Polonium-210 and lead-210 in the terrestrial environment: a historical review

The radionuclides ²¹⁰Po and ²¹⁰Pb widely present in the terrestrial environment are the final long-lived radionuclides in the decay of ²³⁸U in the earth’s crust. Their presence in the atmosphere is due to the decay of ²²²Rn diffusing from the ground. The range of activity concentrations in ground level air for ²¹⁰Po is 0.03-0.3 Bq m⁻³ and for ²¹⁰Pb 0.2-1.5 Bq m⁻³.In drinking water from private wells the activity concentration of ²¹⁰Po is in the order of 7-48 mBq l⁻¹ and for ²¹⁰Pb around 11-40 mBq l⁻¹. From water works, however, the activity concentration for both ²¹⁰Po and ²¹⁰Pb is only in the order of 3 mBq l⁻¹.Mosses, lichens and peat have a high efficiency in capturing ²¹⁰Po and ²¹⁰Pb from atmospheric fallout and exhibit an inventory of both ²¹⁰Po and ²¹⁰Pb in the order of 0.5-5 kBq m⁻² in mosses and in lichens around 0.6 kBq m⁻². The activity concentrations in lichens lies around 250 Bq kg⁻¹, dry mass.Reindeer and caribou graze lichen which results in an activity concentration of ²¹⁰Po and ²¹⁰Pb of about 1-15 Bq kg⁻¹ in meat from these animals. The food chain lichen-reindeer or caribou, and Man constitutes a unique model for studying the uptake and retention of ²¹⁰Po and ²¹⁰Pb in humans. The effective annual dose due to ²¹⁰Po and ²¹⁰Pb in people with high consumption of reindeer/caribou meat is estimated to be around 260 and 132 μSv a⁻¹ respectively.In soils, ²¹⁰Po is adsorbed to clay and organic colloids and the activity concentration varies with soil type and also correlates with the amount of atmospheric precipitation. The average activity concentration levels of ²¹⁰Po in various soils are in the range of 20-240 Bq kg⁻¹.Plants become contaminated with radioactive nuclides both by absorption from the soil (supported Po) and by deposition of radioactive fallout on the plants directly (unsupported Po). In fresh leafy plants the level of ²¹⁰Po is particularly high as the result of the direct deposition of ²²²Rn daughters from atmospheric deposition. Tobacco is a terrestrial product with high activity concentrations of ²¹⁰Po and ²¹⁰Pb. The overall average activity concentration of ²¹⁰Po is 13 ± 2 Bq kg⁻¹. It is rather constant over time and by geographical origin.The average median daily dietary intakes of ²¹⁰Po and ²¹⁰Pb for the adult world population was estimated to 160 mBq day⁻¹ and 110 mBq day⁻¹, corresponding to annual effective doses of 70 μSv a⁻¹ and 28 μSv a⁻¹, respectively. The dietary intakes of ²¹⁰Po and ²¹⁰Pb from vegetarian food was estimated to only 70 mBq day⁻¹ and 40 mBq day⁻¹ corresponding to annual effective doses of 30.6 μSv a⁻¹ and 10 μSv a⁻¹, respectively. Since the activity concentration of ²¹⁰Po and ²¹⁰Pb in seafood is significantly higher than in vegetarian food the effective dose to populations consuming a lot of seafood might be 5-15 fold higher.     

Non-thermal effects of EMF upon the mammalian brain: the Lund experience

The environment in which biology exists has dramatically changed during the last decades. Life was formed during billions of years, exposed to, and shaped by the original physical forces such as gravitation, cosmic irradiation and the terrestrial magnetism. The existing organisms are created to function in harmony with these forces. However, in the late 19th century mankind introduced the use of electricity and during the very last decades, microwaves of the modern communication society spread around the world. Today one third of the world’s population is owner of the microwave-producing mobile phones. The question is: to what extent are living organisms affected by these ubiquitous radio frequency fields? Since 1988 our group has studied the effects upon the mammalian blood-brain barrier (BBB) by non-thermal radio frequency electromagnetic fields (RF-EMF). These have been revealed to cause significantly increased leakage of albumin through the BBB of exposed rats as compared to non-exposed animals—in a total series of about two thousand animals. One remarkable observation is the fact that the lowest energy levels give rise to the most pronounced albumin leakage. If mobile communication, even at extremely low energy levels, causes the users’ own albumin to leak out through the BBB, also other unwanted and toxic molecules in the blood, may leak into the brain tissue and concentrate in and damage the neurons and glial cells of the brain. In later studies we have shown that a 2-h exposure to GSM 915 MHz at non-thermal levels, gives rise to significant neuronal damage, seen 28 and 50 days after the exposure. In our continued research, the non-thermal effects (histology, memory functions) of long-term exposure for 13 months are studied as well as the effects of short term GSM 1,800 MHz upon gene expression. Most of our findings support that living organisms are affected by the non-thermal radio frequency fields. Studies from other laboratories in some cases find effects, while in other cases effects are not seen. Our conclusion is that all researchers involved in this field have the obligation to intensify this research in order to reduce, or avoid, the possible negative effects of the man made microwaves!     

Can NO(2) be used to indicate ambient and personal levels of benzene and 1,3-butadiene in air?

The aim of this study was to investigate the relation between two toxic volatile organic compounds, 1,3-butadiene and benzene, and a commonly used indicator of vehicle exhaust fumes, NO(2). This was to see if NO(2) can be used to indicate personal exposure to carcinogenic substances or at least estimate ambient levels measured at a stationary point. During the winter of 2001, 40 randomly selected persons living in the City of Umea (in the north of Sweden) were recruited to the study. Personal measurements of 1,3-butadiene, benzene and NO(2) were performed for one week, and were repeated for 20 of the 40 participants. Additional information was gathered using a diary kept by each participant. During the same time period weekly stationary measurements were performed at one urban background station and one street station in the city centre. The results from the personal measurements showed a negligible association of NO(2) with 1,3-butadiene (r= 0.06) as well as with benzene (r= 0.10), while the correlation coefficient between 1,3-butadiene and benzene was high and significant (r= 0.67). In contrast to the personal measurements, the stationary measurements showed strong relations between 1,3-butadiene, benzene and NO(2) both within and in-between the street and urban background station. This study supports NO(2) as a potential indicator for 1,3-butadiene and benzene levels in streets or urban background air, while the weak relations found for the personal measurements do not support the use of NO(2) as an indicator for personal 1,3-butadiene and benzene exposure.     

Comparative health impact assessment of local and regional particulate air pollutants in Scandinavia

The ongoing program Clean Air for Europe (CAFE) is an initiative from the EU Commission to establish a coordinated effort to reach better air quality in the EU. The focus is on particulate matter as it has been shown to have large impact on human health. CAFE requested that WHO make a review of the latest findings on air pollutants and health to facilitate assessments of the different air pollutants and their health effects. The WHO review project on health aspects of air pollution in Europe confirmed that exposure to particulate matter (PM), despite the lower levels we face today, still poses a significant risk to human health. Using the recommended uniform risk coefficients for health impact assessment of PM, regardless of sources, premature mortality related to long-range transported anthropogenic particles has been estimated to be about 3500 deaths per year for the Swedish population, corresponding to a reduction in life expectancy of up to about seven months. The influence of local sources is more difficult to estimate due to large uncertainties when linking available risk coefficients to exposure data, but the estimates indicate about 1800 deaths brought forward each year with a life expectancy reduction of about 2-3 months. However, some sectors of the population are exposed to quite high locally induced concentrations and are likely to suffer excessive reductions in life expectancy. Since the literature increasingly supports assumptions that combustion related particles are associated with higher relative risks, further studies may shift the focus for abatement strategies. CAFE sets out to establish a general cost effective abatement strategy for atmospheric particles. Our results, based on studies of background exposure, show that long-range transported sulfate rich particles dominate the health effects of PM in Sweden. The same results would be found for the whole of Scandinavia and many countries influenced by transboundary air pollution. However, several health studies, including epidemiological studies with a finer spatial resolution, indicate that engine exhaust particles are more damaging to health than other particles. These contradictory findings must be understood and source specific risk estimates have to be established by expert bodies, otherwise it will not be possible to find the most cost effective abatement strategy for Europe. We are not happy with today's situation where every strategy to reduce PM concentrations is estimated to have the same impact per unit change in the mass concentration. Obviously there is a striking need to introduce more specific exposure variables and a higher geographical resolution in epidemiology as well as in health impact assessments.     

Past,current and future Swedish freshwater monitoring from an authority perspective

The synthesis of the BONUS+ research is introduced. The HELCOM Baltic Sea Action Plan is examined as a case to illustrate the potentials and challenges in building the science–policymaking interface on a macroregional level. The projects address environmental challenges in the Baltic Sea as defined by the Baltic Sea Action Plan, or consider the environmental governance and decision making within the Baltic Sea context in general. Eutrophication, biodiversity, hazardous substances, maritime activities, and the environment governance are addressed, as are crosscutting issues, such as the impact of climate change, maritime spatial planning and impacts of future development on ecosystem services. The projects contributed to relevant policy developments: 37 consultations carried out at EU level, 49 modifications to policy documents and action plans, 153 suggestions for the efficacy of pertinent public policies and governance, and in 570 occasions, scientists working in BONUS+ projects served as members or observers in scientific and stakeholder committees.     

Influence of hydropower dams on the composition of the suspended and riverbank sediments in the Danube

Large hydropower dams have major impacts on flow regime, sediment transport and the characteristics of water and sediment in downstream rivers. The Gabcikovo and Iron Gate dams divide the studied Danube transect (rkm 1895-795) into three parts. In the Gabcikovo Reservoir (length of 40km) only a part of the incoming suspended sediments were deposited. Contrary to this, in the much larger Iron Gate backwater zone and reservoir (length of 310km) all riverine suspended sediments were deposited within the reservoir. Subsequently, suspended sediments were transported by tributaries into the Iron Gate backwater zone. Here they were modified by fractional sedimentation before they transgressed downstream via the dams. Compared with undammed Danube sections, Iron Gate reservoir sediment and suspended matter showed higher clay contents and different K/Ga and Metal/Ga ratios. These findings emphasize the importance of reservoir-river sediment-fractionation.