Identification of chemical hazards for terrestrial plants in the regulatory context: Comparison of OECD and ISO guidelines

Standardized test protocols are used in the regulatory context for identifying the hazardous properties of chemicals, wastes, and contaminated materials. This paper compares the relevance of two guidelines measuring effects on terrestrial plants, the OECD TG 208 and the ISO TG 22030 and presents the scientific basis for a recent decision of the European Chemicals Agency (ECHA) under the European chemicals regulation REACH. If there are no specific phytotoxicity alerts, both guidelines are considered suitable for assessing long-term hazards, providing that a sufficient number of species is included in the OECD protocol, the recommended minimum number is six, which offer a reasonably broad selection of species to account for interspecies sensitivity. The proposed methodology, based on a combination of probabilistic assessments using Monte Carlo analysis, can be adapted for supporting similar decisions under specific regulatory processes; for example, for assessing contaminated soils or pesticides’ applications.     

Degradation of Isobutanal at High Loading Rates in a Compost Biofilter

Abstract

Biofiltration has been increasingly used for cleaning waste gases, mostly containing low concentrations of odorous compounds. To expand the application area of this technology, the biofiltration of higher pollutant loading rates has to be investigated. This article focuses on the biodegradation of isobutanal (IBAL) in a compost biofilter (BF) at mass loading rates between 211 and 4123 g/m³/day (30– 590 ppm_v). At mass loading rates up to 785 g/m³/day, near 100% removal efficiencies could be obtained. However, after increasing the loading rate to 1500–1900 g/m³/day, the degradation efficiency decreased to 62–98%. In addition, a pH decrease and production of isobutanol (IBOL) and isobutyric acid (IBAC) were observed. This is the first report showing that an aldehyde can act as electron donor as well as acceptor in a BF. To study the effects of pH, compost moisture content, and electron acceptor availability on the biofiltration of IBAL, IBOL, and IBAC, additional batch and continuous experiments were performed. A pH of 5.2 reduced the IBAL degradation rate and inhibited the IBOL degradation, although adaptation of the microorganisms to low pH was observed in the BFs. IBAC was not degraded in the batch experiments. High moisture content (51%) initially had no effect on the IBOL production, although it negatively affected the IBAL elimination increasingly during a 21–day time–course experiment. In batch experiments, the reduction of IBAL to IBOL did not decrease when the amount of available electron acceptors (oxygen or nitrate) was increased. The IBAL removal efficiency at higher loading rates was limited by a combination of nutrient limitation, pH decrease, and dehydration, and the importance of each limiting factor depended on the influent concentration.     

Vitellogenin content in European eel (Anguilla anguilla) in Flanders, Belgium

As part of a large-scale monitoring program of bioaccumulating contaminants in the European eel (Anguilla anguilla) in Flanders (Belgium), we investigated potential effects of xenoestrogens in these fish. The present paper describes the results of the plasma vitellogenin (VTG) content, measured in 142 eels sampled at 20 different locations, in relation to the internal pollution levels. To validate the blood VTG assays, a small number of eels (n=8) was exposed to 10 microg ethinylestradiol/l (EE2) for 9 days. In this experiment, VTG was detected as a protein with a molecular weight of 214 kDa and confirmed by Western blotting. Compared with the solvent controls, significantly higher concentrations of VTG were measured in EE2 exposed eel. However, the VTG content was relatively low compared with other fish species exposed to high concentrations of estrogens. The plasma VTG content of eels from the field study was very low, despite a very high internal load of endocrine disrupters. These results, together with previously published studies, suggest that immature yellow European eel might not be the best sentinel species to study the effects of estrogenic compounds on VTG levels of wild fish populations.     

Degradation of isobutanal at high loading rates in a compost biofilter

Biofiltration has been increasingly used for cleaning waste gases, mostly containing low concentrations of odorous compounds. To expand the application area of this technology, the biofiltration of higher pollutant loading rates has to be investigated. This article focuses on the biodegradation of isobutanal (IBAL) in a compost biofilter (BF) at mass loading rates between 211 and 4123 g/m3/day (30-590 ppm(v)). At mass loading rates up to 785 g/m3/day, near 100% removal efficiencies could be obtained. However, after increasing the loading rate to 1500-1900 g/m3/ day, the degradation efficiency decreased to 62-98%. In addition, a pH decrease and production of isobutanol (IBOL) and isobutyric acid (IBAC) were observed. This is the first report showing that an aldehyde can act as electron donor as well as acceptor in a BF. To study the effects of pH, compost moisture content, and electron acceptor availability on the biofiltration of IBAL, IBOL, and IBAC, additional batch and continuous experiments were performed. A pH of 5.2 reduced the IBAL degradation rate and inhibited the IBOL degradation, although adaptation of the microorganisms to low pH was observed in the BFs. IBAC was not degraded in the batch experiments. High moisture content (51%) initially had no effect on the IBOL production, although it negatively affected the IBAL elimination increasingly during a 21-day time-course experiment. In batch experiments, the reduction of IBAL to IBOL did not decrease when the amount of available electron acceptors (oxygen or nitrate) was increased. The IBAL removal efficiency at higher loading rates was limited by a combination of nutrient limitation, pH decrease, and dehydration, and the importance of each limiting factor depended on the influent concentration.