In vivo bioconcentration of a metal mixture by Danio rerio eleutheroembryos

International audienceExposure to heavy metals has represented one of the most serious health risks of environmental pollution over the last 50 years. Most of the bioconcentration studies that have been carried out to date explored only individual contaminants, unlike the real situations that occur in the environment. In this work, zebrafish eleutheroembryos were exposed to a mixture of CH3Hg(II), iAs(III), Ag(I) and Cd(II), and new BCFs were calculated and compared with those calculated from single metal exposures. In both cases, experimental conditions meet the OECD Test 305 conditions established for aquatic systems. In addition, spatial imaging obtained by laser ablation coupled to inductively plasma mass spectrometry (LA-ICP/MS), has been directly performed in these samples providing complementary information. The new BCF's have revealed some differences compared to single metal exposures when eleutheroembryos were exposed to the metal mixture, especially for iAs(III) and Cd(II). LA-ICP/MS images are in good agreement with the BFC's found, representing an interesting approach to get spatial distribution of metals that reinforces the toxicokinetic information

Bioconcentration of pesticides in Zebrafish eleutheroembryos (Danio rerio)

The feasibility of a bioaccumulation test based on the use of zebrafish eleutheroembryos as an alternative to adult-individual-based approaches for REACH application has been evaluated for three test compounds, chlorpyrifos, dicofol and atrazine. Following the OECD 305 guidelines, zebrafish eleutheroembryos (72 h after hatching, hpf) were separately exposed to the investigated pesticides at two nominal concentrations below 1% of its corresponding LC50. The uptake experiments lasted for 48 h. Then, the exposure medium was replaced by a non-contaminated medium for depuration experiments (up to 72 h). Zebrafish eleutheroembryos (larvae 144 hpf, i.e. at the end of the depuration step) and their corresponding exposure media was sampled at ten different times during each experiment and the concentration of the investigated pesticide determined in both the organisms and in the exposure medium. The experimentally determined pesticide accumulation profiles in the eleutheroembryos demonstrated that atrazine has a very fast accumulation kinetic, reaching steady sate (SS) within 24 h. Chlorpyrifos and dicofol did not reach the SS within the 48-h uptake experiments although they exhibit higher accumulations than the former pesticide. Two toxicokinetic models were used to calculate the bioconcentration factor (BCF) of the studied pesticide in zebrafish eleutheroembryos. In the former, the BCF was calculated under SS conditions (BCFSS). The second was used when the compounds did not reach the SS during the uptake experiment (BCFk). Log BCF values of 3.55 and 3.84 for chlorpyrifos; 0.6 and 1.17 for atrazine, and 3.90 for dicofol were experimentally calculated at selected exposure concentrations. These values have been compared with those reported in related bioaccumulation studies and official databases.S. El-Amrani thanks to Ministry of Education and Science for the AECI predoctoral fellowship. This work was supported by Projects CTQ2008-01031/BQU from Spanish Science and Innovation Department, 046/PC08/2-14.4 from Spanish Environmental Department and project S2009/AGR-1464 (ANALISYC-II) from the Comunidad Autónoma of Madrid (Spain). Collaboration between UCM and CSIC has been carried out as Group of Environmental and Bioanalytical Chemistry.Peer reviewe

Zebrafish (<i>Danio rerio</i>) Eleutheroembryo-Based Procedure for Assessing Bioaccumulation

This paper reports on the development and preliminary evaluation of a new bioaccumulation test based on the use of zebrafish <i>(Danio renio)</i> eleutheroembryos (72 h after hatching, corresponding to 144 h post fertilization, hpf) as an alternative to adult fish-based procedures for regulatory purposes regarding REACH application. The proposed test accomplished the OECD 305 guideline and consists of a 48 h uptake period followed by a 24 h depuration step. Bioaccumulation experiments were performed for a selected of hyper hydrophobic chemicals (log <i>K</i>_ow> 7.6), that is, PCB 136 and PBDE 154 at two concentration levels corresponding roughly to 1% and 0.1% the chemicaĺs LC₅₀(nominal concentrations of 4.0 and 12.0 μg/L for PCB 136, and 1.0 and 5.0 μg/L PBDE 154, respectively). Toxicokinetic models were used to calculate the bioconcentration factors (BCFs) based on of the chemical concentrations found in the contaminated eleutheroembryos and their surrounding media. The experimentally determined accumulation profiles show bioaccumulation by zebrafish eleutheroembryos of both chemicals, and that the process is more complex than simple water–lipid partition. Calculated log BCFs using a first-order accumulation model­(3.97 and 3.73 for PCB 136, and 3.95 and 4.29 for PBDE 154) were in the range of those previously reported in the literature. The suitability of this new nonprotected life stage bioaccumulation protocol for BCF estimation was evaluated by application to widely divergent micropollutants with different accumulation mechanisms. The results were compared with those in the MITE-NITE database for adult rice fish (<i>Oryzias latipes</i>)

Development of an analytical procedure for weathered hydrocarbon contaminated soils within a UK risk-based framework.

A sequential ultrasonic extraction method for contaminated soils with weathered hydrocarbons is presented. The method covers the determination of total petroleum hydrocarbons between nC(8) and nC(40), and subranges of hydrocarbons including diesel range organic compounds, kerosene range organic compounds, and mineral oil range organic compounds in soils. Further modifications to the carbon banding may be made as requested for risk assessment. These include a series of ranges known as Texas banding (from the Texas Risk Reduction Program) as well as separation of the aliphatic and aromatic fractions. The method can be routinely used for measuring hydrocarbons down to 10 mg kg(-1) in soil. Lower limits can be achieved by employing a suitable solvent concentration step following extraction; however, this would result in increased cycle time. Detection limits may vary for individual carbon ranges calculated on the percentage of the full range they cover. With an extraction efficiency and recovery between &gt;= 95 and 99%, this method can be easily positioned as a good alternative to Soxhlet extraction and shows a good potential for implementation as a standard method potentially providing further insight to the contaminated land sector