Annex IX: Risks for PolyChlorinated Biphenyls (PCBs)

Transcription

1 Annex IX: Risks for PolyChlorinated Biphenyls (PCBs) Annex IX: Risks for PolyChlorinated Biphenyls (PCBs)...1 Annex IX.1. Risk for water...3 Annex IX.2. Risk for sediment...7 Annex IX.3. Risk for biota...11 Annex IX.4. Conclusions

2 The following algorithm is applied to evaluate what would be the priority for monitoring of PCBs in the environment in the context of WFD: Priority matrix i. fraction j Very high High Medium Not applicable Low OR OR OR Definition matrix i ; fraction j / PNEC matrix i >100 PEC1 matrix i ; fraction j / PNEC matrix i >1 [ matrix i ; fraction j > DL matrix i ; fraction j)/(nb all anal. matrix i ; fraction j ) 2% OR PEC1 matrix i ; fraction j matrix i ; fraction j ] matrix i ; fraction j / PNEC matrix i >10 PEC1 matrix i ; fraction j / PNEC matrix i >1 [ matrix i ; fraction j > DL matrix i ; fraction j)/(nb all anal. matrix i ; fraction j ) 2% OR PEC1 matrix i ; fraction j matrix i ; fraction j ] matrix i ; fraction j / PNEC matrix i >1 PEC1 matrix i ; fraction j / PNEC matrix i >1 [ matrix i ; fraction j > DL matrix i ; fraction j)/(nb all anal. matrix i ; fraction j ) 2% OR PEC1 matrix i ; fraction j matrix i ; fraction j ] matrix i ; fraction j / PNEC matrix i >10 [ matrix i ; fraction j >DL matrix i ; fraction j)/(nb all anal. matrix i ; fraction j ) < 2% OR PEC1 matrix i ; fraction j < matrix i ; fraction j ] No PNEC available No PEC1 available No available Very high = FALSE High = FALSE Medium = FALSE Not applicable = FALSE - 2

3 PolyChlorinated Biphenyls (PCBs) are a category of chemical compounds formed by the addition of chlorine to biphenyl. There are 10 possible positions for chlorine substitution and therefore 209 congeners are theoretically possible. With few exceptions, PCBs were manufactured as a complex mixture of congeners, through progressive chlorination of batches of biphenyl until a certain target percentage of chlorine by weight was achieved. Commercial mixtures with higher percentages of chlorine contained higher proportions of the more heavily chlorinated congeners, but all congeners could be expected to be present at some level in all mixtures. Annex IX.1. Risk for water All congeners are toxic but the most toxic and the least abundant are the co-planar ones. However, ecotoxicity data for individual PCB congeners are scarce. It is therefore not possible to derive PNEC for each individual congener. According to a draft EQS datasheet for PCBs established by the Fraunhofer Institute, the lowest aquatic toxicity concentration found in the literature is µg/l based on a chronic study result on Oncorhynchus mykiss from Birge et al., (1978) 1. Assuming this result could cover the toxicity for every congener and assuming additive effects between all the congeners, a PNEC for the sum of total PCBs can be proposed. Applying an assessment factor of 10, the resulting PNEC is µg/l, i.e. 0.9 ng/l. Still, all 209 the PCBs congeners are generally not measured. The following 7 congeners (the so-called "7 standard PCBs") are typically the most often analysed in monitoring programmes: PCB 28: (#: ) PCB 52: (#: ) PCB 101: (#: ) PCB 118: (#: ) PCB 138: (#: ) PCB 153: (#: ) PCB 180: (#: ) In addition to these 7 congeners, monitoring data for PCB 77, PCB 105 and PCB 156 were also submitted by more than 3 Member States. A total of 10 PCB congeners were therefore selected as candidate substances for prioritisation. Some Member States have also submitted data expressed as. The sum of the 7 standard PCBs is generally believed to represent approximately 50% of the sum of in environmental samples. Therefore, if only 7 standard PCBs are monitored, the proposed PNEC for those 7 PCBs would be 0.45 ng/l. But simultaneous measurements for all these 7 congeners together were not necessarily provided by the Member States. Data are sometimes available for only a few individual congeners. In order to assess the risk due to PCBs, 3 approaches will be tested: - the first approach will be to assess the risk only from monitoring results submitted as 1 Birge, W., Black, J. and Westerman, A. (1978). Effects on Polychlorinated Biphenyl compounds and proposed PCB-replacement products on embryo-larval stages of fish and amphibians. (Author communication used) Res. Rep. No 118, Water Resourc. Res. Inst., University of Kentucky, Lexington, KY. U.S. NTISPB

4 - the second approach will propose a tentative estimation of risk due to each individual congener - the third approach will consist in summing all the monitoring results provided for PCB on each sampling record Approach 1: assessing risk only from monitoring results submitted as 7 provided monitoring data expressed as Total PCBs. PECs are calculated with these data and compared to the PNECwater for : Total PCBs - Water PEC1 (µg/l) (only measur. (µg/l) replacing <LoDet measur. by LoDet/2) correponding total PCB PEC1 >= Priority Water Total PCBs VRAI High From these calculations, a risk is identified for PCBs in water. This information is based on monitoring data from 7 and 342 quantified analysis. Approach 2: estimation of risk due to each individual congener In this approach, it was tentatively proposed to estimate the average contribution of each congener in the sum of. Unfortunately, percentages of each congener in the environment are not known. Alternatively, it is proposed to use data from Frame et al. (1996) 2 who present congener ratios in common commercial mixtures (i.e. Aroclor 1016, 1242, 1248a, 1248g, 1254a, 1254g, 1260). Merging data from these 7 mixtures and assuming equal weights for each of them, average percentages are calculated below: Congener congener ratios in A1016 (%) congener ratios in A1242 (%) congener ratios in A1248a (%) congener ratios in A1248g (%) congener ratios in A1254a (%) congener ratios in A1254g (%) congener ratios in A1260 (%) average congener ratios in tech. mixtures (%) PCB PCB PCB 77 ~ ~ PCB PCB 105 ~ PCB 118 ~ PCB 138 ~ PCB 153 ~ PCB 156 ~ PCB 180 ~0 ~ Frame GM, Cochran JW, Boewadt SS. Complete PCB distribution for 17 Aroclor mixtures determined by HRGC systems optimized for comprehensive, quantitative, congener-specific analysis. J. High Resol. Chromatogr., 19: December Cited by US-EPA. - 4

5 It should be noted that congener ratios in commercial mixtures can hardly be seen as representative of the congener ratios in the environment. Indeed, once released into the environment, PCBs have been subjected to weathering and have been partially accumulated and metabolised by living organisms, Low chlorinated PCBs tend to be degraded faster than highly chlorinated PCBs. As a consequence, substantial changes in the congener ratios occurred and continue to occur. A relative enrichment of highly chlorinated PCB in the environment can thus be observed. Therefore, extrapolating the total amount of PCBs from the above percentages for low chlorinated congeners can lead to underestimating the risk due to. On the contrary, extrapolating the total amount of PCBs from the above percentages for highly chlorinated congeners can lead to overestimating the risk due to. Using these percentages, PEC values for are estimated from PEC values for individual congeners. Risk is then calculated: Individual PCBs - Water Congener PEC1 (µg/l) (only measur. (µg/l) replacing <LoDet measur. by LoDet/2) total PCB PEC1 >= Priority Water PCB VRAI Very high PCB VRAI Very high PCB VRAI NA PCB FAUX Very high PCB FAUX Very high PCB VRAI Very high PCB VRAI Very high PCB VRAI Very high PCB VRAI Very high PCB VRAI Very high For 1 congener among 10, risk could not be detected due to insufficient data (quality or quantity of data). Moreover, priority is deemed Very High for all others PCBs, on which monitoring data are available for 4 to 11. Approach 3: summing all the monitoring results provided for PCB on each sampling For this approach, the concentrations of all PCBs congeners measured for a given sampling (i.e. all monitoring results available for any of the PCB congeners at the same sampling point and at the same sampling date. This includes congeners measured by less than 4 Member States) were summed and compared to the PNECwater for. Note that this approach tends to underestimate the risk, because only data for a few congeners were actually provided by Member States. - 5

6 For calculating the sums, the rules given by article 5, paragraph 3, of the "Proposal for a COM Directive adopting technical specifications for chemical monitoring and quality of analytical results in accordance with WFD requirements" were followed. That is, when results of the individual congeners were below the limit of quantification, they were replaced by 0 when summing the results for all congeners. The calculated risk is then: Sum PCBs - Water PEC (µg/l) for sum of all PCB congeners (only measur. PNECwater for (µg/l) Risk for sum of all PCB congeners in water Priority Water Sum PCBs High A risk for water is detected with this third approach, with a High priority label. Moreover, it should be noted that the risk ratio is probably underestimated considering the fact that the available monitoring data, and thus the PEC do not take into account all the possible PCB congeners. - 6

7 Annex IX.2. Risk for sediment Risk for sediment is assessed by comparing PNECwater with PEC in pore water. PEC in pore water is estimated from PEC in whole sediment using the equilibrium partitioning model. Koc values were estimated with the PCKOCWIN model of EPISUITE v1.66 software 3. Note that these results are only provided for indicative purpose. The equilibrium partitioning model relies on generic parameters and very simplifying hypotheses. As for water, 3 different approaches are tested for assessing risk due to PCBs in sediment. Results for different fractions (2mm, 20µm, 63 µm) are presented. Approach 1: assessing risk only from monitoring results submitted as Total PCBs - Sed 2mm PEC1 sed 2mm (only measur. sed 2mm Replacing <LoDet measur. by LoDet/2) Total PCBs Total PCBs - Sed 20µm /(nb all anal.) PEC1 >= VRAI 2mm Very high PEC1 sed 20µm (only measur. sed 20µm Replacing <LoDet measur. by LoDet/2) /(nb all anal.) PEC1 >= 20µm Total PCBs NA Total PCBs - Sed 63µm Nb of PEC1 sed 63µm (only measur. sed 63µm Replacing <LoDet measur. by LoDet/2) /(nb all anal.) PEC1 >= 63µm Total PCBs NA Data for in sediment are quite scarce. Almost no were provided for fraction sediment 20 µm and 63µm (only one country represented). However, there are 647 (on 237 ) for fraction 2mm. A risk is shown on this latter fraction of 2 mm (Risk1~ and Risk2~ ) and are attributed a Very High priority label with this first approach. 3 EPISUITE v1.66 software: - 7

8 Approach 2: estimation of risk due to each individual congener The tables below show that in all cases but 1 (fraction sediment 63µm for congener 153), risk2 ratios are above This shows that there would be a risk for sediment due to PCBs. Still, these results should be interpreted carefully since the assumed fractions of total PCB for each congener are questionable (see chapter for water), since that equilibrium partitioning approach is an oversimplifying method and given that lots of monitoring results are actually below the limit of determination. Moreover, it should be noted that number of represented are comprised between 1 and 4 only, depending on the congeners. Individual PCBs - Sed 2mm Congener PEC1 sed 2mm (only measur. sed 2mm Replacing <LoDet measur. by LoDet/2) PEC1 >= 2mm PCB VRAI Very high PCB VRAI Very high PCB E VRAI Very high PCB VRAI Very high PCB VRAI Very high PCB VRAI Very high PCB VRAI Very high PCB VRAI Very high PCB E VRAI Very high PCB VRAI Very high - 8

9 Individual PCBs - Sed 20µm Congener PEC1 sed 20µm (only measur. sed 20µm Replacing <LoDet measur. by LoDet/2) /(nb all anal.) PEC1 >= 20µm PCB VRAI Very high PCB VRAI Very high PCB VRAI Very high PCB VRAI Very high PCB VRAI Very high PCB VRAI Very high PCB VRAI Very high PCB E VRAI Very high PCB VRAI Very high PCB E VRAI Very high Individual PCBs - Sed 63µm Congener analyse s PEC1 sed 63µm (only measur. sed 63µm Replacing <LoDet measur. by LoDet/2) /(nb all anal.) PEC1 >= 63µm PCB FAUX Very high PCB FAUX Very high PCB VRAI Very high PCB FAUX Very high PCB VRAI Very high PCB FAUX Very high PCB FAUX Very high PCB NA PCB VRAI Very high PCB FAUX Very high - 9

10 Approach 3: summing all the monitoring results provided for PCB on each sampling Sum PCBs - Sed 2mm PEC1= in sed 2mm Nb Risk for sum of all PCB for sum of PNECsed for of congeners all PCB congeners 2mm in sed 2mm (only measur. Sum PCBs Medium Sum PCBs - Sed 20µm PEC1= in sed 2mm Nb Risk for sum of all PCB for sum of PNECsed for of congeners all PCB congeners 2mm in sed 2mm (only measur. Sum PCBs Medium Sum PCBs - Sed 63µm PEC1= in sed 2mm Nb Risk for sum of all PCB for sum of PNECsed for of congeners all PCB congeners 2mm in sed 2mm (only measur. Sum PCBs Medium Results from this approach tend to indicate a risk for sediment for both fractions sediment 2mm, 20µm and 63 µm. Results for the two first fractions are calculated from quite a substantial dataset (4816 and 2443 analysis) as it can be shown above. - 10

11 Annex IX.3. Risk for biota Many of the toxic responses described for PCBs have been related to the 12 congeners that adopt a coplanar configuration and which are said to be "dioxinlike". Non dioxin-like PCBs have a different toxicological profile. They show effects for reproductive toxicity, neurotoxicity, and alterations in thyroid hormone levels (van Wezel et al., 1999) 4. But simultaneous exposure to non-dioxin-like and dioxin-like congeners hampers the interpretation of the results of the toxicological and epidemiological studies. The data set on effects of individual non-dioxin-like PCBs is rather limited. The adverse effects reported in laboratory animals were effects on the thyroid, liver and brain biochemistry, as well as immunotoxicity, oestrogenicity, and reproductive and neuro-developmental effects (EFSA, 2005) 5. For repro/developmental effects, dioxin-like congeners may be an order of magnitude or so more potent than the non-dioxin-like congeners. But, overall, and given the important limitations of the data set, no much difference in potency between the dioxin-like and non-dioxin-like congeners that have been studied to date on the other endpoints can be concluded (with the exception of congener 126). For the dioxin-like congeners, congener 126 is the most potent, with effects at mg/kg bw /day. Congeners 77, 118, and 156 had effects at the lowest doses of 10-2 to 10-1 mg/kg bw /day with congener 169 at 1 10 mg/kg bw /day. For the nondioxin-like congeners 28, 128, and 153 had the lowest LOAELs/NOAEL between 10-2 and 10 mg/kg bw /day, whereas congeners 47 and 95 had unbounded LOAELs of about 10 mg/kg bw /day (Rice, 2005) 6. This would result in PNEC oral ranging from 0.02 to 2000 µg/kg food depending on the effects and congeners into consideration. The WHO (WHO. 2003) 7 and ATSDR (ATSDR. 2000) 8 propose a TDI of 0.02 µg/kg bw /day for via diet. RIVM (Baars et al,. 2001) 9 proposes a TDI of 0.01 µg/kg bw /day (. via diet). Assuming that: - these TDI may not be exhausted for more than 10% by consumption of fishery products. - the average daily consumption of fishery products is 115 g. - these TDI apply for a person weighting 70 kg. 4 van Wezel, A., Traas, T., Polder, M., Posthumus, R., van Vlaardingen, P., Crommentuijn, T. and van de Plassche, E. (1999). Maximum Permissible Concentrations for polychlorinated biphenyls. RIVM, National Institute of Public Health and the Environment EFSA. (2005). Opinion of the scientific panel on contaminants in the food chain on a request from the Commission related to the presence of non dioxin-like polychlorinated biphenyls (PCB) in feed and food (Question N EFSA-Q ). Adopted on 8 November The EFSA Journal (2005) 284, Rice, D. (2005). Non-cancer health effects of polychlorobiphenyls (PCBs) in animals. Comparaison of potencies of individual PCB congeners on non-cancer endpoints in animal studies. Prepared for the European Food Safety Authority (EFSA). Commitment #FSA WHO. (2003). Polychlorinated biphenyls: human health aspects. Concise International Chemical Assessment Document,55. World Health Organization, Geneva. 8 ATSDR. (2000). Toxicological Profiles for PCB. Agency for Toxic s and Disease Registry, U.S. Department of Health and Human Services, Public Health Services, Atlanta, GA. 9 Baars, A., Theelen, R., Janssen, P., Hesse, J., van Apeldoorn, M., Meijerink, M., Verdam, L. and Zeilmaker, M. (2001). Re-evaluation of human-toxicological maximum permissible risk levels. RIVM, Rijsinstitut voor volksgezondheid en milieu. Report

12 A quality standard for human health of around 1 µg/kg food can then be proposed 10. This value will be used for assessing risk due to (i.e. dioxin-like and non dioxin-like congeners) via biota. Note that dioxin-like congeners are also included within the dioxin/furan category (see Annex X) and therefore will be considered twice. As for water and sediment, 3 different approaches are tested for assessing risk due to PCBs in biota. Results for 2 different fractions (fish and molluscs) are presented. Approach 1: assessing risk only from monitoring results submitted as Total PCBs - Fish Nb of (>DL PEC1 in fish (µg/kg ww) (only measur. >DL) in fish (µg/kg ww) replacing <DL measur. by DL/2) Risk1 in fish for Risk2 in fish for >DL) PEC1 >= Priority Fish Total PCBs NA Total PCBs - Invertebrates Nb of (>DL PEC1 in invertebrates (µg/kg ww) (only measur. >DL) in invertebrates (µg/kg ww) replacing <DL measur. by DL/2) Risk1 in invertebrates for Risk2 in invertebrates for >DL) PEC1 >= Priority Invertebrates Total PCBs NA Data for Total PCBs in biota are very scarce as shown in the table below. No were provided for fish. Only 2 non quantified (on 2 ) are available for invertebrates. These results are below the limit of determination and do not allow to draw any conclusion µg/kgfood based on the RIVM TDI, 1.22 µg/kgfood based on the WHO & ATSDR TDI - 12

13 Approach 2: estimation of risk due to each individual congener Individual PCBs - Fish Congener Nb of PEC1 in fish (µg/kg ww) (only measur. in fish (µg/kg ww) replacing <LoDet measur. by LoDet/2) Risk1 in fish for Risk2 in fish for PEC1 >= Priority Fish PCB FAUX Very high PCB FAUX Very high PCB VRAI NA PCB VRAI Very high PCB VRAI Very high PCB FAUX Very high PCB FAUX Very high PCB FAUX Very high PCB FAUX Very high PCB FAUX Very high Individual PCBs - Invertebrates Congener Nb of PEC1 in invertebrates (µg/kg ww) (only measur. in invertebrates (µg/kg ww) replacing <LoDet measur. by LoDet/2) Risk1 in invertebrates for Risk2 in invertebrates for PEC1 >= Priority Invertebrates PCB FAUX High PCB FAUX Very high PCB FAUX High PCB FAUX Very high PCB FAUX Very high PCB FAUX Very high PCB FAUX Very high PCB FAUX Very high PCB FAUX Very high PCB FAUX Very high - 13

14 In all cases but two (PCB 77: fish and invertebrates, PCB 28: invertebrates), risk2 ratio are above 100. This tends to demonstrate a high risk for biota due to PCBs. These results should be interpreted carefully since the assumed fractions of total PCB for each congener are questionable (see chapter for water). Still, risk ratio values are so large that they tend to confirm that risk due to PCBs actually exists. Moreover, these results, even if maybe not EU representative, (number of monitoring these substances comprised between 1 and 6) are based on a substantial number of data as can be seen in the table above. Approach 3: summing all the monitoring results provided for PCB on each sampling Sum PCBs - Fish Nb of (>DL PEC in fish (µg/kg ww) for sum of all PCB congeners (only measur. >DL) ADI or PNECoral for (mg/kg food) Risk for sum of all PCB congeners in fish >DL) Priority Fish Sum PCBs Very high Sum PCBs - Invertebrates Nb of (>DL PEC in fish (µg/kg ww) for sum of all PCB congeners (only measur. >DL) ADI or PNECoral for (mg/kg food) Risk for sum of all PCB congeners in fish >DL) Priority Fish Sum PCBs Very high Results from this approach tend to indicate important risk via biota, especially via fish but also via invertebrates and the dataset allowing this conclusion is not negligible (3 to 6 represented, 101 to 1375 analysis available). Annex IX.4. Conclusions Though the assessment of risk for PCBs is somewhat uncertain and difficult, different approaches tend to indicate that PCBs pose risks of Medium to Very high priority to water, sediment and biota. - 14