3IMPACT OF ANTIFOULING BIOCIDES ON SEA WATER, SEDIMENT AND
MARINE ORGANISMS
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Noritaka Tsunemasa
Environment Conservation Division of the Environment Bureau, City of Hiroshima
730-8586, Hiroshima, Japan Tel: +81-82-504-2188 Fax: +81-82-504-2229
E-mail: tunemasa-n@city.hiroshima.lg.jp
Introduction This research focused on the impact of antifouling biocides on sea water, sediment and marine organisms. In Japan in 1997, worldwide from September 2008, prohibition of Ot (organotin) compounds wasintroduced. This meant that the production of paints containing TBT compounds was stopped and alternatives to the available Ot antifoulants had to be developed. It has been claimed that the decomposition characteristics of thesealternative Ot antifoulants were better than those of Ot compounds. Since the introduction of the alternative antifoulants, the accumulation of these compounds has been reported in many countries. However, the toxicity of thesecompounds has still largely gone unreported. Unlike previous research which only investigated Ot compounds, this research also looked at the Ot alternative antifoulants Irgarol 1051, Diuron, Sea-Nine 211 and TPBP.
First there was the investigation of the antifouling biocide’s concentration in sea water and sediment, then the monitoring of the effects of toxicity on the fertilized oyster and sea urchin egg’s development, followed by the calculation ofthe risk factor, and finally the evaluation of the environmental risk.
Materials and Methods
ClSea-Nine 211
ClSCH3ClO
N C8H17-nClO
CH3
NHCNCH3NCH3
H3C C HN
CH3SDiuron-B

+NH CNCH2CH2

B (CH 2)18 NH 2

NPTPBPSurvey point on surface sediment samples

NIrgarol-NNP

Survey point on seawater samples

NTPBOA

Structures of Ot alternative antifouling biocide

Survey point on sediment core samples

The investigated materials were Diuron, Sea-Nine 211, TPBP, Irgarol 1051 which were all thought to be popularly used in Japan.The oysters came from the breakwater in Itsukaichi Nishi Ward, Hiroshima, Japan. Professor KenjiTorigoe, from the Department of Education at Hiroshima University, identified the oysters used in the experiments as Crassostrea gigas. The sea urchins were purchased from Taguchi Educational Laboratory. All theurchins used were Hemicentrotus pulcherrimus from Miura Peninsula in Kanagawa Pref., Japan. Seawater samples were collected from 2002 to 2004. Surface sediment samples were collected from 2002 to 2005. Sediment coresamples were collected in December 2004 and March 2005.

Results
Table 1. Minimum-maximum concentrations ofinvestigated compounds in sea water samples.
point number Irgarol 1051
M11
ND
ND-1.1
2
ND
ND- 1.3
3
ND
ND-1.1
4ND
ND-0.051
5ND
ND-0.106ND
ND-0.107ND
ND
8ND-0.092
ND9ND
ND-0.060
ND: not detected

DiuronND-0.43
ND-0.73
ND-0.21
ND-0.17
ND-0.24
ND-0.10
ND-0.14
ND-0.18
ND-0.17

Table 2. Minimum-maximum concentrations ofinvestigated compounds in surface sediment samples.

Sea-Nine 211
ND-0.1
ND-0.1
ND-0.097
ND
ND-0.067
ND-0.035
ND-0.085
ND-0.069
ND-0.059(㽀g/L)

point number Irgarol 1051
M11
ND-4.0ND-7.02
ND
1.0-4.03
ND-3.0ND-2.043.0
4.0-5.05
2.0-28
3.0-7.063.0
3.0-4.07ND
2.0-9.08
3.0-4.0
4.0
ND: not detected

DiuronND-25
ND-11
5.0-8.0
8.0-11
15-73
ND
17-20
ND
(㽀g/kg䡡wet)

Table 3. Minimum-maximum concentrations ofinvestigated compounds in sediment core samples.
point number Irgarol 1051
M11
2.4-27
ND-0.82
7.1-240.2-0.5
30.4-64
0.1-2.14
2.1-3.5
0.1-0.3
5
9.1-270
0.4-13
ND: not detected

Diuron1.4-13
3.9-102.5-11
3.0-7.7
11-220Fig. 1 Concentration of organotin alternativeantifoulants in sediment core samples..

Fig. 2 Concentration of organotin
compounds in sediment core samples.

Fig. 3 Concentration of heavy metals
in sediment core samples

Sea-Nine 211
ND
ND
ND-3.3
ND-0.8
7.6-140(㽀g/kg䡡dry)

Fig.4 Survival and protruding-mantle deformity rates on Crassostea gigas embryo after a period of 24h.
(µg/L)

Table 4. Lethal concentrations of antifouling compounds to Crassostea gigas embryos.
2hLC10LC50
2.6(2.5-2.7) 16(14-18)
TBT
TPT
2.4(2.3-2.5) 14(12-15)
Sea-Nine 211 7.4(6.8-7.7) 28(26-31)>1000>1000
Diuron>1000>1000
Irgarol 1051
LC50 = 50% lethal concentration(µg/l)
LC10 = 10% lethal concentration(µg/l)

Ratio(%)

Ratio(%)

24h
LC10LC50
0.36(0.31-0.39) 3.9(3.3-4.5)
0.52(0.48-0.54) 3.7(3.2-4.2)
0.90(0.89-0.91)
17(14-21)>1000>1000>1000>1000( ) = 95% confidence interval

2h
LC10LC50
1.1(1.0-1.1)
7.5(6.7-8.5)
TPBP
2.7(2.6-2.8)23(20-26)
TPBOA>1000>1000DPB>1000>1000
MPB>1000>1000Biphenyl>1000>1000
Phenol>1000>1000
Pyridine>1000>1000
Benzene>1000>1000
Boric acid
LC50 : 50% lethal concentration(µg/l)
LC10 : 10% lethal concentration(µg/l)

24h
LC10LC500.58(0.55-0.60) 6.3(5.4-7.4)
2.2(2.1-2.8)10(9.5-12)>1000>1000>1000>1000>1000>1000>1000>1000>1000>1000>1000>1000>1000>1000( ) : 95% confidence interval

Table 5. Lethal concentrations of antifoulingcompounds to Hemicentrotus pulcherrimus embryos.
2h48h
LC10LC50LC10LC5022(21-23)
73(67-80)
6.4(5.7-6.6)31(27-36)
TPBP30(28-32)
73(68-79)
TPBOA 130(120-130) 290(270-320)>1000>1000>1000>1000DPB>1000>1000>1000>1000
MPB
LC50 : 50% lethal concentration(µg/l)( ) : 95% confidence interval
LC10 : 10% lethal concentration(µg/l)

In this research, Sea-Nine 211, Irgarol 1051 and Diuron were detected in seawater samples at not detected (ND) to 0.10µg/L, ND to 0.092µg/L and ND to 0.73µg/L, respectively. However, TPBP was not detected in this research
period.In surface sediment samples, Sea-Nine 211, Irgarol 1051 and Diuron were detected at not detected (ND) to 40ng/g, ND to 28ng/g and ND to 73µg/g, respectively.As for the sediment core samples, Sea-Nine 211, Irgarol 1051
and Diuron were detected at not detected (ND) to 140ng/g, 0.4 to 270ng/g and 1.4 to 220µg/g, respectively.The toxicity (24h-LC50) of Sea-Nine 211, TPBP, TBT, TPT, Irgarol 1051 and Diuron on oyster embryos was 17µg/L, 6.3µg/L,3.9µg/L, 3.7µg/L, <1000µg/L and <1000µg/L, respectively. The toxicity (48h-LC50) of TPBP on sea urchin embryos was 31µg/L.The NOEC (non effective concentration) levels of Sea-Nine 211, TBT and TPT on oyster embryos were
under 0.10µg/L.

Discussion
The concentration of antifouling biocides in sediment core samples from Hiroshima Bay was much higher than the corresponding sea floor sample concentrations. In particular, the survey Point 5 sample had the highest observed
concentration of the alternative biocides. As shown in Figures 1 and 2, the concentration of Ot alternative antifoulants and Ot compounds at survey Point 5 began to increase from almost the same point. In the case of Ot alternative
antifoulants, it was thought that the rise in the concentration was caused by the increase of the consumption after the regulation of Ot compounds in 1990. On the other hand, in the case of Ot compounds at survey Point 5, the cause
was mainly due to the way the dock replaced the Ot compound paints with the Ot alternative antifoulants. When the regulation became effective in Japan, the Ot compounds were stripped from ships before the Ot alternative
antifoulants were painted on to the ships. In the case of this dock, the stripped pieces of Ot compound paint were not cleared from the dry dock, so when the ships were relaunched, the stripped paint chips on the ground were washedinto the sea water. Obviously, this would have had an impact on the Ot compound concentration levels shown in Figure 2.
In the evaluation of the environmental impact of these chemicals, a risk factor that used the predicted environmental concentration (PEC) divided by predicted no-effect concentration (PNEC) was used. When this value exceeded arisk factor of 1.0, it was decided the chemical had an influence on the environment. The PNEC on the aquatic organism was calculated from the examination result of the acute or chronic effect in the organism species divided byassessment factor. In this research, the chemicals resolved in the toxicity experiment were considered, so the assessment factor was set at 10.
In the case of Sea-Nine 211, the toxicity towards the oyster eggs was highest of the four chemicals detected in this research. The PEC in Hiroshima Bay was 0.1µg/L. The deformity rate of oyster embryos exceeded 10% in the solution
with a concentration of 0.1µg/L, so the NOEC was determined to be 0.1µg/L. PNEC which is the NOEC divided by assessment factor was 0.01µg/L and the chemical risk factor divided by their PNEC values was 10. In this case, therisk factor was much higher than a value of 1.0, and so it indicates that Sea-Nine 211 has an influence on the marine environment.
In recent times, the indication of delayed development of oysters in Hiroshima Bay has become more noticeable. If this trend continues, oyster numbers will decrease. If the oyster numbers decrease, there are a number of influencesthat would be possible. Oysters play an important role as natural filters for the environment so a decline in numbers could see an adverse affect on water quality of Hiroshima Bay. Also, various marine life (e.g. Acanthopagrus
schlegelii, Takifugu poecilonotus) in Hiroshima Bay use oysters as a food source so any change in numbers could affect not only the organisms which feed off them but also alternative food sources. It is clear that any decline in oyster
numbers would have a negative impact on the northern part of Hiroshima Bay’s ecosystem.
As mentioned previously, Sea-Nine 211, Diuron and Irgarol 1051 were detected while TPBP was not detected in the northern part of Hiroshima Bay. Essentially, the best antifouling biocides should show a high toxicity around thehull, but when they are released into the sea water they should resolve quickly so they do not affect the organisms which inhabit the sea water. Sea-Nine 211 has high toxicity and when it is released into the sea water it remains for along time so affects organisms. TPBP’s toxicity is the same as the toxicity of TBT and TPT, but resolves quickly in the sea water, so it does not affect organisms as much. If the toxicity is almost the same, the material (e.g. TPBP) withthe highest resolution speed should be used to lessen the impact on the ecosystem. For this reason, TPBP is the best antifouling biocide from the investigated antifouling biocides.

Conclusions
It was discovered that Ot alternative antifoulants accumulation characteristics in sediment were similar to Ot compounds, with both having much higher concentrations in sediment core thansurface sediment.
Sea-Nine 211 was present in the concentration that affected oyster embryo development, indicating that antifouling biocides have had a negative impact on the northern part of Hiroshima Bay’secosystem.
The antifouling biocides should show a high toxicity around the hull, but quickly resolve in the sea water.

Deformity embryo (A) Hemicentrotus pulcherrimus (B) Crassostea gigas.