CORESET II Project Version Made Available As Reference Material for State and Conservation 5-2016
Total Page：16
File Type：pdf, Size：1020Kb
Core indicator report – CORESET II project version Made available as reference material for State and Conservation 5-2016 TBT and imposex Key message No new evaluation has been made. Data is available and some tentative results are displayed. TBT concentrations in surface sediments exceed the GES-boundary in many areas of the Baltic Sea. Concentrations of the toxic substances at these levels pose ecotoxicological risks. However, tentative results of imposex in snails do not indicate explicitly bad environmental status, although results from many sites do show some level of disturbed conditions. Relevance of the core indicator TBT is a toxic substance that has previously been used in antifoulant paint on ships. TBT is a toxic substance that is known to affect the hormonal function in marine organisms, e.g. as imposex in marine snails. Policy relevance of the core indicator Primary importance Secondary importance BSAP Concentrations of hazardous substances Fish safe to eat Segment and Objective close to natural levels Healthy wildlife MSFD 8.1. Concentrations of contaminants Descriptor 9: Contaminants in fish and Descriptors and Criteria 8.2 Effects of contaminants other seafood for human consumption Other relevant legislation: WFD Chemical status/EQS, IMO convention (ban 2008) Core indicator report – CORESET II project version Made available as reference material for State and Conservation 5-2016 Indicator concept Good Environmental Status The concentration of TBT in sediments and resulting imposex in marine snails are used to evaluate whether an area reflects a good environmental status (GES). The GES-boundary for the concentration of TBT is an Environmental Quality Standard (EQS) developed by Sweden based on toxicity affecting sediment dwelling organisms (Table 1). EQS are derived at EU level as a substance included on the priority list under the Water Framework Directive (2000/60/EC, amended by directive (2013/39/EU) and when suitable values are not available they can be derived by Member States (WFD CIS 27). The GES-boundary for imposex in snails is based on an EcoQO developed by OSPAR (Table 1). The GES-boundary is applicable if the concentrations are measured in the appropriate matrix. For historical reasons, the Contracting Parties around the Baltic Sea have differing monitoring strategies. As a pragmatic approach, a GES-boundary is defined in this indicator however if suitable monitroing data is not available in a region the secondary GES-boundary can be used for the evaluation (Table 1). Table 1.GES-boundary for TBT concentration and imposex in snails GES-boundary Secondary GES-boundary ref. matrix concentration Tributyltin EQS sediment 1.6 µg /kg dw (5% TOC) EAC water: 0.2 ng/l, (TBT) developed by Sweden based on mussel 12 µg/kg dw toxicity (EU WFD EQS 0.02 µg/kg dw) imposex OSPAR class 2 EcoQO (see Table 2) TBT is known to accumulate in marine sediments and to affect marine organisms at very low concentrations. Therefore evaluating the environmental status based on sediment concentrations is considered more appropriate than sampling of biota or water as the concentrations in these matrixes often are very low and may be below the analytical detection limit. A scheme for assessing imposex/intersex and chemical measurements have been described by OSPAR and Strand et al (2006), and can be used to give an overall assessment of the status of TBT contamination. Biological effects assessment classes for ECOQO on imposex/intersex (Table 2). Table 2. Imposex assessment classes related to GES for gastropod snail species. (VDSI - Vas Deferens Sequence Index, ISI - intersex stage index) Assessment Species class Nucella lapillus Neptunea antiqua Hinia reticulata Buccinum undatum Hydrobia ulvae Littorina littorea Parameter VDSI VDSI VDSI VDSI VDSI ISI 1 <0.3 <0.3 2 GES 0.3 – <2 0.3 – <2 <0.3 <0.3 <0.3 3 - 2 – 4 2 – 4 0.3 – <2 0.3 – <2 0.3 – <1 <0.3 GES 4 sub >4 2 – 4 2 – 4 1 – 3 0.3 – 1.2 Core indicator report – CORESET II project version Made available as reference material for State and Conservation 5-2016 5 >1.2 If the indicator is used to evaluate the protection goal of human health, then the following boundary level can be used for TBT concentration in seafood 15.2 µg/kg ww EU foodstuff Directive (EU/1881/2006). Anthropogenic pressures linked to the indicator Strong connection Secondary connection General TBT introduced from antifoulant paint on ships MSFD Contamination by hazardous substances Annex III, - introduction of synthetic compounds Table 2 Concentration maps of TBT show spatial gradients in relation to frequency of ship densities. Ship traffic is still regarded as the main source of TBT in the marine environment, even though the amounts have decreased after the ban of use of TBT in antifoulant paint. Due to the association with shipping and boating, TBT compounds are widely spread in the Baltic Sea area. There are indications that TBT may be degrading in the environment after the ban of its use as anti-fouling paint. However, high concentration of TBT and Triphenyltin (TPhT) are found in many places and the environmental impacts are still severe. Concentrations are still high in harbours and marinas. Assessment protocol To be further developed. Conversion from wet weight –based concentrations to dry weight were made if dry weight % was provided. Sum or organotins could be considered in species with higher metabolic capacity, e.g. gfish. At least sum of TPhT+TBT should be considered for fish Relevance of the indicator Policy Relevance TBT is a substance which is identified on the priority list of the HELCOM Baltic Sea Action Plan. Tributyltin compounds (TBT-ion) are classified as Priority Hazardous substances under the daughter Directive (2008/105/EC) of the EC Water Framework Directive (2000/60/EC). The EU Marine Strategy Framework Directive (2008/56/EC) refers to the priority substances of the WFD. Progress towards good environmental status will depend on whether pollution is progressively being phased out, i.e. the presence of contaminants in the marine environment and their biological effects are Core indicator report – CORESET II project version Made available as reference material for State and Conservation 5-2016 kept within acceptable limits, so as to ensure that there are no significant impacts on, or risk to, the marine environment. In accordance with point 20 of Annex XVII to Regulation (EC) No 1907/2006 of the European Parliament and of the Council of 18 December 2006 concerning the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH), establishing a European Chemicals Agency, amending Directive 1999/45/EC and repealing Council Regulation (EEC) No 793/93 and Commission Regulation (EC) No 1488/94 as well as Council Directive 76/769/EEC and Commission Directives 91/155/EEC, 93/67/EEC, 93/105/EC and 2000/21/EC pursuant to Commission Regulation (EC) No 552/2009 of 22 June 2009 amending Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) as regards Annex XVII. Organostannic compounds shall not be placed on the market, or used, as substances or in mixtures: 1. where the substance or mixture is acting as biocide in free association paint. 2. where the substance or mixture acts as biocide to prevent the fouling by micro-organisms, plants or animals of: (a) all craft irrespective of their length intended for use in marine, coastal, estuarine and inland waterways and lakes; (b) cages, floats, nets and any other appliances or equipment used for fish or shellfish farming; (c) any totally or partly submerged appliance or equipment. 3. where the substance or mixture is intended for use in the treatment of industrial waters. On the global level, the use of TBT in antifouling paints has been banned by the 2001 International Convention on the Control of Harmful Anti-fouling Systems on Ships (AFS convention), which entered fully into force in 2008. From 1 January 2008, ships bearing an active TBT coating on their hulls will no longer be allowed in Community ports (782/2003/EC). All Baltic Sea countries except the Russian Federation have ratified the Convention. The effects of TBT in the ecosystem Tributyltin compounds (TBT-ion CAS No. 688-73-3 (36643-28-4)) belong to organotin compound (OTC) class. TBT compounds are very toxic to aquatic organisms, especially to benthic organisms. Consequences of toxic effects include shell deformation, endocrine disruption and impaired larval recruitment as well as immuno- suppression. High levels of TBT are a potential risk to human health as it may cause endocrine disruption. Several OTCs have negative toxic effects: immunosuppresion, neurotoxicity, hepatoxicity, renal and dermal toxicity, teratogenic and carcinogenic effects. Usually triorgano-compounds used as biocide – antifoulant paints, agricultural pesticides, molluscicides and wood preservative. TBT compounds are hydrophobic and associate strongly to particles in natural waters and ultimately are deposited in the sediments. Adsorption to particles of organic origin (soils and sediments) is stronger than to particles of mineral origin (soils and sediments). Degradation (photodegradation or biodegradation) of TBTs in the environment occurs due to dealkylation and depends on aerobic condition. Degradation of TBT under anaerobic condition may require a long time. The half-life of TBTs in natural waters may range from a few days to several weeks, but in soils and sediments the half- life is one to a few years. Core indicator report – CORESET II project version Made available as reference material for State and Conservation 5-2016 TBTs accumulate in organisms, the accumulation is often stronger in benthic organisms compared to fish. TBT and triphenyltin accumulate in the food web, but a large variance in accumulation potential has been found between species, even within the same trophic level.