ACUTE TOXICITY OF PYRITHIONE ACUTE TOXICITY OF PYRITHIONE PHOTODEGRADATION PRODUCTS PHOTODEGRADATION PRODUCTS TO SOME MARINE ORGANISMS TO SOME MARINE ORGANISMS International Symposium ON SHIPBUILDING TECHNOLOGY (ISST 2007) - Fabrication and Coatings – 6-7 September 2007 Osaka University, Japan T Onduka, K Mochida, K Ito, A Kakuno and K Fujii, , K Mochida, K Ito, A Kakuno and K Fujii, T Onduka National Research Institute of Fisheries and Environment of Inland nd National Research Institute of Fisheries and Environment of Inla Sea, Fisheries Research Agency, Japan Sea, Fisheries Research Agency, Japan H Harino, Osaka City Institute of Public Health and Environmental l H Harino, Osaka City Institute of Public Health and Environmenta Sciences, Japan Sciences, Japan
Contents Contents Introduction Introduction Antifouling paint biocide in in Japan Japan Antifouling paint biocide Characteristic of p pyrithiones (PTs) yrithiones (PTs) Characteristic of Experimental Experimental Test chemicals, organisms, and methods Test chemicals, organisms, and methods Result and Discussion Result and Discussion Acute toxicity of PTs and photodegradation products Acute toxicity of PTs and photodegradation products Comparison of toxicity of PTs Comparison of toxicity of PTs and tributyltin (TBT) in previous study and tributyltin (TBT) in previous study Conclusion Conclusion Summary and future task Summary and future task
Antifoul ling ing paint paint biocide biocide Antifou Organotin compounds (OTs) such as TBT have Organotin compounds (OTs) such as TBT have been used as antifouling biocides been used as antifouling biocides The toxicity of OTs have led to a worldwide ban The toxicity of OTs have led to a worldwide ban by the International Maritime Organization by the International Maritime Organization Candidate marine antifouling compounds Candidate marine antifouling compounds developed as alternatives to OTs developed as alternatives to OTs Irgarol 1051, diuron, Sea- -Nine 211, Nine 211, → Irgarol 1051, diuron, Sea → zinc pyrithione (ZnPT), , copper pyrithione (CuPT) copper pyrithione (CuPT) zinc pyrithione (ZnPT)
Antifou ntifoul ling ing system in Japan system in Japan A Dicopper oxide Frequency of Frequency of using PTs using PTs CuPT : 61% 61% : ZnPT Pyridine- triphenylborane PTs are very PTs are very Diuron frequently used as frequently used as antifouling booster antifouling booster 0 20 40 60 80 (%) biocides biocides The frequency of using antifouling biocide in Japan Japan Paint Manufactures‘ Association (2006)
Characteristic of Pyrithiones Characteristic of Pyrithiones PTs have toxic effects on fresh water organisms PTs have toxic effects on fresh water organisms Median lethal concentration (L LC50) C50), , Median lethal concentration ( Median effective concentration (EC50) EC50) Median effective concentration ( : 0.44 0.44– –462< 462< µ µg g L L - -1 1 : PTs degrade rapidly in the water column PTs degrade rapidly in the water column Photolytic half- -lives: lives: 7.1 7.1– –29 minutes 29 minutes Photolytic half Hydrolytic half ydrolytic half- -lives: lives: 12.9 12.9– –9 90< 0< day days s H → PTs PTs are are more stable under dark condition more stable under dark condition → The purpose of this study was to elucidate The purpose of this study was to elucidate the effect of the degradation products of PTs on on the effect of the degradation products of PTs marine organisms marine organisms
Test organisms Test organisms In the functioning of ecosystem, In the functioning of ecosystem, trophic relations are of prime importance trophic relations are of prime importance Three marine organisms, Three marine organisms, representing three trophic levels representing three trophic levels Alga: Skeletonema costatum Crustacea: Tigriopus japonicus (nauplii) Fish: Pagrus major (weight: 0.2-0.3g) )
Test Chemicals Test Chemicals O S O S N N ZnPT CuPT C Z n u N N O O S S S H O S H 3 N N N N S S O O O Pyridine-2- 2-mercaptopyridine- 2,2 ‘ -dithio-bis- sulfonic-acid N-Oxide pyridine-N-Oxide (PSA) (POS) ((POS)2) H S N N N O N S S Pyridine-N-Oxide 2-mercaptopyridine 2,2 ‘ -dithio-bis-pyridine (PO) (PS) (DPS ）
Alga ｌ ｌ growth inhibition test growth inhibition test Alga Recommended in the test guidelines of the OECD 201 ・ 30ml f/2 medium ・ Initial cells concentration: 10 4 cells mL -1 ・ Temperature 20 ℃ ・ Light source: three ultraviolet screening fluorescent tubes ・ 40-80 µmol m -2 sec -1 , 14hL:10hD ・ In vivo fluorescence of the alga directly with a fluorescence meter 0h 24h 48h 72h CuPT: mostly stable ZnPT:100µg/L → 7µg/L Monitor in vivo fluorescence ・ 72-h EC50 value was estimated by probit analysis rate of growth inhibition, nominal concentration
Copepod immobilisation test Copepod immobilisation test Recommended in the test guidelines of the OECD 202 ・ 12 wells culture plate ・ Filtered seawater ・ Five nauplii / well ・ 4 wells / concentration ・ No feed ・ Test period: 24 hours ・ Under the dark condition ・ Temperature 20 ℃ ・ Inability to swim within 15 s after gentle agitation → Immobilisation ・ 24-h EC50 value was calculated by probit analysis immobilisation rate, nominal concentration
Fish acute toxicity test Fish acute toxicity test Recommended in the test guidelines of the OECD 203 ・ 20L glass aquaria ・ 20 fishes / concentration ・ No feed, Under the dark condition ・ Temperature: 23.3-24 ℃ ・ Dissolved oxygen: 5.7-5.9 mg L -1 ・ pH: 8.1 0h 24h 48h 72h 96h Change test solution, Monitor mortality ・ 96-h LC50 value was calculated by trimmed Spearman-Karber technique fish mortality, nominal or actual concentration
Acute toxicity of pyrithiones Acute toxicity of pyrithiones Unit : μ g L -1 Alga Crustacea Fish EC50 EC50 LC50 CuPT 1.5 23 9.3* ZnPT 1.6 280 98.2* Previous study 0.33-1.28 0.6-5.7 3.2-25.9 TBT * Reported by Mochida et al. (2006); the 96-h LC50 was calculated from the actual concentration ・ Alga ： most sensitive ・ Toxicity : CuPT ＞ ZnPT to the crustacea and the fish
Discussion of acute toxicity of pyrithiones Discussion of acute toxicity of pyrithiones Toxicity Alga: CuPT = ZnPT Crustacea and fish : CuPT > ZnPT ZnPT reacts with the Cu 2+ in seawater, and convert to CuPT f/2 medium: +1.8µg L -1 (7.1nM) of Cu 2+ in seawater ZnPT the algal test range: 0.5 – 2.0µg L -1 (1.6-6.5nM) → there was enough Cu 2+ to convert ZnPT to CuPT
Acute toxicity of Acute toxicity of the photodegradation products of pyrithiones the photodegradation products of pyrithiones Unit : μ g L -1 Alga Crustacea Fish EC50 EC50 LC50 POS 1.1 >12 500 ― 3.4 >1 250 (POS)2 ― 65 550 520 DPS 730 76 000 45 000 PS >100 000 >100 000 >100 000 PO >100 000 >100 000 >100 000 PSA
Comparison of acute toxicity of Comparison of acute toxicity of photodegradation products and pyrithiones photodegradation products and pyrithiones Unit : μ g L -1 Alga Crustacea Fish EC50 EC50 LC50 POS 1.1 >12 500 ― (POS)2 3.4 >1 250 ― 65 550 520 DPS 730 76 000 45 000 PS Pyrithiones CuPT 1.5 23 9.3* ZnPT 1.6 280 98.2*
Kinetics of photodegradation Kinetics of photodegradation products of pyrithiones products of pyrithiones (POS)2 Test chemicals transfer N N S S O different products O Redox O h ν POS POS and (POS ） 2 can OH － O O S H S H 3 S N transform to pyrithiones N H ＋ N O O O OH - O M n+ Analytical methods of S PTs transfer products in M n+ N O n seawater are developing ZnPT 、 CuPT (Seymour and Bailey, 1981)
Summary and future task Summary and future task PTs have toxic effects on marine organisms PTs have toxic effects on marine organisms The toxic influence of PTs and some of their The toxic influence of PTs and some of their photodegradation products on algae e photodegradation products on alga Future task Future task The fate of PTs in seawater The fate of PTs in seawater has to be elucidated has to be elucidated The e environmental PTs and photodegradation environmental PTs and photodegradation Th products risk assessments are needed products risk assessments are needed
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