No abstract

Elimination rate constants (k2), biological half-lives (t(1/2)), and the time required to reach 95% of steady-state (t95) are reported for 46 individual polycyclic aromatic hydrocarbons (PAHs) including both parent and alkyl homologues, for the freshwater unionid mussel, Elliptio complanata. Elimination rate constants generally follow first-order kinetics and range from 0.04/day (d) for perylene to 0.26/d for 2,6-dimethylnapthalene, half-lives range from 2.6 to 16.5 d, and t95 values range from 11.3 to 71.3 d. These values compare well with other k2, t(1/2), and t95 values reported in the literature for PAHs and other classes of hydrophobic organic contaminants. A linear regression of k2 versus log Kow demonstrates dependence of PAH elimination on hydrophobicity, as measured by an r2 value of 0.83, and produces the following regression equation: k2 = -0.06 (log Kow) + 0.44. This study provides evidence that mussels experiencing different forms of physiological stress (e.g., handling stress and fungal or bacterial growth) can exhibit large variation in toxicokinetic parameters. These results are particularly relevant to the extrapolation of laboratory results to field situations.

Consorci Costa Brava is a public water utility created in 1971 responsible of the management of the water cycle in NE Spain. Reclaimed water is produced in 13 facilities which, over the years, have improved their performance and reliability. Operational protocols, online probes, quality-protection criteria and automatization have been instrumental to increase the safety of water reuse by both reducing the risk of failures in the key processes of the reclamation treatment, and by reducing the likelihood that water of insufficient quality could ever reach the end user. This degree of protection has been achieved after identifying the critical control points (CCPs) and the attention points (APs) of the reclamation treatments and also after establishing threshold safety levels for the essential parameters. Since disinfection is key in reclamation treatments, the main CCPs are linked to that process, either if only one disinfectant is applied or if a combination of two or more are used. Another key CCP is at the secondary effluent level, as raw material for the subsequent processes. APs are points where water quality and/or performance of the treatment can be easily monitored to provide additional information on the reliability of the processes.

The worldwide waste treatment industry VEOLIA ENVIRONNEMENT carried out a bibliographical review of the occupational exposure to bioaerosols in composting plants, which is based on a literature survey conducted since 1993 by the French Health and Waste Network. Composting is an aerobic biological waste treatment. Bioaerosol released from composting contains mesophilic and thermophilic microorganisms. Bacteria, fungi, particularly Aspergillus fumigatus, and thermophilic actinomycetes are the most frequent microorganisms detected in the ambient air of composting plants. These microorganisms are known to be allergenic agents. Viruses and parasites have never been investigated in the air of composting plants. Microorganism concentrations in the air vary with the seasons, the type of composting process and the waste composted. Maximum microorganism concentrations (10 3-10 5 cfu/m 3) are detected in the loading area and during waste crushing and windrows turning. Mycotoxins produced by Aspergillus fumigatus or Penicillium that are present in the ambient air of some composting plants are correlated with high concentrations of fungi spores. High concentrations of Gram negative bacteria (10 3 cfu/m 3) (Klebsiella, Proteus, Xanthomonas, Serratia…) have sometimes been detected in the ambient air of composting plants. Endotoxin concentrations in the air range from 0,3 to 5,9 ng/m 3 depending on the season. Mean dust concentrations reached 3,1 mg/m 3 but dust concentration peaks have been measured during some handlings. Dust, endotoxins and (1-3)-β-D glucan concentrations are moderately correlated in one study. Therefore it could be interesting to quantify dust concentration as an indicator of bioaerosols exposure. Considering the variability of exposure factors, additional exposure studies would be helpful to better assess the biological risk regarding specific processes and work organisation in order to optimize preventive measures towards bioaerosols occupational exposure in composting plants.