difficult to determine. The cooling-tower manufacturing had a simpler manufact...

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  • Three interpretations of an ecological study
    Alvaro J. Idrovo

    The very interesting article by de Vocht et al (1) is a good opportunity to discuss possible interpretations of results obtained in ecological studies. The study included 165 nations as observations and found an association between mobile/cellular telecommunications (per 100 people) and brain cancer (national age-adjusted incidence rates). Although in this case authors were interested in the generation of individual-level...

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  • Re:The effect of low cadmium exposure on renal biomarkers
    Ramona Hambach

    The authors want to thank Prof. Dr. Kawada for his interest in our manuscript entitled 'Adverse effects of low occupational cadmium exposure on renal and oxidative stress biomarkers in solderers' [1]. Prof. Kawada recommends performing the multiple linear regression analysis without adjusting for pack-years of smoking. It is known that smoking is a major source of cadmium exposure [2, 3]. However, we want to underline th...

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  • Low solar ultraviolet-B irradiance and serum 25-hydroxyvitamin D levels likely explain the link between nightshift work and ovarian cancer
    William B. Grant

    The finding that nightshift work is linked to increased risk of ovarian cancer1 is one of a long series of studies finding that nightshift work is associated with increased risk of cancer [e.g., Ref. 2]. While reduced production of melatonin is a possible explanation, a better explanation is that since those on night shift sleep during daytime, they spend less time in the sun when they could be making vitamin D. Solar ul...

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  • Re:Environmental tobacco smoke and severe dementia syndromes
    Ruoling Chen

    In Reply,

    Professor Kawada [1] commented on our use of Cox regression for the analysis of cross-sectional data. [2] Although logistic regression is often used to compute a prevalence odds ratio (POR) in cross-sectional studies as an estimate of relative risk (RR), when the outcome is not rare this overestimates the RR, sometimes changing the study conclusion. Cox regression has been suggested instead to estima...

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  • Environmental tobacco smoke and severe dementia syndromes
    Tomoyuki Kawada

    Chen et al [1] reported the positive association between environmental tobacco smoke (ETS) and severe dementia syndromes. They mentioned that Cox regression model was applied to detect statistical significance.

    I have two queries on their study. First, they conducted cross- sectional study and Cox regression analysis was applied to detect relative risk by adjusting several confounders. They described the methodol...

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  • The effect of low cadmium exposure on renal biomarkers
    Tomoyuki Kawada

    Hambach et al [1] have published cross-sectional study on the associations between cadmium (Cd) exposure and renal or oxidative stress biomarkers in 36 solderers. They adopted multiple regression analysis to detect statistical significance with adjustment of age and pack-years of smoking. In contrast, there is a significant relationship between low levels of Cd exposure and N-acetyl-beta-D-glucosaminidase (NAG) [2,3], w...

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  • Blood lead levels in pregnant women in Nigeria: a cause for great concern
    Caroline M. Taylor

    We read the article by Njoku and Orisakwe comparing blood lead levels (BLL) in rural and urban pregnant women in Eastern Nigeria with great interest [1]. The authors found that BLL were substantially higher in rural areas than urban areas (135+/-160 vs 77+/-100 ug/dl). This in itself is an important finding: it may reflect a stronger reliance on locally grown foodstuffs in rural areas, combined with the effect of lead expo...

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  • Cadmium, arsenic and lung cancer: A complete picture?
    Tom Sorahan

    The Editor Occupational and Environmental Medicine

    14th September, 2012

    Cadmium, arsenic and lung cancer: A complete picture?

    Were the occupational lung cancers among former employees at the cadmium recovery plant located near Denver, CO, USA due to cadmium exposures, arsenic exposures or both? One of us recently suggested that a "simultaneous analysis of lung cancer risks in relation to both...

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