Addressing Nonlinearity in the Exposure-Response Relationship for a Genotoxic Carcinogen: Cancer Potency Estimates for Ethylene Oxide

Ethylene oxide (EO) has been identified as a carcinogen in laboratory animals. Although the precise mechanism of action is not known, tumors in animals exposed to EO are presumed to result from its genotoxicity. The overall weight of evidence for carcinogenicity from a large body of epidemiological data in the published literature remains limited. There is some evidence for an association between EO exposure and lympho/hematopoietic cancer mortality. Of these cancers, the evidence provided by two large cohorts with the longest follow-up is most consistent for leukemia. Together with what is known about human leukemia and EO at the molecular level, there is a body of evidence that supports a plausible mode of action for EO as a potential leukemogen. Based on a consideration of the mode of action, the events leading from EO exposure to the development of leukemia (and therefore risk) are expected to be proportional to the square of the dose. In support of this hypothesis, a quadratic dose-response model provided the best overall fit to the epidemiology data in the range of observation. Cancer dose-response assessments based on human and animal data are presented using three different assumptions for extrapolating to low doses: (1) risk is linearly proportionate to dose; (2) there is no appreciable risk at low doses (margin-of-exposure or reference dose approach); and (3) risk below the point of departure continues to be proportionate to the square of the dose. The weight of evidence for EO supports the use of a nonlinear assessment. Therefore, exposures to concentrations below 37 microg/m3 are not likely to pose an appreciable risk of leukemia in human populations. However, if quantitative estimates of risk at low doses are desired and the mode of action for EO is considered, these risks are best quantified using the quadratic estimates of cancer potency, which are approximately 3.2- to 32-fold lower, using alternative points of departure, than the linear estimates of cancer potency for EO. An approach is described for linking the selection of an appropriate point of departure to the confidence in the proposed mode of action. Despite high confidence in the proposed mode of action, a small linear component for the dose-response relationship at low concentrations cannot be ruled out conclusively. Accordingly, a unit risk value of 4.5 x 10(-8) (microg/m3)(-1) was derived for EO, with a range of unit risk values of 1.4 x 10(-8) to 1.4 x 10(-7) (microg/m3)(-1) reflecting the uncertainty associated with a theoretical linear term at low concentrations.     

Integrated reporting: an exploratory study of French companies

The increasing complexity of the business world has led to growing demands for companies to provide information about their financial performance, their corporate governance and their contribution to developing sustainability. In addition, there are increasing needs for investors to obtain more information about the value creation process since financial reporting systems account imperfectly for most of intangible assets generated by companies. In this context, this article aims to determine if integrated reporting does effectively achieve the objective of reducing the information asymmetry. To answer this research question, a qualitative content analysis was conducted of the IR disclosed by the French companies in the period of 2013–16. The study reveals that information asymmetry is not reduced since companies mention only some capitals as inputs to their value creation process while almost entirely excluding natural capital. Moreover, companies disclose only positive information mainly about their financial capital, without mentioning any destruction of capital, especially not the natural one. Finally, from our findings, signals disclosed by these companies can be classified in three categories: intent signals composed of information about social and relational capital; camouflage signals composed of information about the reduction of the pollution without mentioning the pollution itself and need signals composed of information about dividends encouraging investors to maintain their financial support.

     

Racial Mistrust Among Immigrant Minority Students

This paper examines perception of racial mistrust held by minority students towards white teachers during middle school years. The investigation determined relationships between levels of racial mistrust and the length of time English-speaking West Indian and Haitian students lived in the United States. Results indicate 35 to 50% of the students perceived moderate or high levels of racial mistrust. While no statistically significant relationships were indicated during the 6th and 7th, or 8th grades towards the ending of the 9th grade positive and statistically significant relationships were indicated for English-speaking West Indian as well as Haitian students. In addition to risks of unfavorable levels of racial mistrust low academic achievements remained a concern for both groups. Implications for social work research and practice with immigrant students are addressed.     

The Older Sandwich Generation Across European Welfare Regimes: Demographic and Social Considerations

European Journal of Population - The lengthening of the amount of time adult children depend on their parents’ support and rising longevity have pushed scholars to devote increasing attention...