No abstract

In response to a range of Cd concentrations, the root tips of Cdtolerant plants of Silene

The production of phytochelatins in roots of both cadmium-sensitive and cadmium-tolerant plants of Silene vulgaris (Moench) Garcke in response to Cd supply was recorded over a 7-day growth period. At the same level of Cd, sensitive plants produced more phytochelatins than tolerant ones. In sensitive roots this higher production of PCs was associated with a higher Cd content within one day. From the third day, however, Cd contents were similar, but the difference in PC production persisted. Exposure to buthionine sulphoximine strongly inhibited the production of phytochelatins in roots during cadmium treatment in both sensitive and tolerant plants, but only affected root growth of sensitive plants. Sensitive plants exhibited a higher Cd uptake, which was manifested in a higher Cd accumulation in the shoot. It is concluded that differential cadmium tolerance mechanism in Silene vulgaris is not due to differential production of phytochelatins.

The object of this study was to investigate the formation of pyrene metabolites by the isopod Porcellio scaber as a possible tool in the environmental risk assessment of polycyclic aromatic hydrocarbon (PAH) exposure in terrestrial ecosystems. The formation of pyrene metabolites was studied after either pulse exposure to a single high dose, or prolonged exposure (14 d) to a lower dosage. Exposure studies were carried out with unlabeled or radiolabeled pyrene, ion pair chromatography was used for analysis, and reference conjugates were synthesized. We also measured pyrene metabolites in field-exposed animals, to explore their use as biomarkers of PAH exposure. Analysis of the hepatopancreas and gut of single isopods revealed the formation of five products, one of which was 1-hydroxypyrene. Four of the remaining products were identified as phase II metabolites of 1- hydroxypyrene, with UV absorption and fluorescence characteristics similar to that of pyrene. One metabolite was identified as pyrene-1-glucoside, which is in accordance with high rates of glucosidation, reported for these isopods. Another conjugate was identified as pyrene-1-sulfate. None of the metabolites coeluted with a pyrene-1-glucuronide reference obtained from fish bile. A fifth metabolite detected by on-line scintillation detection did not exhibit any absorption at 340 nm, possibly because one of the aromatic rings of pyrene had lost its aromatic character. Although pyrene is not known for its toxicity, it usually co-occurs with other PAHs that are transformed into toxic products. Investigating the metabolism of pyrene can provide information with regard to the biotransformation capacity of invertebrate species and uptake and elimination kinetics. Because pyrene is one of the most predominant PAHs in the environment, analysis of its metabolites provides an extra tool for the environmental risk assessment of ecosystems with regard to PAH exposure, bioavailability, and biotransformation.

There is no uniform Persistent, Bioaccumulative, Toxic (PBT) or very Persistent, very Bioaccumulative (vPvB) assessment of chemicals in Europe, as the various regulatory frameworks use only limited or dissimilar PBT assessments, or none at all. The European REACH Regulation requires a PBT/vPvB assessment for all chemical substances that are produced within or imported into the EU in amounts exceeding 10 tonnes per year, using the criteria as described in REACH Annex XIII. However, not all substances on the EU market need to be screened according to these criteria under REACH. For a number of substances, such as those imported or produced in lower volumes, there is no REACH requirement, and for human and veterinary medicinal products, biocides, plant protection products, and food and feed additives, other EU legislation is in force to regulate their marketing and use. Compounds may also be screened for PBT properties within international agreements, such as the Oslo Paris Convention (OSPAR), the IMO Ballast Water Management Convention, the UNECE POP Protocol, and the UNEP Stockholm Convention on Persistent Organic Pollutants (POPs), which all have their own set of PBT or POP criteria. This study compares the PBT/vPvB assessment under REACH with PBT or POP assessments performed within other regulatory frameworks. Attention is paid to the process of PBT/vPvB/POP identification and which legislative steps can be taken if the PBT/vPvB/POP status is assigned. In addition to the different PBT or POP criteria of the various frameworks, descriptions of these criteria and approaches for application of weight of evidence also vary. Some EU frameworks still refer to the criteria in the former Technical Guidance Documents (TGD) of 2003, which preceded REACH. Although differences between the old TGD criteria and those in the REACH Annex XIII are small, this does cause dissimilarities among the frameworks. The risk management follow‐up of a PBT or vPvB identification, which may include a socio economic analysis, also depends on the legal framework and the specific conditions under which a substance is used. Irrespective of the framework in which a substance is used, individual European Member States may propose a substance evaluation for PBT or vPvB identification under REACH. However, authorization is only possible for uses of PBT substances that are not covered by their regular framework but are registered under REACH. How socio‐economic criteria should be weighed against PBT/vPvB properties and environmental risks in authorizing or restricting the use of PBT/vPvB substances is often not specified. Thus, although the goal of restricting or banning the use of PBT/vPvB substances is shared among all EU‐based regulatory frameworks, there are many differences in how to achieve this goal. These differences create a challenge to harmonize the PBT/vPvB assessment of substances, not only regarding technical criteria, but also regarding regulatory follow‐up. Integr Environ Assess Manag 2012; 8: 359–371. © 2011 SETAC