WHAT IS A ERSISTENT ORGANIC OLLUTANT (O)? Noelle Eckley Selin Joint rogram on the Science and olicy of Global Change, Massachusetts Institute of Technology Atmospheric Chemistry, Climate and Transboundary Air ollution Workshop Washington D.C., 9 June 2008
Number of Articles Os chemicals (e.g. DDT, CBs) have been regulated for decades, but the term Os emerged as part of science-policy discussions on regulations Os ARE A SCIENCE-OLICY HYBRID Earlier terms included: persistent organic contaminants, persistent organic compounds, OC, persistent semivolatile bioaccumulating organic compounds 400 350 300 250 200 150 100 50 0 Number of apers on "ersistent Organic ollutant(s)" (ISI Citation Index) Stockholm Convention signed CLRTA Os rotocol signed 2 2 6 13 [For more discussion see: N.E. Selin, From Regional to Global Information: Assessment of ersistent Organic ollutants, in R.B. Mitchell et al., eds., Global Environmental Assessments: Information and Influence, Cambridge: MIT ress, 2006.] 21 34 57 71 1993 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008* Regulatory criteria for selecting Os for regulation include: ersistence otential for long-range environmental transport Bio-accumulation Adverse effects Year 106 156 190 238 304 334 127
INTERNATIONAL CRITERIA FOR Os Bioaccumulation: Bio-accumulation factor (aquatic) > 5000 or log Kow > 5, OR Evidence of high bioaccumulation in other species, high (eco)toxicity, OR Monitoring data in biota ersistence: Half-life of 2 months in water, or 6 months in soil, or 6 months in sediment, OR Evidence of sufficient persistence to justify consideration Long-range transport potential: Measured levels in locations far from releases, OR Monitoring showing long-range environmental transport may have occurred, OR Environmental fate properties or model results showing potential for transport Air half-life > 2 days for chemicals transporting through air Adverse effects Criterion Stockholm CLRTA Bioaccumulation Log Kow 5 5 Bioaccumulation Factor 5000 5000 ersistence Water 2 months 2 months Soil 6 months 6 months Sediment 6 months 6 months Transport Air 2 days 2 days Log Kow=octanol-water partition coefficient, measure of lipophilicity Bioaccumulation factor: takes into account environmental and dietary sources [Eckley, Environment, 2001; Rodan et al., ES&T, 1999]
Log Bioaccumulation SETTING CRITERIA: WHERE ARE THE DIRTY DOZEN? 7 6 Stockholm Os Additional CLRTA Os Other chemicals Dieldrin Octachlorostyrene olychlorinated biphenyls Mirex DDT Toxaphene Chlordane Methyl mercury 5 2,3,7,8-Tetrachlorodibenzo-p-dioxin Benzo(a)pyrene (snail) 2,3,7,8-Tetrachlorodibenzofuran Hexachlorobenzene entachlorobenzene Tetrachloronaphthalene Chlordecone Hexabromobiphenyl Isodrin 4 3 Heptachlor Heptachlor epoxide Dicofol Bis-tributyl tin oxide Tetrachlorobenzene 2-Chlorophenanthrene Triphenyl Lindane(g-HCH) tin hydroxide Trifluralin Tribromobenzene endimethalin Flucythrinate Leptophos Resmethrin alpha Anthracene EN Iodofenphos -HCH Methoxychlor Ronnel Bromophos Dacthal Hexachlorobutadiene Triallate Fenvalerate Benefin Nitrofen Dibenzofuran Ethion Fluorene Triphenyl phos. TBT chloride Acenaphthylene Carbophenthion Trichlorobenzene Chlorpyrifos Hexachlorocyclopentadiene Fenthion Hexachloroethane Nonyl phenol Aldrin Benzo(a)pyrene Oxyfluorfen Chl. paraffins Endrin yrene entachloronitrobenzene entachlorophenol 2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 Soil Half-life in Months [Rodan et al., ES&T, 1999]
esticides Industrial chemicals Byproducts Os Included and roposed under Major Agreements Chemical CLRTA roposed- CLRTA Aldrin Chlordane Chlordecone DDT Dieldrin Dioxins Endosulfan Endrin Furans Heptachlor Hexabromobiphenyl Hexachlorobenzene* Hexachlorobutadiene Hexachlorocyclohexane Mirex Stockholm Octabromodiphenyl ether CB* entabromodiphenyl ether entachlorobenzene erfluorooctanesulfonate olychlorinated naphthalene olycyclic aromatic hydrocarbons Short-chain chlorinated paraffins Toxaphene [Selin and Selin, Review of European Community and International Environmental Law, 2008] roposed- Stockholm
roperties and Toxicities Availability of Data on 2465 High roduction Volume Chemicals; some illustrative properties and toxicities (IUCLID Database, 1999) Chronic toxicity to fish ersistence/stability in Soil Toxicity to Reproduction Bioaccumulation Developmental toxicity/teratogenicity ersistence/stability in Water Carcinogenicity Acute/prolonged toxicity to fish Acute oral toxicity 0 20 40 60 80 100 Data Availability (%) Source: Allanou, R., Hansen, B.G., and van der Bilt, Y. ublic Availability of Data on EU High roduction Volume Chemicals. European Commission, Joint Research Centre, European Chemicals Bureau: Ispra, Italy. [Slide: EEA]
Transport Distance in Model (km) SCREENING FOR ADDITIONAL Os Transport Distance v. Model Overall Environmental ersistence 10000000 1000000 100000 10000 1000 100 10 Hexachlorobenzene olychlorinated Biphenyls Mirex 2,3,7,8-TCDF Toxaphene 2,3,7,8-TCDD Heptachlor Epoxide DDT Chlordane Endrin Dieldrin Heptachlor Aldrin Henry's Constant > 0.001 a m-3 mol-1 Henry's Constant < 0.001 UNE O 1 1 10 100 1000 10000 100000 1000000 [Rodan et al., ES&T, 1999] Overall ersistence in Model (months) Other approaches to identify Os: Model overall environmental persistence (sometimes, different results from half-life approach, see Klasmeier et al. 2006) Screening based on quantitative structureproperty relationships (Muir and Howard, 2006 identified 30 with bioconcentration potential and 28 with transport potential) But, challenges in monitoring and measurement exist.
ADDITIONAL CONSIDERATIONS AND CHALLENGES Known, regulated Os (e.g. CBs, dirty dozen pesticides) have data available, but many of the intentionally-produced ones are no longer produced Byproduct Os (dioxins, furans) regulated in industrialized countries, continue to grow elsewhere Candidate Os (e.g. FOS, BDEs) have some data, and are emerging problems. Unidentified Os --???