Stakeholders’ Perspective on Ecological Modeling in Environmental Risk Assessment of Pesticides: Challenges and Opportunities

The article closely examines the role of mechanistic effect models (e.g., population models) in the European environmental risk assessment (ERA) of pesticides. We studied perspectives of three stakeholder groups on population modeling in ERA of pesticides. Forty‐three in‐depth, semi‐structured interviews were conducted with stakeholders from regulatory authorities, industry, and academia all over Europe. The key informant approach was employed in recruiting our participants. They were first identified as key stakeholders in the field and then sampled by means of a purposive sampling, where each stakeholder identified as important by others was interviewed and asked to suggest another potential participant for our study. Our results show that participants, although having different institutional backgrounds often presented similar perspectives and concerns about modeling. Analysis of repeating ideas and keywords revealed that all stakeholders had very high and often contradicting expectations from models. Still, all three groups expected effect models to become integrated in future ERA of pesticides. Main hopes associated with effect models were to reduce the amount of expensive and complex testing and field monitoring, both at the product development stage, and as an aid to develop mitigation measures. Our analysis suggests that, although the needs of stakeholders often overlapped, subtle differences and lack of trust hinder the process of introducing mechanistic effect models into ERA.     

Economics of the firm and economic growth: a hybrid theoretical framework of analysis

Abstract

The main goal of this study is to achieve a critical discussion around the conceptualization of the firm and its role in the dynamic process of economic growth. By reviewing the theoretical matrix of the economics of the firm we go beyond the mainstream economics of the firm proposing a hybrid approach combining evolutionary and population ecology, which is likely to constitute a fruitful path for the conceptualization of the firm in the process of economic growth. Specifically, the analysis confronts the distinct theoretical perspectives around some imperative and controversial issues such as the nature of knowledge and learning and the cognitive capacities of economic agents within the firm. We argue that the economic understanding of growth and development of human societies will strongly benefit from a conceptualization of the firm capable of capturing the spirit of the Knightian firm. Overcoming the shortcomings of the mainstream growth models, which conceive firms as a black box, the proposed hybrid approach recalls the true nature of the firm as an organization. Issues related to the organizational arrangements that sustain the feasibility of productive activities and to the incentive contracts are also taken into account. Although acknowledging some recent important contributions within mainstream economic growth theory to adopt more realistic concepts of the firm, we believe that evolutionary and organizational population perspectives include crucial pointers in developing further research aimed at the construction of economic growth models based on a micro-economic perspective that is closer to the reality of firms.     

An Exposure Assessment of Methyl Mercury via Fish Consumption for the Japanese Population

The objective of this article was to propose an exposure assessment model to describe the relationship between fish consumption and body methyl mercury (MeHg) levels in the Japanese population. Individual MeHg intake was estimated by the summation of species-specific fish consumption multiplied by species-specific fish MeHg levels. The distribution of fish consumed by individuals and the MeHg level in each fish species were assigned based on published data from Japanese government institutions. The probability of MeHg intake for a population was accomplished through a Monte Carlo simulation by the random sampling of fish consumption and species-specific MeHg levels. Internal body MeHg levels in blood and hair were estimated using a one-compartment model. Overall, the mean value of MeHg intake for the Japanese population was estimated to be 6.76 μg/day or 0.14 μg/kg body weight per day (bw/day), while the mean value for the hair mercury level was 2.02 μg/g. Compared with the survey data that tabulated hair mercury levels in a cross-section of the Japanese population, the simulation results matched the hair mercury survey data very well for women, but somewhat underestimated for men and all of the population. This exposure assessment model is a useful attempt at further risk assessment with respect to a risk-benefit analysis.     

Relevance of Risk Predictions Derived from a Chronic Species Sensitivity Distribution with Cadmium to Aquatic Populations and Ecosystems

Criteria to protect aquatic life are intended to protect diverse ecosystems, but in practice are usually developed from compilations of single‐species toxicity tests using standard test organisms that were tested in laboratory environments. Species sensitivity distributions (SSDs) developed from these compilations are extrapolated to set aquatic ecosystem criteria. The protectiveness of the approach was critically reviewed with a chronic SSD for cadmium comprising 27 species within 21 genera. Within the data set, one genus had lower cadmium effects concentrations than the SSD fifth percentile‐based criterion, so in theory this genus, the amphipod Hyalella, could be lost or at least allowed some level of harm by this criteria approach. However, population matrix modeling projected only slightly increased extinction risks for a temperate Hyalella population under scenarios similar to the SSD fifth percentile criterion. The criterion value was further compared to cadmium effects concentrations in ecosystem experiments and field studies. Generally, few adverse effects were inferred from ecosystem experiments at concentrations less than the SSD fifth percentile criterion. Exceptions were behavioral impairments in simplified food web studies. No adverse effects were apparent in field studies under conditions that seldom exceeded the criterion. At concentrations greater than the SSD fifth percentile, the magnitudes of adverse effects in the field studies were roughly proportional to the laboratory‐based fraction of species with adverse effects in the SSD. Overall, the modeling and field validation comparisons of the chronic criterion values generally supported the relevance and protectiveness of the SSD fifth percentile approach with cadmium.     

Sequential confidence intervals for the number of cells in a multinomial population

A two-sided sequential confidence interval is suggested for the number of equally probable cells in a given multinomial population with prescribed width and confidence coefficient. We establish large-sample properties of the fixed-width confidence interval procedure using a normal approximation, and some comparisons are made. In addition, a simulation study is carried out in order to investigate the finite sample behaviour of the suggested sequential interval estimation procedure.     

Mortality following conjugal bereavement,Belgium 1991-96: The unexpected effect of education

This paper examines excess mortality following spousal bereavement by time since bereavement, sex, age, and education. The main hypothesis challenged is that higher education buffers the harmful effects of spousal loss. Using a log-rate model, death-rate ratios (widowed/married) are estimated for 49,849 and 126,746 Belgian widowers and widows and an equal number of non-bereaved controls matched to the bereaved on their socio-demographic characteristics. The hypothesis that the more educated suffer less excess mortality is not supported. Although higher educational levels are associated with lower mortality in general, they do not alleviate the effects of bereavement. On the contrary, in the period immediately following spousal loss, the more highly educated seem to have more, rather than less, excess mortality. Three possible arguments are suggested to account for this: education-related differences in the partner-relationship, structural differences in the availability of appropriate social support, and cultural differences in potential support networks.     

Effects of population policy and economic reform on the trend in fertility in Guangdong province,China, 1975–2005

An analysis of data mainly from China's 1990 and 2000 censuses and 2005 mini-census shows how fertility decline between 1975 and 2005 in the province of Guangdong has been influenced by both fertility policy and economic and social development. Guangdong's development since 1975 has been very rapid and has attracted huge numbers of migrants from other provinces. The analysis of the province's fertility trend from 1975 shows clearly the influence of fertility policy on the trend. The analysis also shows that economic development has brought about large changes in population composition by urban/rural residence, education, occupation, and migration status, which, together with large fertility differentials by these characteristics, have contributed substantially to Guangdong's fertility decline, in large part through changes in proportions currently married.     

RESEARCH NOTE Some evidence against the assumption that approval of family planning is associated with frequency of spouses' discussion of the subject

Much previous work on the relationship between respondent's reported frequency of discussion with spouse about family planning and correctness of reporting spouse's approval of family planning has led to the conclusion that discussion promotes approval. In this paper, data from the 1998 Kenya Demographic and Health Surveys are used to show that a focus on the relationship between frequency of discussion and correctness of reporting partner's disapproval of family planning leads to sceptical conclusions about the effects of discussion in improving knowledge of partner's attitude or in promoting approval.     

关于我国人口教育概念的重新认定

本文通过对我国人口教育发展历程的回顾 ,提出重新认定人口教育教学内容问题 ,并试图通过整合课程途径来实现这一目标     

浙江人口发展前景及战略选择

本文根据1990年"四普"资料和1995年1％人口抽样调查资料,在分析人口发展现状的基础上对浙江未来人口发展趋势进行了预测,并对浙江跨世纪的人口发展战略进行了探索,提出在保持适度低生育率、继续控制人口总量的前提下,宜谨慎地调整生育政策,以避免人口过于老化;根据浙江人口现状和'科教兴省'的战略思想,宜适时地将人口发展战略重点转移到提高人口素质上来。