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 2024 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 4
no trend 4
downward trend 2
Greenland-Scotland ridge upward trend 0
no trend 3
downward trend 8
Norwegian Sea upward trend 1
no trend 3
downward trend 1
total upward trend 5
no trend 10
downward trend 11
2 Norwegian Trench upward trend 4
no trend 7
downward trend 5
Northern North Sea upward trend 0
no trend 8
downward trend 2
Skagerrak and Kattegat upward trend 3
no trend 16
downward trend 7
Southern North Sea upward trend 1
no trend 18
downward trend 13
Channel upward trend 0
no trend 20
downward trend 7
total upward trend 8
no trend 69
downward trend 34
3 Irish and Scottish West Coast upward trend 0
no trend 24
downward trend 13
Irish Sea upward trend 1
no trend 20
downward trend 14
Celtic Sea upward trend 0
no trend 24
downward trend 9
total upward trend 1
no trend 68
downward trend 36
4 Northern Bay of Biscay upward trend 0
no trend 24
downward trend 3
Iberian Coast upward trend 0
no trend 6
downward trend 16
Gulf of Cadiz upward trend 0
no trend 1
downward trend 0
total upward trend 0
no trend 31
downward trend 19


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 40
no trend 40
downward trend 20
Greenland-Scotland ridge upward trend 0
no trend 27
downward trend 73
Norwegian Sea upward trend 20
no trend 60
downward trend 20
total upward trend 19
no trend 39
downward trend 42
2 Norwegian Trench upward trend 25
no trend 44
downward trend 31
Northern North Sea upward trend 0
no trend 80
downward trend 20
Skagerrak and Kattegat upward trend 12
no trend 61
downward trend 27
Southern North Sea upward trend 3
no trend 56
downward trend 41
Channel upward trend 0
no trend 74
downward trend 26
total upward trend 7
no trend 62
downward trend 31
3 Irish and Scottish West Coast upward trend 0
no trend 65
downward trend 35
Irish Sea upward trend 3
no trend 57
downward trend 40
Celtic Sea upward trend 0
no trend 73
downward trend 27
total upward trend 1
no trend 65
downward trend 34
4 Northern Bay of Biscay upward trend 0
no trend 89
downward trend 11
Iberian Coast upward trend 0
no trend 27
downward trend 73
Gulf of Cadiz upward trend 0
no trend 100
downward trend 0
total upward trend 0
no trend 62
downward trend 38


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 9
red 2
Greenland-Scotland ridge green 12
red 0
Norwegian Sea green 3
red 3
total green 24
red 5
2 Norwegian Trench green 14
red 2
Northern North Sea green 15
red 0
Skagerrak and Kattegat green 21
red 5
Southern North Sea green 34
red 2
Channel green 29
red 0
total green 113
red 9
3 Irish and Scottish West Coast green 42
red 0
Irish Sea green 43
red 3
Celtic Sea green 37
red 0
total green 122
red 3
4 Northern Bay of Biscay green 32
red 0
Iberian Coast green 24
red 1
Gulf of Cadiz green 1
red 0
total green 57
red 1


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 82
red 18
Greenland-Scotland ridge green 100
red 0
Norwegian Sea green 50
red 50
total green 83
red 17
2 Norwegian Trench green 88
red 12
Northern North Sea green 100
red 0
Skagerrak and Kattegat green 81
red 19
Southern North Sea green 94
red 6
Channel green 100
red 0
total green 93
red 7
3 Irish and Scottish West Coast green 100
red 0
Irish Sea green 93
red 7
Celtic Sea green 100
red 0
total green 98
red 2
4 Northern Bay of Biscay green 100
red 0
Iberian Coast green 96
red 4
Gulf of Cadiz green 100
red 0
total green 98
red 2


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 -2.51 0.38 -1.89 0.08 0.15
Greenland-Scotland ridge -4.68 0.36 -4.08 0.01 0.02
Norwegian Sea -1.47 0.51 -0.62 0.23 0.54
Norwegian Trench -2.92 0.31 -2.40 0.05 0.09
Northern North Sea -2.28 0.33 -1.73 0.10 0.18
Skagerrak and Kattegat -2.64 0.25 -2.23 0.07 0.11
Southern North Sea -2.35 0.21 -2.00 0.10 0.14
Channel -2.75 0.23 -2.36 0.06 0.09
Irish and Scottish West Coast -5.30 0.20 -4.97 0.01 0.01
Irish Sea -2.81 0.19 -2.50 0.06 0.08
Celtic Sea -4.01 0.21 -3.67 0.02 0.03
Northern Bay of Biscay -3.00 0.22 -2.64 0.05 0.07
Iberian Coast -3.44 0.27 -3.00 0.03 0.05