Regional assessment of status against human health thresholds in PCB concentrations in biota

Overview

This document provides additional regional assessments of the status of PCB concentrations in biota based on human health rather than environmental thresholds. The regional assessments are part of the 2022 OSPAR CEMP assessment and concern the PCB SCB6 which is compared against the Maximum Permissible Concentration (MPC). Methodological details are only described briefly: further information can be found here.


Summary of individual time series results

This section summarises the individual time series assessments of trend and status for SCB6. This is the only place where trends are presented as the focus of this document is on status relative to the MPC.

The first tab show the trend and status assessments for SCB6. The colours have the following meaning:

  • green: the mean concentration is significantly (p < 0.05) below the MPC
  • red: the mean concentration is not signficantly below the MPC
  • black: there are no assessment criteria available

And the shapes have the following meaning:

  • downward triangle: the mean concentration is significantly decreasing (p < 0.05)
  • circle: there is no significant change in mean concentration (p > 0.05) or there are too few years to test for trends
  • upward triangle: the mean concentration is significantly increasing (p < 0.05)

The second set of tabs give:

  • the number of time series with upwards, downwards or no trend in each MIME and OSPAR region
  • the same information presented as proportions
  • the number of time series with green or red status in each MIME and OSPAR region
  • the same information presented as proportions


SCB6


Trend summary (numbers)

Number of time series with upwards, downwards or no trend by MIME and OSPAR region

OSPAR region MIME region status SCB6
1 Barents Sea upward trend 1
no trend 5
downward trend 2
Greenland-Scotland ridge upward trend 0
no trend 2
downward trend 9
Norwegian Sea upward trend 0
no trend 3
downward trend 1
total upward trend 1
no trend 10
downward trend 12
2 Norwegian Trench upward trend 3
no trend 9
downward trend 4
Northern North Sea upward trend 0
no trend 7
downward trend 3
Skagerrak and Kattegat upward trend 0
no trend 19
downward trend 8
Southern North Sea upward trend 5
no trend 22
downward trend 6
Channel upward trend 0
no trend 20
downward trend 5
total upward trend 8
no trend 77
downward trend 26
3 Irish and Scottish West Coast upward trend 1
no trend 13
downward trend 12
Irish Sea upward trend 0
no trend 17
downward trend 16
Celtic Sea upward trend 0
no trend 19
downward trend 6
total upward trend 1
no trend 49
downward trend 34
4 Northern Bay of Biscay upward trend 0
no trend 26
downward trend 2
Iberian Sea upward trend 0
no trend 6
downward trend 20
Gulf of Cadiz upward trend 0
no trend 1
downward trend 0
total upward trend 0
no trend 33
downward trend 22


Trend summary (proportions)

Proportion of time series with upwards, downwards or no trend by MIME and OSPAR region

OSPAR region MIME region status SCB6
1 Barents Sea upward trend 13
no trend 62
downward trend 25
Greenland-Scotland ridge upward trend 0
no trend 18
downward trend 82
Norwegian Sea upward trend 0
no trend 75
downward trend 25
total upward trend 4
no trend 44
downward trend 52
2 Norwegian Trench upward trend 19
no trend 56
downward trend 25
Northern North Sea upward trend 0
no trend 70
downward trend 30
Skagerrak and Kattegat upward trend 0
no trend 70
downward trend 30
Southern North Sea upward trend 15
no trend 67
downward trend 18
Channel upward trend 0
no trend 80
downward trend 20
total upward trend 7
no trend 69
downward trend 24
3 Irish and Scottish West Coast upward trend 4
no trend 50
downward trend 46
Irish Sea upward trend 0
no trend 52
downward trend 48
Celtic Sea upward trend 0
no trend 76
downward trend 24
total upward trend 1
no trend 58
downward trend 41
4 Northern Bay of Biscay upward trend 0
no trend 93
downward trend 7
Iberian Sea upward trend 0
no trend 23
downward trend 77
Gulf of Cadiz upward trend 0
no trend 100
downward trend 0
total upward trend 0
no trend 60
downward trend 40


Status summary (numbers)

Number of time series with each status by MIME and OSPAR region

OSPAR region MIME region status SCB6
1 Barents Sea green 10
red 1
Greenland-Scotland ridge green 11
red 0
Norwegian Sea green 3
red 3
total green 24
red 4
2 Norwegian Trench green 14
red 3
Northern North Sea green 15
red 1
Skagerrak and Kattegat green 24
red 6
Southern North Sea green 34
red 2
Channel green 29
red 1
total green 116
red 13
3 Irish and Scottish West Coast green 28
red 0
Irish Sea green 37
red 3
Celtic Sea green 31
red 1
total green 96
red 4
4 Northern Bay of Biscay green 33
red 0
Iberian Sea green 25
red 1
Gulf of Cadiz green 0
red 1
total green 58
red 2


Status summary (proportions)

Proportion of time series with each status by MIME and OSPAR region

OSPAR region MIME region status SCB6
1 Barents Sea green 91
red 9
Greenland-Scotland ridge green 100
red 0
Norwegian Sea green 50
red 50
total green 86
red 14
2 Norwegian Trench green 82
red 18
Northern North Sea green 94
red 6
Skagerrak and Kattegat green 80
red 20
Southern North Sea green 94
red 6
Channel green 97
red 3
total green 90
red 10
3 Irish and Scottish West Coast green 100
red 0
Irish Sea green 92
red 8
Celtic Sea green 97
red 3
total green 96
red 4
4 Northern Bay of Biscay green 100
red 0
Iberian Sea green 96
red 4
Gulf of Cadiz green 0
red 100
total green 97
red 3


Regional assessment - methods

For a regional status assessment, the status of each time series is summarised by the difference between the estimated mean log concentration in the final monitoring year and the log MPC. The regional status for SCB6 is then estimated by fitting the following linear mixed model by restricted maximum likelihood:

  • response: status (mean log concentration - log MPC)
  • fixed model: region
  • random model: station + status estimation variation + residual variation

There are no restrictions on the time series used in the status meta-analysis based on the classification of the monitoring station; time series from baseline, representative and impacted stations are all included. However, the few time series with a non-parametric assessment of status must be excluded, because there is no summary measure of status to use in the mixed model.

The meta-analysis is restricted to regions with at least three status stations with good geographic spread.

The results of the status regional assessments are back-transformed for presentation. The estimated regional status is then interpreted as the ratio of the mean regional concentration to the assessment concentration. For example, a value of 1 indicates that the mean regional concentration is equal to the assessment concentration; a value of 0.5 indicates that it is half the assessment concentration, and a value of 2 indicates that it is twice the assessment concentration.


Regional assessment - availability of time series

This section provides more detail on the number and geographic spread of the time series available for the meta-analyses. The tabs show the stations with parametric status assessments for each OSPAR region in turn. The following regions have an insufficient number or time series or spread of stations and are excluded from the regional assessment: Gulf of Cadiz.


OSPAR region 1


OSPAR region 2


OSPAR region 3


OSPAR region 4


Regional status compared to the Maximum Permissible Concentration (MPC)

The first 2 tabs show:

  • Regional status: estimates of the regional status for SCB6 with pointwise upper one-sided 95% confidence intervals
  • Individual time series: the status estimates from the individual time series on which the regional assessment is based. The estimates for regions with insufficient geographic spread (and excluded from the meta-analysis) are also shown.

The symbols in all the plots have the following interpretation:

  • green: the mean concentration is significantly (p < 0.05) below the MPC
  • red: the mean concentration is not significantly below the MPC

The final tab shows the estimates of the regional status in SCB6.


Regional status


Individual time series


Estimates by region

This table shows the estimates of the regional status:

  • status: the estimated mean log concentration minus the log MPC
  • se: the corresponding standard error
  • upper: the corresponding pointwise upper one-sided 95% confidence limit
  • concentration: the estimated mean concentration relative to the MPC
  • conc upper: the corresponding pointwise upper one-sided 95% confidence limit


MIME region status se upper concentration conc upper
Barents Sea -2.75 0.39 -2.10 0.06 0.12
Greenland-Scotland ridge -4.53 0.39 -3.88 0.01 0.02
Norwegian Sea -1.68 0.54 -0.79 0.19 0.45
Norwegian Trench -2.83 0.32 -2.31 0.06 0.10
Northern North Sea -2.38 0.34 -1.83 0.09 0.16
Skagerrak and Kattegat -2.74 0.24 -2.34 0.06 0.10
Southern North Sea -1.98 0.23 -1.60 0.14 0.20
Channel -2.63 0.25 -2.23 0.07 0.11
Irish and Scottish West Coast -5.19 0.25 -4.78 0.01 0.01
Irish Sea -2.71 0.21 -2.36 0.07 0.09
Celtic Sea -3.95 0.24 -3.56 0.02 0.03
Northern Bay of Biscay -3.05 0.23 -2.67 0.05 0.07
Iberian Sea -3.30 0.26 -2.88 0.04 0.06