ACUTE TOXICITY OF PYRITHIONE ACUTE TOXICITY OF PYRITHIONE - - PowerPoint PPT Presentation

ACUTE TOXICITY OF PYRITHIONE ACUTE TOXICITY OF PYRITHIONE PHOTODEGRADATION PRODUCTS PHOTODEGRADATION PRODUCTS TO SOME MARINE ORGANISMS TO SOME MARINE ORGANISMS

T Onduka T Onduka, K Mochida, K Ito, A Kakuno and K Fujii, , K Mochida, K Ito, A Kakuno and K Fujii, National Research Institute of Fisheries and Environment of Inla National Research Institute of Fisheries and Environment of Inland nd Sea, Fisheries Research Agency, Japan Sea, Fisheries Research Agency, Japan H Harino, Osaka City Institute of Public Health and Environmenta H Harino, Osaka City Institute of Public Health and Environmental l Sciences, Japan Sciences, Japan

International Symposium ON SHIPBUILDING TECHNOLOGY (ISST 2007)

• Fabrication and Coatings –

6-7 September 2007 Osaka University, Japan

Contents Contents

Introduction Introduction

Antifouling paint biocide Antifouling paint biocide in in Japan Japan Characteristic of Characteristic of p pyrithiones (PTs) yrithiones (PTs)

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

Antifou Antifoul ling ing paint paint biocide biocide

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 Irgarol 1051, diuron, Sea-

• Nine 211,

Nine 211, zinc pyrithione (ZnPT) zinc pyrithione (ZnPT), , copper pyrithione (CuPT) copper pyrithione (CuPT)

A Antifou ntifoul ling ing system in Japan system in Japan

Frequency of Frequency of using PTs using PTs : : 61% 61%

Diuron Pyridine- triphenylborane ZnPT CuPT Dicopper

• xide

(%)

The frequency of using antifouling biocide in Japan

Japan Paint Manufactures‘ Association (2006) 20 40 60 80

PTs are very PTs are very frequently used as frequently used as antifouling booster antifouling booster biocides biocides

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 ( Median lethal concentration (L LC50) C50), , Median effective concentration ( Median effective concentration (EC50) EC50) : : 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 Photolytic half-

• lives:

lives: 7.1 7.1– –29 minutes 29 minutes H Hydrolytic half ydrolytic half-

• lives:

lives: 12.9 12.9– –9 90< 0< day days s → → 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 the effect of the degradation products of PTs on

• n

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

N S S N N S O

3 H

N O N S S N O O N S H N S H O

Pyridine-2- sulfonic-acid (PSA) 2-mercaptopyridine- N-Oxide (POS) 2,2‘-dithio-bis- pyridine-N-Oxide ((POS)2) Pyridine-N-Oxide (PO) 2-mercaptopyridine (PS) 2,2‘-dithio-bis-pyridine (DPS）

N O C u S N O S N O Z n S N O S

ZnPT CuPT

Alga Algaｌ ｌ growth inhibition test growth inhibition test

・ 30ml f/2 medium ・ Initial cells concentration: 104cells 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 ・72-h EC50 value was estimated by probit analysis rate of growth inhibition, nominal concentration

Recommended in the test guidelines of the OECD 201

0h 24h 48h 72h

Monitor in vivo fluorescence CuPT: mostly stable ZnPT:100µg/L→7µg/L

Copepod immobilisation test Copepod immobilisation test

・ 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

Recommended in the test guidelines of the OECD 202

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 ・ 96-h LC50 value was calculated by trimmed Spearman-Karber technique fish mortality, nominal or actual concentration

0h 24h 48h 72h 96h

Change test solution, Monitor mortality

Acute toxicity of pyrithiones Acute toxicity of pyrithiones

Alga Crustacea Fish EC50 CuPT 1.5 23 9.3* ZnPT 1.6 280 98.2* EC50 LC50

* Reported by Mochida et al. (2006); the 96-h LC50 was calculated from the actual concentration

Unit : μg L-1 TBT 0.33-1.28 0.6-5.7 3.2-25.9

Previous study

・ 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 Cu2+ in seawater, and convert to CuPT f/2 medium: +1.8µg L-1 (7.1nM) of Cu2+ in seawater ZnPT the algal test range: 0.5 – 2.0µg L-1 (1.6-6.5nM) →there was enough Cu2+ to convert ZnPT to CuPT

Acute toxicity of Acute toxicity of the photodegradation products of pyrithiones the photodegradation products of pyrithiones Alga Crustacea Fish

EC50 POS 1.1 >12 500 ― (POS)2 3.4 >1 250 ― EC50 LC50 PO >100 000 >100 000 >100 000 PSA >100 000 >100 000 >100 000 DPS 65 550 520 PS 730 76 000 45 000 Unit : μg L-1

Comparison of acute toxicity of Comparison of acute toxicity of photodegradation products and pyrithiones photodegradation products and pyrithiones

Alga Crustacea Fish

EC50 POS 1.1 >12 500 ― (POS)2 3.4 >1 250 ― EC50 LC50 DPS 65 550 520 PS 730 76 000 45 000 Unit : μg L-1 CuPT 1.5 23 9.3* ZnPT 1.6 280 98.2*

Pyrithiones

Kinetics of photodegradation Kinetics of photodegradation products of pyrithiones products of pyrithiones

OH－ O O O OH- H＋ hν Redox Mn+ n Mn+

(Seymour and Bailey, 1981) (POS)2 POS ZnPT、CuPT

N S O N S O

3 H O

N S S N O O N S H O N S O

Test chemicals transfer different products Analytical methods of PTs transfer products in seawater are developing POS and (POS）2 can transform to pyrithiones

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 alga photodegradation products on algae e Future task Future task The fate of PTs in seawater The fate of PTs in seawater has to be elucidated has to be elucidated Th The e environmental PTs and photodegradation environmental PTs and photodegradation products risk assessments are needed products risk assessments are needed