Regional assessment of status and trends in PBDE concentrations in biota

  • Overview
  • Summary of individual time series results
  • Regional assessment - methods
  • Regional assessment - availability of time series
  • Regional trends
  • Regional status compared to the Federal Environmental Quality Guideline (FEQG)
  • Regional status compared to the Background Assessment Concentration (BAC)
  • PBDE profiles

Overview

The 2020 assessment of CSEMP data describes the status and trends of contaminant concentrations in biota and sediment at monitoring stations around the UK. Assessments are made for a large number of time series, each of a single contaminant in a single species and tissue (for biota) at a single monitoring station. This document is one of a series that synthesises the results of the individual time series to assess status and trends at the biogeographic regional level. In particular, it considers PBDE concentrations in biota, where the PBDEs are BDE28, BDE47, BDE66, BDE85, BDE99, BD100, BD153, BD154, BD183.

The regional assessment only considers coastal and offshore stations and excludes estuarine stations. The results are therefore based on the monitoring data collected within the waters assessed under the UK Marine Strategy (MS). For simplicity, the term ‘region’ is used throughout to describe biogeographic regions. MS sub-regions are always referred to as such.

The regional status assessments presented in this document are based on environmental thresholds. Regional status assessments based on human health thresholds can be found in the resource biota_regional_assessment_pbdes_health.html.

The following sections:

  • summarise the individual time series results
  • describe the methods used to combine the individual time series results to estimate regional status and trends
  • present the estimates of regional trends
  • present the estimates of regional status


Summary of individual time series results

A time series of PBDE concentrations is assessed for status if:

  • there is at least one year with data in the period 2014 to 2019
  • there are at least three years of data over the whole time series
  • a parametric model can be fitted to the data and used to estimate the mean concentration in the final monitoring year (or, occasionally, if a non-parametric test of status is applied)

The conditions are more stringent for trends. Specifically, a time series is assessed for trends if:

  • there is at least one year with data in the period 2014 to 2019
  • there are at least five years of data over the whole time series
  • a parametric model can be fitted to the data and used to estimate the trend in mean concentration

Note that all trend assessments for individual time series and most status assessments are based on the fit of a parametric model. This is important because only the parametric results are passed into the regional assessments in the following sections. 101 of the 321 PBDE time series were assessed for status using a non-parametric test.

The first tab below shows all the monitoring stations where there are individual time series assessments of trend or status for PBDEs. The purple circles are stations where there is a trend assessment for at least one PBDE, and the light blue cirles are stations where there are only status assessments. The areas delineated by the thinner black lines are the biogeographic regions; those delineated by the thicker black lines are the MS sub-regions.

The next set of tabs show the trend and status assessments for each PBDE in turn. The colours have the following meaning:

  • blue: the mean concentration is significantly (p < 0.05) below the Background Assessment Concentration (BAC)
  • green: the mean concentration is significantly (p < 0.05) below the Federal Environmental Quality Guideline (FEQG)
  • orange: there is no FEQG and the mean concentration is not significantly below the BAC
  • red: the mean concentration is not signficantly below the FEQG

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 final set of tabs give:

  • the number of time series with upwards, downwards or no trend in each biogeographic region and MS sub-region
  • the same information presented as proportions
  • the number of time series with blue, green, orange or red status in each biogeographic region and MS sub-region
  • the same information presented as proportions

Note that there are no FEQGs for BDE66, BDE85, BD126, BD183, BD209.


  • Stations
  • BDE28
  • BDE47
  • BDE66
  • BDE85
  • BDE99
  • BD100
  • BD153
  • BD154
  • BD183
  • Trend summary (numbers)
  • Trend summary (proportions)
  • Status summary (numbers)
  • Status summary (proportions)











Number of time series with upwards, downwards or no trend by biogeographic region and MS sub-region

MS sub-region biogeographic region status BDE28 BDE47 BDE66 BDE99 BD100 BD153 BD154 total
Greater North Sea Northern North Sea upward trend 0 0 0 0 0 0 0 0
no trend 1 7 1 1 3 0 0 13
downward trend 1 2 2 2 2 3 2 14
Southern North Sea upward trend 0 0 0 0 0 0 0 0
no trend 2 2 3 3 2 3 5 20
downward trend 4 6 3 1 6 0 2 22
E Channel upward trend 0 0 0 0 0 0 0 0
no trend 0 0 0 0 1 0 1 2
downward trend 1 3 0 2 1 2 1 10
total upward trend 0 0 0 0 0 0 0 0
no trend 3 9 4 4 6 3 6 35
downward trend 6 11 5 5 9 5 5 46
Celtic Seas Minches & W Scotland upward trend 0 0 0 0 0 0 0 0
no trend 0 0 0 0 0 0 0 0
downward trend 0 1 0 0 0 0 0 1
Irish Sea upward trend 0 0 0 0 0 0 0 0
no trend 0 3 2 3 2 0 6 16
downward trend 2 10 4 7 10 11 7 51
W Channel & Celtic Sea upward trend 0 0 0 0 0 0 0 0
no trend 0 0 1 1 0 0 3 5
downward trend 0 3 0 0 3 0 0 6
total upward trend 0 0 0 0 0 0 0 0
no trend 0 3 3 4 2 0 9 21
downward trend 2 14 4 7 13 11 7 58


Proportion of time series with upwards, downwards or no trend by biogeographic region and MS sub-region

MS sub-region biogeographic region status BDE28 BDE47 BDE66 BDE99 BD100 BD153 BD154 total
Greater North Sea Northern North Sea upward trend 0 0 0 0 0 0 0 0
no trend 50 78 33 33 60 0 0 48
downward trend 50 22 67 67 40 100 100 52
Southern North Sea upward trend 0 0 0 0 0 0 0 0
no trend 33 25 50 75 25 100 71 48
downward trend 67 75 50 25 75 0 29 52
E Channel upward trend 0 0 0 0 0 0 0
no trend 0 0 0 50 0 50 17
downward trend 100 100 100 50 100 50 83
total upward trend 0 0 0 0 0 0 0 0
no trend 33 45 44 44 40 38 55 43
downward trend 67 55 56 56 60 62 45 57
Celtic Seas Minches & W Scotland upward trend 0 0
no trend 0 0
downward trend 100 100
Irish Sea upward trend 0 0 0 0 0 0 0 0
no trend 0 23 33 30 17 0 46 24
downward trend 100 77 67 70 83 100 54 76
W Channel & Celtic Sea upward trend 0 0 0 0 0 0
no trend 0 100 100 0 100 45
downward trend 100 0 0 100 0 55
total upward trend 0 0 0 0 0 0 0 0
no trend 0 18 43 36 13 0 56 27
downward trend 100 82 57 64 87 100 44 73


Number of time series with each status by biogeographic region and MS sub-region

MS sub-region biogeographic region status BDE28 BDE47 BDE66 BDE85 BDE99 BD100 BD153 BD154 BD183 total
Greater North Sea Northern North Sea blue 0 0 0 0 0 0 0 0 0 0
green 12 14 0 0 12 12 12 10 0 72
orange 0 0 11 1 0 0 0 0 1 13
red 0 0 0 0 0 1 0 1 0 2
Southern North Sea blue 0 0 0 0 0 0 0 0 0 0
green 9 9 0 0 9 8 9 9 0 53
orange 0 0 9 0 0 0 0 0 0 9
red 0 0 0 0 0 1 0 0 0 1
E Channel blue 0 0 0 0 0 0 0 0 0 0
green 2 3 0 0 2 3 2 2 0 14
orange 0 0 2 0 0 0 0 0 0 2
red 0 0 0 0 1 0 0 0 0 1
total blue 0 0 0 0 0 0 0 0 0 0
green 23 26 0 0 23 23 23 21 0 139
orange 0 0 22 1 0 0 0 0 1 24
red 0 0 0 0 1 2 0 1 0 4
Celtic Seas Minches & W Scotland blue 0 0 0 0 0 0 0 0 0 0
green 2 3 0 0 2 2 2 3 0 14
orange 0 0 2 1 0 0 0 0 1 4
red 0 0 0 0 0 0 0 0 0 0
Irish Sea blue 0 0 0 0 0 0 0 0 0 0
green 15 17 0 0 14 15 16 16 0 93
orange 0 0 16 1 0 0 0 0 1 18
red 0 0 0 0 1 2 0 1 0 4
W Channel & Celtic Sea blue 0 0 0 0 0 0 0 0 0 0
green 3 3 0 0 3 3 3 3 0 18
orange 0 0 3 0 0 0 0 0 0 3
red 0 0 0 0 0 0 0 0 0 0
total blue 0 0 0 0 0 0 0 0 0 0
green 20 23 0 0 19 20 21 22 0 125
orange 0 0 21 2 0 0 0 0 2 25
red 0 0 0 0 1 2 0 1 0 4


Proportion of time series with each status by biogeographic region and MS sub-region

MS sub-region biogeographic region status BDE28 BDE47 BDE66 BDE85 BDE99 BD100 BD153 BD154 BD183 total
Greater North Sea Northern North Sea blue 0 0 0 0 0 0 0 0 0 0
green 100 100 0 0 100 92 100 91 0 83
orange 0 0 100 100 0 0 0 0 100 15
red 0 0 0 0 0 8 0 9 0 2
Southern North Sea blue 0 0 0 0 0 0 0 0
green 100 100 0 100 89 100 100 84
orange 0 0 100 0 0 0 0 14
red 0 0 0 0 11 0 0 2
E Channel blue 0 0 0 0 0 0 0 0
green 100 100 0 67 100 100 100 82
orange 0 0 100 0 0 0 0 12
red 0 0 0 33 0 0 0 6
total blue 0 0 0 0 0 0 0 0 0 0
green 100 100 0 0 96 92 100 95 0 83
orange 0 0 100 100 0 0 0 0 100 14
red 0 0 0 0 4 8 0 5 0 3
Celtic Seas Minches & W Scotland blue 0 0 0 0 0 0 0 0 0 0
green 100 100 0 0 100 100 100 100 0 78
orange 0 0 100 100 0 0 0 0 100 22
red 0 0 0 0 0 0 0 0 0 0
Irish Sea blue 0 0 0 0 0 0 0 0 0 0
green 100 100 0 0 93 88 100 94 0 81
orange 0 0 100 100 0 0 0 0 100 16
red 0 0 0 0 7 12 0 6 0 3
W Channel & Celtic Sea blue 0 0 0 0 0 0 0 0
green 100 100 0 100 100 100 100 86
orange 0 0 100 0 0 0 0 14
red 0 0 0 0 0 0 0 0
total blue 0 0 0 0 0 0 0 0 0 0
green 100 100 0 0 95 91 100 96 0 81
orange 0 0 100 100 0 0 0 0 100 16
red 0 0 0 0 5 9 0 4 0 3


Regional assessment - methods

Tabulating the number of time series with each status category by region provides a quick summary of the individual time series results. However, it does not provide an objective regional assessment of status. Similarly, tabulating the number of time series with an upward or downward trend does not provide an objective regional assessment of trend. This section describes how the individual time series results can by synthesised in a meta-analysis to assess both status and trend at the regional level.

Trends

For a regional trend assessment, the trend in each time series is summarised by the estimated change in log concentration over the last twenty years (or shorter if the time series doesn’t extend that far back). Regional trends are then estimated by fitting the following linear mixed model by restricted maximum likelihood:

  • response: trend (yearly change in log concentration)
  • fixed model: region
  • random model: PBDE + region.PBDE + station + station.PBDE + trend estimation variation + residual variation

The fixed model means that a trend is estimated for each region. Trends in the different PBDEs are assumed to be broadly similar, because inputs and control measures are likely to affect all PBDEs in a similar way. Each regional trend can thus be interpreted as the common trend in PBDE concentrations in that region (i.e. the trend averaged across all PBDEs).

The random model has six terms:

  • PBDE allows for variation in trend between PBDEs common to all regions
  • region.PBDE allows for additional variation in trend between PBDEs within regions
  • station allows for variation in trend between stations common to all PBDEs
  • station.PBDE allows for additional variation in trend between stations and PBDEs common to all tissues and species within stations
  • trend estimation variation is the variance of the trend estimates from the individual time series analysis, assumed known and fixed
  • residual variation is the variation that cannot be explained by any of the fixed effects or the other random effects

The meta-analysis is restricted to time series from monitoring stations that are classified as ‘representative’ or ‘baseline’ (near pristine conditions or only subject to very diffuse inputs). ‘Impacted’ stations (those close to a point source) are omitted because trends there will likely reflect changes due to the point source and will be ‘unrepresentative’ at the regional level.

The meta-analysis is further restricted to:

  • regions with at least three trend stations with good geographic spread. Three stations is considered the minimum required to provide some sort of evidence base at the regional level
  • PBDEs with trend information for at least three stations (over all regions): PBDEs are treated as random effects in the meta-anlaysis, so information about trends in one PBDE can be ‘borrowed’ from the trend information in the other PBDEs

Status

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 assessment concentration. This ensures that status is always measured on the same scale, even though the assessment concentration might vary between PBDEs and species. Essentially the same linear mixed model as for trends is then fitted:

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

where status estimation variation is the variation in the status estimates from the individual time series analysis, assumed known and fixed.

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.

Again, the meta-analysis is restricted to regions with at least three status stations with good geographic spread and to PBDEs with status information for at least three stations (over all regions).

Presentation

The results of both the trend and status regional assessments are back-transformed for presentation. The estimated regional trend is then interpreted as the percentage yearly change in concentration and the estimated regional status as the ratio of the mean regional concentration to the assessment concentration. To illustrate the latter, 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 map shows the stations with parametric trend and status assessments having excluded trend assessments at baseline and impacted stations. The purple circles are stations where there is a trend assessment for at least one PBDE, and the light blue cirles are stations where there are only status assessments.

The following regions have an insufficient number or time series or spread of stations and are excluded from the regional assessment:

  • trend: Minches & W Scotland
  • status: Minches & W Scotland



Regional trends

The first 4 tabs show:

  • Regional trends: estimates of the regional trend (averaged over PBDEs) with pointwise 95% confidence intervals
  • Regional trends by PBDE: regional trend estimates for each PBDE with pointwise 95% confidence intervals plotted by PBDE
  • Regional trends by region: regional trend estimates for each PBDE with pointwise 95% confidence intervals plotted by region
  • Individual time series: the trend 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 these plots have the following interpretation:

  • downward triangle: the mean concentration is significantly decreasing (p < 0.05)
  • circle: there is no significant change in mean concentration (p > 0.05)
  • upward triangle: the mean concentration is significantly increasing (p < 0.05)

The final 2 tabs show the estimates of the regional trend (averaged over PBDEs) and the regional trend by PBDE


  • Regional trends
  • Regional trends by PBDE
  • Regional trends by region
  • Individual time series
  • Estimates by region
  • Estimates by region and PBDE





This table shows the estimates of the regional trend:

  • trend: the estimated mean yearly change in log concentration across the region (multiplied by 100 for presentation)
  • se: the corresponding standard error
  • lower, upper: the corresponding pointwise 95% confidence limits
  • % yearly change: the estimated mean % yearly change in concentration across the region
  • %yc lower, %yc upper: the corresponding pointwise 95% confidence limits


biogeographic region trend se lower upper % yearly change %yc lower %yc upper
Northern North Sea -7.38 1.84 -10.98 -3.78 -7.11 -10.40 -3.70
Southern North Sea -9.58 1.59 -12.70 -6.47 -9.14 -11.93 -6.26
E Channel -11.15 2.29 -15.65 -6.65 -10.55 -14.48 -6.44
Irish Sea -13.39 1.51 -16.34 -10.44 -12.53 -15.08 -9.91
W Channel & Celtic Sea -9.29 2.25 -13.70 -4.89 -8.87 -12.80 -4.77


This table shows the estimates of the regional trend by determinand:

  • trend: the estimated mean yearly change in log concentration across the region (multiplied by 100 for presentation)
  • se: the corresponding standard error
  • lower, upper: the corresponding pointwise 95% confidence limits
  • % yearly change: the estimated mean % yearly change in concentration across the region
  • %yc lower, %yc upper: the corresponding pointwise 95% confidence limits


biogeographic region PBDE trend se lower upper % yearly change %yc lower %yc upper
Northern North Sea BDE28 -4.57 2.00 -8.49 -0.66 -4.47 -8.14 -0.66
BDE47 -8.09 1.66 -11.35 -4.83 -7.77 -10.73 -4.72
BDE66 -7.38 1.95 -11.20 -3.56 -7.11 -10.60 -3.49
BDE99 -10.55 2.01 -14.49 -6.61 -10.01 -13.49 -6.40
BD100 -7.21 1.83 -10.81 -3.62 -6.96 -10.24 -3.55
BD153 -8.77 1.95 -12.59 -4.96 -8.40 -11.83 -4.84
BD154 -5.06 1.94 -8.87 -1.26 -4.94 -8.49 -1.25
Southern North Sea BDE28 -7.80 1.60 -10.94 -4.66 -7.51 -10.37 -4.56
BDE47 -11.24 1.43 -14.04 -8.44 -10.63 -13.10 -8.09
BDE66 -8.95 1.56 -12.02 -5.89 -8.56 -11.32 -5.72
BDE99 -12.50 1.89 -16.20 -8.80 -11.75 -14.96 -8.42
BD100 -9.95 1.52 -12.93 -6.98 -9.47 -12.13 -6.74
BD153 -10.55 1.88 -14.24 -6.85 -10.01 -13.27 -6.62
BD154 -6.09 1.53 -9.10 -3.09 -5.91 -8.69 -3.04
E Channel BDE28 -8.89 2.44 -13.67 -4.10 -8.50 -12.78 -4.01
BDE47 -12.43 2.13 -16.61 -8.25 -11.69 -15.30 -7.92
BDE99 -14.26 2.46 -19.08 -9.43 -13.29 -17.37 -9.00
BD100 -11.48 2.34 -16.07 -6.90 -10.85 -14.85 -6.66
BD153 -12.14 2.46 -16.96 -7.32 -11.43 -15.60 -7.06
BD154 -7.94 2.33 -12.50 -3.38 -7.63 -11.75 -3.32
Irish Sea BDE28 -10.35 1.64 -13.57 -7.12 -9.83 -12.69 -6.88
BDE47 -14.96 1.33 -17.57 -12.35 -13.90 -16.12 -11.62
BDE66 -13.29 1.60 -16.43 -10.15 -12.45 -15.15 -9.66
BDE99 -16.19 1.63 -19.39 -12.99 -14.95 -17.62 -12.18
BD100 -14.47 1.34 -17.10 -11.85 -13.47 -15.72 -11.17
BD153 -14.31 1.51 -17.28 -11.34 -13.33 -15.87 -10.72
BD154 -10.16 1.40 -12.90 -7.42 -9.66 -12.10 -7.15
W Channel & Celtic Sea BDE47 -11.37 2.09 -15.48 -7.27 -10.75 -14.34 -7.01
BDE66 -9.02 2.41 -13.76 -4.29 -8.63 -12.85 -4.20
BDE99 -12.02 2.50 -16.92 -7.12 -11.32 -15.56 -6.87
BD100 -9.59 2.14 -13.79 -5.40 -9.15 -12.88 -5.25
BD154 -5.79 2.24 -10.17 -1.41 -5.63 -9.67 -1.40


Regional status compared to the Federal Environmental Quality Guideline (FEQG)

The first 4 tabs show:

  • Regional status: estimates of the regional status (averaged over PBDEs) with pointwise upper one-sided 95% confidence intervals
  • Regional status by PBDE: regional status estimates for each PBDE with pointwise upper one-sided 95% confidence intervals plotted by PBDE
  • Regional status by region: regional status estimates for each PBDE with pointwise upper one-sided 95% confidence intervals plotted by region
  • 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:

  • blue: the mean concentration is significantly (p < 0.05) below the Background Assessment Concentration (BAC)
  • green: the mean concentration is significantly (p < 0.05) below the FEQG
  • red: the mean concentration is not significantly below the FEQG

Note that to see why some points might be coloured blue, it is necessary to look ahead to the next section, where status is compared to the BAC. Unfortunately, it isn’t easy to present the assessment of status relative to the FEQG with the assessment of status relative to the BAC because the ratio of the BAC to the FEQG can vary between PBDEs and species.

The final 2 tabs show the estimates of the regional status (averaged over PBDEs) and the regional status trend by PBDE


  • Regional status
  • Regional status by PBDE
  • Regional status by region
  • Individual time series
  • Estimates by region
  • Estimates by region and PBDE





This table shows the estimates of the regional status:

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


biogeographic region status se upper concentration conc upper
Northern North Sea -5.19 0.94 -3.64 0.01 0.03
Southern North Sea -4.80 0.94 -3.26 0.01 0.04
E Channel -5.46 0.98 -3.85 0.00 0.02
Irish Sea -4.66 0.93 -3.12 0.01 0.04
W Channel & Celtic Sea -5.88 0.98 -4.26 0.00 0.01


This table shows the estimates of the regional trend by determinand:

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


biogeographic region PBDE status se upper concentration conc upper
Northern North Sea BDE28 -9.08 0.28 -8.62 0.00 0.00
BDE47 -4.98 0.21 -4.63 0.01 0.01
BDE66
BDE99 -4.65 0.29 -4.18 0.01 0.02
BD100 -2.53 0.25 -2.12 0.08 0.12
BD153 -5.60 0.27 -5.14 0.00 0.01
BD154 -4.27 0.29 -3.79 0.01 0.02
Southern North Sea BDE28 -8.78 0.24 -8.39 0.00 0.00
BDE47 -4.49 0.23 -4.11 0.01 0.02
BDE66
BDE99 -4.20 0.28 -3.73 0.02 0.02
BD100 -2.14 0.24 -1.74 0.12 0.18
BD153 -5.28 0.27 -4.83 0.01 0.01
BD154 -3.95 0.24 -3.55 0.02 0.03
E Channel BDE28 -9.51 0.42 -8.82 0.00 0.00
BDE47 -5.36 0.38 -4.75 0.00 0.01
BDE66
BDE99 -4.76 0.40 -4.10 0.01 0.02
BD100 -2.77 0.38 -2.14 0.06 0.12
BD153 -5.96 0.41 -5.29 0.00 0.01
BD154 -4.43 0.40 -3.78 0.01 0.02
Irish Sea BDE28 -8.85 0.22 -8.48 0.00 0.00
BDE47 -4.65 0.19 -4.34 0.01 0.01
BDE66
BDE99 -3.99 0.21 -3.65 0.02 0.03
BD100 -1.98 0.19 -1.67 0.14 0.19
BD153 -5.15 0.20 -4.83 0.01 0.01
BD154 -3.34 0.19 -3.02 0.04 0.05
W Channel & Celtic Sea BDE47 -5.87 0.37 -5.25 0.00 0.01
BDE66
BDE99 -5.20 0.43 -4.50 0.01 0.01
BD100 -3.23 0.38 -2.61 0.04 0.07
BD153 -6.32 0.41 -5.64 0.00 0.00
BD154 -4.76 0.38 -4.13 0.01 0.02


Regional status compared to the Background Assessment Concentration (BAC)

The first 4 tabs show:

  • Regional status: estimates of the regional status (averaged over PBDEs) with pointwise upper one-sided 95% confidence intervals
  • Regional status by PBDE: regional status estimates for each PBDE with pointwise upper one-sided 95% confidence intervals plotted by PBDE
  • Regional status by region: regional status estimates for each PBDE with pointwise upper one-sided 95% confidence intervals plotted by region
  • 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:

  • blue: the mean concentration is significantly (p < 0.05) below the BAC
  • green: the mean concentration is significantly (p < 0.05) below the Federal Environmental Quality Guideline (FEQG)
  • orange: there is no FEQG and the mean concentration is not significantly below the BAC
  • red: the mean concentration is not significantly below the FEQG

The final 2 tabs show the estimates of the regional status (averaged over PBDEs) and the regional status trend by PBDE


  • Regional status
  • Regional status by PBDE
  • Regional status by region
  • Individual time series
  • Estimates by region
  • Estimates by region and PBDE





This table shows the estimates of the regional status:

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


biogeographic region status se upper concentration conc upper
Northern North Sea 2.28 0.53 3.16 9.80 23.48
Southern North Sea 2.68 0.53 3.54 14.54 34.63
E Channel 2.04 0.60 3.03 7.68 20.63
Irish Sea 2.76 0.51 3.61 15.85 36.98
W Channel & Celtic Sea 1.62 0.60 2.61 5.05 13.60


This table shows the estimates of the regional trend by determinand:

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


biogeographic region PBDE status se upper concentration conc upper
Northern North Sea BDE28 1.45 0.28 1.90 4.24 6.70
BDE47 4.53 0.21 4.88 92.65 131.59
BDE66 1.36 0.28 1.83 3.91 6.24
BDE99 1.08 0.28 1.55 2.94 4.69
BD100 3.20 0.25 3.61 24.55 37.00
BD153 1.53 0.27 1.98 4.62 7.23
BD154 2.83 0.29 3.31 16.98 27.27
Southern North Sea BDE28 1.75 0.24 2.14 5.73 8.47
BDE47 5.04 0.23 5.42 154.31 225.29
BDE66 1.78 0.24 2.17 5.93 8.78
BDE99 1.55 0.28 2.01 4.71 7.45
BD100 3.61 0.24 4.00 36.98 54.80
BD153 1.84 0.27 2.28 6.32 9.82
BD154 3.17 0.24 3.56 23.80 35.11
E Channel BDE28 1.03 0.42 1.71 2.80 5.55
BDE47 4.16 0.37 4.78 64.12 118.66
BDE66 1.17 0.42 1.86 3.21 6.39
BDE99 1.01 0.40 1.67 2.76 5.32
BD100 3.00 0.38 3.62 20.04 37.49
BD153 1.19 0.41 1.86 3.29 6.42
BD154 2.71 0.40 3.36 14.98 28.73
Irish Sea BDE28 1.65 0.22 2.01 5.22 7.46
BDE47 4.84 0.19 5.15 127.10 172.79
BDE66 1.63 0.20 1.96 5.09 7.10
BDE99 1.74 0.20 2.07 5.68 7.94
BD100 3.75 0.19 4.06 42.38 57.85
BD153 1.96 0.19 2.28 7.11 9.79
BD154 3.77 0.19 4.09 43.50 59.73
W Channel & Celtic Sea BDE47 3.65 0.37 4.26 38.43 70.93
BDE66 0.74 0.41 1.42 2.09 4.13
BDE99 0.57 0.42 1.27 1.77 3.56
BD100 2.52 0.37 3.14 12.47 23.08
BD153 0.82 0.41 1.50 2.28 4.49
BD154 2.37 0.38 3.00 10.73 20.11


PBDE profiles

The profile of concentrations across PBDEs can sometimes be useful for examining sources, and for comparing concentrations across regions where assessment criteria are not available. Profiles were examined by fitting the following linear mixed model by restricted maximum likelihood:

  • response: mean log concentration
  • fixed model: region
  • random model: PBDE + region.PBDE + station + station.PBDE + estimation variance + residual variation

where, for each time series, the mean log concentration is the estimated mean log concentration in the final monitoring year and the estimation variance is the variance associated with this estimate.

The estimated PBDE concentration profiles by region are shown below with pointwise 95% confidence limits. The units are ug/kg lw.