Total versus inhalable sampler comparison study for the determination of asphalt fume exposures within the road paving industry

Exposure to asphalt fumes has a threshold limit value (TLV of 0.5 mg m(-3) (benzene extractable inhalable particulate) as recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). This reflects a recent change (2000) whereby two variables are different from the previous recommendation. First is a 10-fold reduction in quantity from 5 mg m(-3) to 0.5 mg m(-3). Secondly, the new TLV specifies the "inhalable" fraction as compared to what is presumed to be total particulate. To assess the impact of these changes, this study compares the differences between measurements of paving asphalt fume exposure in the field using an "inhalable" instrument versus the historically used 'total' sampler. Particle size is also examined to assist in the understanding of the aerodynamic collection differences as related to asphalt fumes and confounders. Results show that when exposures are limited to asphalt fumes, a 1:1 relationship exists between samplers, showing no statistically significant differences in benzene soluble matter (BSM). This means that for the asphalt fume ACGIH TLV, the 'total' 37-mm sampler is an equivalent method to the "inhalable" method, referred to as IOM (Institute of Occupational Medicine), and should be acceptable for use against the TLV. However, the study found that when confounders (dust or old asphalt millings) are present in the workplace, there can be significant differences between the two samplers' reported exposure. The ratio of IOM/Total was 1.37 for milling asphalt sites, 1.41 for asphalt paving over granular base, and 1.02 for asphalt over asphalt pavements.     

Risk assessment of water pollutants

The sources of toxic xenobiotics and different factors such as ecological diversity, differences in comparative anatomy, physiology and biochemistry, food chain variation, interrelationship within species and life span, etc., are considered during risk assessment of pollutants, and their impact on aquatic ecotoxicology is identified. A fugacity and multimedia compartment model is suggested, based on toxicodynamic (toxicity of the chemical) and toxicokinetic (metabolism of the chemical) considerations to predict and screen the behaviour of pollutants quantitatively in the aquatic environment. The significance of the risk analysis approach in anticipatory actions and regulation of pollution levels is discussed.     

Application of remote sensing to exposure monitoring

Although exposure assessments cannot be completed remotely, remote sensing techniques provide an invaluable adjunct in exposure monitoring programs. Exposure can be defined as the summation over time, in all media, of the amount of a pollutant available at the exchange boundaries of the receptor during a specified period. This paper describes a few remote monitoring techniques that provide direct measurement input into an exposure assessment and several that furnish quantitative or qualitative information leading to decisions regarding how to monitor, such that the source-exposure-dose relationships can be fully defined. Two general classes of remote sensing systems are included in this discussion-passive and active. Passive systems depend on a measurement of the energy reflected or emitted by a target and active systems use an energy source, e.g., a laser to perform the environmental interrogation. Airborne as well as ground-based remote monitoring measurements or systems are also considered in this paper.     

Immunity in children with exposure to environmental lead: II. Effects on humoral immunity

Lead has been found to depress the immune system in animal studies at levels far below those responsible for overt toxicity. Literature studies in animal systems most clearly showed an effect of lead on response to a specific immunogenic stimulus. Data are sparse concerning the effects of lead on the immune system in the human population at greatest risk for exposure-children up to six years of age. This portion of the Phase I study reports concentrations of IgG, IgM, IgA, and IgE, as well as antibody titers to the specific antigenic stimuli provided by the vaccines against diphtheria, tetanus, and Rubella. The study population consisted of a group of 193 children, ages 9 months to 6 years, who participate in the WIC (Women, Infants and Children) and Lead Poisoning Prevention Programs in the urban area of Springfield-Greene County Missouri. Blood lead levels ranged from 1 to 50 g dL^–1. Total Ig levels were determined and the data were analysed. No consistent significant differences were observed among the risk categories in the five age groups examined. A single Ig class in each of three age groups showed apparent significant differences among the various risk categories, but these differences were not correlated with blood lead. An analysis of specific antibody titers to diphtheria, tetanus, and Rubella was performed. Regression analyses of current data in Phase I of this study suggest a detrimental effect of lead on the antibody titres to diphtheria and Rubella.     

Transformation of Organic Matter of the Larch Forest Soils in the Northern Taiga of Nizhne-Tungusskoe Plateau, Central Siberia

The evaluation of biospheric role of the boreal forests in the accumulation of carbon is connected with the evaluation of organic matter (OM) pool in soils. The research sites were larch forests, they are situated on Nizhne-Tungusskoe Plateau. Larch forests of feather-moss and lichen types (110 and 380 years old) were formed on 'ochric podbur' soils. Litter stocks are 3.5–4.5 kg m^{− 2} with thickness 10–25 cm. Cryomezomorphic northern taiga soils contains 38–73 t (carbon) ha^{− 1}. Pool of fast mineralized OM has average value 38.1 t (carbon) ha^{− 1}, including 20.5 and 6.4 t (Carbon) ha^{− 1} of labile compounds on surface and in the soil, and 11.2 t (carbon) ha^{− 1} of mobile OM. Microbial mass reaches 1.78–3.47 t (carbon) ha^{− 1}, its proportion is 3.6–4.9% of the total OM carbon. Zoomass of feather-moss larch forest is 0.20–0.61 * 10^{− 2}, in lichen larch forest −0.01–0.07 * 10^{− 2} t (carbon) ha^{− 1}. A pool of resistant to biological decomposition and bonded to mineral soil matrix OM is 17.7 t (carbon) ha^{− 1} and it varies from 18.6 to 29.0 in feather-moss larch forest, and from 6.4 to 17.0 t (carbon) ha^{− 1} in lichen larch forest. Two-years field experiment has been performed to determine transformation rates of various plant litter fractions and to clarify the role of soil biota in these processes. The results showed participation of all biota groups in the decomposition of plant residues caused weight loss of larch-needles and root mortmass. Isolation of organic matter from all-size invertebrate groups leads to some decrease of decomposition activity.     

Zur Photochemie in Adsorptionsschichten

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