Protection of the environment from ionising radiation in a regulatory context--an overview of the PROTECT coordinated action project.

The outcome of the PROTECT project (Protection of the Environment from Ionising Radiation in a Regulatory Context) is summarised, focusing on the protection goal and derivation of dose rates which may detrimentally affect wildlife populations. To carry out an impact assessment for radioactive substances, the estimated dose rates produced by assessment tools need to be compared with some form of criteria to judge the level of risk. To do this, appropriate protection goals need to be defined and associated predefined dose rate values, or benchmarks, derived and agreed upon. Previous approaches used to estimate dose rates at which there may be observable changes in populations or individuals are described and discussed, as are more recent derivations of screening benchmarks for use in regulatory frameworks. We have adopted guidance and procedures used for assessment and regulation of other chemical stressors to derive benchmarks. On the basis of consultation with many relevant experts, PROTECT has derived a benchmark screening dose rate, using data on largely reproductive effects to derive species sensitivity distributions, of 10 microGy h(-1) which can be used to identify situations which are below regulatory concern with a high degree of confidence.

Do estuaries pose a toxic contamination risk for wading birds?

The impact of potentially toxic chemicals on wildlife is commonly assessed by comparing the intake of the contaminant with the "no observable effects level" (NOAEL) of intake. It is known, however, that there are considerable uncertainties inherent in this method. This study presents a Monte-Carlo based model to assess the degree of risk posed to birds (dunlin, Calidris alpina) from important estuarine habitats, and to show the limitations of such risk assessments, particularly with regard to data availability. The model was applied to predict the uptake of metals (Hg, Pb) in this shorebird species in Poole Harbour and the Severn Estuary/Bristol Channel, UK, two internationally important shorebird habitats. The results show that in both areas, Pb and Hg concentrations may pose an ecologically relevant toxic risk to wading birds. For Pb, uncertainty in NOAEL values dominates the overall uncertainty. Use of lethal toxicity data (LD50/100) was investigated as a method for assessing sub-lethal impacts from Hg. It was found that this method led to a significant under-estimate of the potential impact of Hg contamination, compared with direct estimation of NOAEL.

Predicting body temperature and activity of adult Polyommatus icarus using neural network models under current and projected climate scenarios.

We use field observations in two geographic regions within the British Isles and regression and neural network models to examine the relationship between microhabitat use, thoracic temperatures and activity in a widespread lycaenid butterfly, Polyommatus icarus. We also make predictions for future activity under climate change scenarios. Individuals from a univoltine northern population initiated flight with significantly lower thoracic temperatures than individuals from a bivoltine southern population. Activity is dependent on body temperature and neural network models of body temperature are better at predicting body temperature than generalized linear models. Neural network models of activity with a sole input of predicted body temperature (using weather and microclimate variables) are good predictors of observed activity and were better predictors than generalized linear models. By modelling activity under climate change scenarios for 2080 we predict differences in activity in relation to both regional differences of climate change and differing body temperature requirements for activity in different populations. Under average conditions for low-emission scenarios there will be little change in the activity of individuals from central-southern Britain and a reduction in northwest Scotland from 2003 activity levels. Under high-emission scenarios, flight-dependent activity in northwest Scotland will increase the greatest, despite smaller predicted increases in temperature and decreases in cloud cover. We suggest that neural network models are an effective way of predicting future activity in changing climates for microhabitat-specialist butterflies and that regional differences in the thermoregulatory response of populations will have profound effects on how they respond to climate change.

A review of boron effects in the environment.

Boron (B) is a naturally occurring element that is found in the form of borates in the oceans, sedimentary rocks, coal, shale, and in some soils. Borates are released naturally into the atmosphere and aquatic environment from oceans, geothermal steams, and weathering of clay-rich sedimentary rocks. B is also released to a lesser extent from anthropogenic sources. B concentrations in air range from <0.5 to 80 ng/m3 with an average of 20 ng/m3, and in soils from 10 to 300 mg/kg with an average of 30 mg/kg. Concentrations of B in surface freshwaters are typically <0.1-0.5 mg/L; much higher concentrations are measured in a few areas, depending on the geochemical nature of the drainage catchment. B accumulates in both aquatic and terrestrial plants, but it does not appear to be biomagnified through the food chain. No observed effect concentrations (NOECs) for aquatic invertebrates tend to be in the range of 6-10 mg B/L with lower values of 1-2 mg/L for community studies. No effect concentrations for fish in natural waters are around 1 mg/L, although lower values have been recorded in reconstituted water. Comparing no effect concentrations with the general ambient environmental levels indicates that the risk to aquatic ecosystems from B is low. In a few B-rich areas, natural levels will be higher; however, there is some indication that organisms may be adapted to the local conditions. B is an essential micronutrient for higher plants with interspecies differences in the levels required for optimum growth. In general, there is a small concentration range between deficiency and toxicity; however, toxicity owing to excess B is much less common in the environment than B deficiency. Levels of B in aquatic plants growing in areas receiving B-rich runoff from irrigated fields are higher than dietary concentrations, which cause effects on the growth of young birds in the laboratory; however, the bioavailability in the field of such plant-accumulated B is uncertain.

Plasma corticosterone in wild starlings (Sturnus vulgaris) immediately following capture and in relation to body weight during the annual cycle.

Free-living starlings (Sturnus vulgaris) were caught by mist netting. Blood samples were taken from them between 20 sec and 4 min after capture and assayed for corticosterone. Before 1 min corticosterone levels were constant (10.3 nmol litre-1) but after 1 min they increased rapidly (27.0 +/- 3.6 nmol litre-1 min-1). Male and female free-living starlings were caught throughout the year with mist nets, and traps placed in nest boxes. Blood samples were taken within 1 min of capture and body weights recorded. Plasma corticosterone varied between 3 and 13 nmol litre-1. In both sexes the level was high during winter and through the breeding season. It fell to low levels during late summer and increased again during autumn. Body weight in both sexes was highest in midwinter and lowest in midsummer but there was no correlation between body weight and plasma corticosterone concentration.