An outlook on Dutch road safety in 2020; future developments of exposure,crashes and policy

This paper discusses the method used for an outlook on road safety in the Netherlands until 2020. The objectives of the outlook are to judge the feasibility of the Dutch road safety policy targets and to estimate the effects in 2020 of new measures. The outlook consists of baseline forecasts assuming the unchanged continuation of the effect of current road safety policy as a starting point, and the effect of new measures on top of that. We used four different mobility scenarios, derived from a comprehensive study about the macro-economic development of Dutch society until 2040. In the mobility scenario with the largest growth it appeared doubtful whether the policy targets of that time for the maximum number of fatalities in 2020 (580) can be achieved. An extensive inventory of new measures after 2010 produced five already intended new measures, the effects of which were estimated. The results show that the target of maximum 580 fatalities in 2020 can probably be met. The recently adjusted policy target of 500 fatalities in 2020 is also feasible if additional new measures are taken.     

Relationships between street characteristics and perceived attractiveness for walking reported by elderly people

Walking is important for the health of elderly people. Previous studies have found a relationship between neighbourhood characteristics, physical activity and related health aspects. The multivariate linear regression model presented here describes the relationships between the perceived attractiveness of streets for walking along and (physical) street characteristics. Two hundred and eighty-eight independently living elderly people (between 55 and 80 years old) participated in the study. Street characteristics were assessed along homogeneous street subsections defined as ‘links’. Positively related to perceived attractiveness of links were the following street characteristics: slopes and/or stairs, zebra crossings, trees along the route, front gardens, bus and tram stops, shops, business buildings, catering establishments, passing through parks or the city centre, and traffic volume. Litter on the street, high-rise buildings, and neighbourhood density of dwellings were negatively related to perceived link attractiveness. Overall, the results suggest that three main aspects affect perceived attractiveness of streets for walking, namely tidiness of the street, its scenic value and the presence of activity or other people along the street. The results are discussed within the context of these three aspects.     

The accumulation of metals and toxic effects in Nereis virens exposed to pulverised fuel ash

The marine polychaete worm Nereis virens was used to study the bioaccumulation patterns of metal exposures with pulverised fuel ash (PFA). Juvenile N. virens were exposed for 12 weeks to sediments comprised of 100% PFA, 50% PFA-50% clean sand, a reference sediment (contaminated harbour-dredged material) and a clean sand control. Mortality after the first 4 weeks was high at 32–45% in the four sediments. However, this declined to a few percent during the following 8 weeks. Growth expressed as biomass (wet weight) was reduced in bout PFA treatments and the reference sediment. Heavy metal accumulation in the tissues of N. virens was characterised as follows: a group of elements showed negligible to low accumulation (Cd, Cr, Ni, and Zn), As and Cu wich showed a definite, but moderate accumulation: and finally Se, which showed a low accumulation rate, where an uptake equilibrium was not reached after 9 weeks. It is concluded that acute toxic effects did not occur but a population of N. virens inhabiting a PFA dumping site could be affected by high Se concentrations.     

Trace Metal Uptake By Pichia Spartinae, an Endosymbiotic Yeast in the Salt Marsh Cord Grass Spartina Alterniflora

The ascosporogenous marine yeast Pichia spartinae is a dominant endosymbiont of the marsh grass Spartina alterniflora. Results of previous studies suggested that P. spartinae is involved in iron transport processes in the grass. of particular interest has been the mechanisms of metal uptake and metabolism by the yeast, and the ecological and plant biochemical significance of these processes. This investigation examined the uptake of iron and other metals (Zn, Cu, Cd, Ni, Pb, Cr) by P. spartinae, and provides data on possible mechanisms of this activity. the results suggest a) the yeast can assimilate divalent and trivalent forms of inorganic iron, as well as large organic-Fe(III) complexes, b) the uptake of inorganic trivalent iron under soluble iron-deficient conditions proceeded by a different mechanism than that of soluble Fe(II), with intracellular loadings of iron much increased under the former conditions; c) trivalent iron uptake is not mediated by hydroxamate siderophores at levels detectable by sensitive screening assays; d) the assimilation of some trace metals (Cu, Zn, Cd, Ni) is likely to be mediated by low molecular weight cysteine rich proteins, possibly metallothionein, and; e) siderophores from other fungi can provide iron for P. spartinae. the iron assimilation data suggested that multiple mechanisms are involved, and are influenced by the concentration and speciation of iron in the system. in general, iron assimilation mechanisms are comparable to those described for closely related yeasts, such as Saccharomyces cerevisiae. Among other things, these results indicated that future studies of trace metal mobilization and plant assimilation in salt marsh ecosystems must account for the activities of microbial symbionts associated with the plants.     

Sex-specific energy requirements in nestlings of an extremely sexually size dimorphic bird, the European sparrowhawk (Accipiter nisus)

Allocation of parental investment is predicted to be equal at the population level between both sexes of offspring, and should lead to sex ratio biases in species that exhibit a sex-difference in parental care. Sex-differences in parental care are rarely quantified. We measured daily energy expenditure in free-living nestlings of the extremely sexually size dimorphic European sparrowhawk (Accipiter nisus), using the doubly labelled water method. These data were combined with measured growth characteristics to estimate daily and total metabolised energy intake of male and female young during the nestling stage. Females reached an asymptotic body mass 1.6 times higher than males. This resulted in a total metabolised energy an estimated 1.4 times higher for the nestling stage. Furthermore, we observed a decline in daily metabolised energy with an increase in brood size, which was significantly stronger for females than for males. These results are discussed in the context of Fishers equal allocation theory. Empirical evidence of a sex ratio bias at the end of parental care, with an overall excess of males, is lacking in this species. Consequently, our data do not support the idea of equal allocation between the sexes. The observed sex difference in daily metabolised energy in response to brood size may give scope for sex ratio bias at the level of the individual brood.     

An integrated assessment of estrogenic contamination and biological effects in the aquatic environment of The Netherlands

An extensive study was carried out in the Netherlands on the occurrence of a number of estrogenic compounds in surface water, sediment, biota, wastewater, rainwater and on the associated effects in fish. Compounds investigated included natural and synthetic hormones, phthalates, alkylphenol(ethoxylate)s and bisphenol-A. The results showed that almost all selected (xeno-)estrogens were present at low concentrations in the aquatic environment. Locally, they were found at higher levels. Hormones and nonylphenol(ethoxylate)s were present in concentrations that are reportedly high enough to cause estrogenic effects in fish. Field surveys did not disclose significant estrogenic effects in male flounder (Platichthys flesus) in the open sea and in Dutch estuaries. Minor to moderate estrogenic effects were observed in bream (Abramis brama) in major inland surface waters such as lowland rivers and a harbor area. The prevalence of feminizing effects in male fish is largest in small regional surface waters that are strongly influenced by sources of potential hormone-disrupting compounds. High concentrations of plasma vitellogenin and an increased prevalence of ovotestes occurred in wild male bream in a small river receiving a considerable load of effluent from a large sewage treatment plant. After employing in vitro and in vivo bioassays, both in situ and in the laboratory, we conclude that in this case hormones (especially 17 alpha-ethynylestradiol) and possibly also nonylphenol(ethoxylate)s are primarily responsible for these effects.