Incorporation of bio-availability for the freshwater compartment Cu-example OECD Meeting, 7-8 September 2011 K Delbeke
Aim Importance of bioavailability for copper effects to freshwater organisms BLM developments Acute (US) and chronic (EU) BLM developments and validations Use of BLMs for freshwater PNECs and quality criteria 2
48h-EC50 in µg Cu/L Importance of bioavailability 400 648 300 200 0 01 02 03 05 06 07 07 08 09 11 De Schamphelaere et al, 2002 Factor 30 difference EC 50 D. magna same species, same strain, different waters Evidence on site-specific toxicity related to -DOC, ph, Hardness 3 Can we quantify the bio-availability effect?
Quantify/Predict Metal Toxicity The BIOTIC LIGAND MODEL for fish & invertebrates Ca Mg Na + H 2+ 2+ + Competition organism-water interface DOC Organic complexes Cu 2+ Toxicity Cu 2+ toxic action or transport sites = biotic ligand (BL) Toxicity Inorganic complexes (E.g. carbonates, hydroxides) WHAM (Tipping, 1994) Gill Site Interaction Model (Pagenkopf, 1983) Di Toro et al., 2001
Initial acute Fish BLM for copper Results Cu-BLM development Laboratory toxicity tests and chemistry BL - constants Log K Ca Cu-BLM P. Promelas 3.6 Derivation of stability constants Log K Mg Log K Na Log K H 3.6 3.0 5.4 Development of mathematical structure of BLM Log K Cu 7.4 - - Santore et al, 2001
BLM LC50 Predicted Cu LC50 (ug/l) Acute BLM development 00 Fathead Minnow 96h Static Exposures (Erickson et al., 1987) 0 Variations in fish LC50 : factor Predicted within factor 2 0 00 Measured Cu LC50 (ug/l) 0 Calibration to Other Organisms Applicable to other species? = calibration of Lethal accumulated concentration + LA50 - LA50 6 Santore, 2002 1 Measured LC50
BLM Predicted Cu LC50 (ug/l) Acute BLM applications to other species 0 D. magna D. pulicaria H. azteca C. dubia D. pulex Santore, 2002 1 1 0 Measured Cu LC50 (ug/l) Acute Fish BLM applicable to range of invertebrates 7
cumulative distribution Importance of bioavailability for chronic toxicity Copper Risk assessment Copper effects data-base: 139 High quality NOEC 27 species SSD 80 60 40 HC5-50 : 6-8 µg Cu/L 20 BUT huge intra-species variability!!! 0 1,0,0,0 0,0 NOEC Cu-ion concentration (µg/l) - P. promelas NOECs : between 5 and 338 µg Cu /L - R. Subcapitata NOECs : 21-306 µg Cu /L - D. magna NOECs : 16-164 µg Cu /L BLM development/validation for chronic ecotoxicity 8
EU framework chronic BLMdevelopments
predicted 72-hour EbC50 or NOEbC (µg Cu L-1) predicted ECx as Cu 2+ -activity (M) predicted 21-day NOEC or EC50 (µg Cu L-1) Chronic Cu-BLMs developed and field validated 0 B 0 observed 21-day NOEC or EC50 (µg Cu L-1) 1E-06 1E-07 1E-08 1E-09 1E-09 1E-08 1E-07 1E-06 observed ECx as Cu 2+ -activity (M) Chronic fish BLM Chronic D. magna BLM De Schamphelaere et al., 2005 De Schamphelaere et al., 2004 Relative toxicity of Cu-complexes R CuOH = K CuOHBL / K CuBL 0.2 1 R CuCO3 = K CuCO3BL 0.1 0.26 Copper constants log K CuBL 8.02 8.02 log K CuOHBL 7.32 8.02 log K CUCO3BL 7.01 7.44 Competition constants log K HBL 5.4 6.67 log K CaBL 3.47 - log K MgBL 3.58 - log K NaBL 3.19 2.91 0 Algae Bioavailability model (E b C Cu2+ ) (nm) = -114 ph 0.812 (R² = 0.91) (De Schamphelaere et al., 2003). 1 1 0 Observed 72-hour EbC50 or NOEbC (µg Cu L-1)
predicted ECx (µg Cu/L) Predicted NOEC- µg Cu/L Predicted 7-d EC60 (µg Cu/L) Chronic Cu-BLMs domains Endpoint Species Range Phys-chem Other boundaries ph H DOC DEVELOPED/VALIDATED Algae growth P. subcapitata 5.5-8.7-500 0-20 Al< 332 mg/l and Fe < 307 mg/l Invertebrate reproduction D. Magna 5.5-8.5-500 0-20 Al< 332 mg/l and Fe < 307 mg/l Fish growth O.mykiss / P.promelas 6-8.6 12-360 0-18 0 Fish Chronic fish Cu-BLM prediction for 7 days larval growth of P. promelas (data from Erickson et al, 1996) Algae E 00 P. subcapitata (NOEbC) C. reinhardtii (ErC50) C. reinhardtii (ErC) Invertebrates Measured versus predicted copper NOEC for Brachionus calcyflorus 4!hr NOEC using the chronic D. magna model for the NOEC predictions.00.00 0.00 Measured 7-d EC60 (µg Cu/L) 0 0 0 00 observed ECx (µg Cu/L) 1 1 0 Measured NOEC- µg Cu/L
cumulative distribution Predicted NOEC (µg Cu/L) BLM applications to chronic ecotoxicity data-base Copper Ecotoxicity database 00 Algae 0 Invertebrates Fish Intra-species variations from 232 to <3 1 1 0 Observed NOEC (µg Cu/L) Normalized NOECs 90 80 70 60 50 Scenario river Otter United Kingdom Scenario river Teme United Kingdom Scenario ditch The Netherlands Scenario river Rhine The Netherlands Scenario river Ebro Spain Scenario lake Monate Italy Scenario acidic lake Sweden 40 30 20 0 1 0 NOEC (µg Cu/l)
BLM applications to chronic ecotoxicity data-base Site-specific PNECs
BLM tools Acute BLMs : http://www.hydroqual.com/wr_blm.html Chronic BLMs : User-friendly tool : http://bio-met.net 14
Conclusions Copper toxicity varies clearly with water chemistry Acute BLMs were developed : US-EPA Chronic BLMs were developed for three trophic levels (algae, invertebrates and fish) - Europe. The applicability of the BLMs was demonstrated for a range of species and for a variety of natural surface water. The bio-availability normalization demonstrated significant reduction in the intra-species variability of ecotoxicity values. The incorporation of bio-availability has been crucial because it increased the reliability and ecological relevancy of the PNEC values. 15