Thirteen individual organochlorine compounds at 3 concentrations (80, 400, and 2000 ng/mL culture medium), as well as mixtures, were assayed for the estrogen receptor (ER) activation or inhibition, using a luciferase reporter gene assay (RGA). None of the PCB 138, 153, or 180 or their mixture induced a response in the RGA.
The harbour porpoise (
Not all POPs released into the environment have the same bioaccumulation pattern in different species [
Public concern about environmental contamination by POPs increased recently because of many evidences showing that some of these compounds are xenoestrogens and interact with the endocrine system, resulting in numerous biological effects that may affect the health of humans and animals [
Currently, the United States Environmental Protection Agency (US-EPA) estimates that there are more than 87000 potential endocrine disrupters in the world. Nevertheless, developing methods to detect so many chemicals would take a massive financial mobilization. In this way, research on screening methods using short term bioassays to assess the risk of exposure to endocrine disrupting chemicals is needed [
In this context, the aim of this study was to measure the hormonal activity of North Sea harbour porpoise blubber samples and to identify the compounds that contribute to the hormonal activity of these samples. In order to associate hormonal activities to xenoestrogen contamination levels, the samples were analysed both by cell-based assays (reporter gene assays) and chemical analysis (mass spectrometry coupled to gas chromatography [GC-MS]). GC-MS combines high separation power with good identification capabilities, while reporter gene assays allow the measurement of the hormonal potency of samples [
The following equipment and materials have been used in this study: carbon dioxide (Air Liquide, Liège, Belgium); helium (Air Products, Brussels, Belgium); acetonitrile (Biosolve, Valkenswaard, Netherlands); luminometer Orion II (BRS, Drogenbos, Belgium); adenosine triphosphate (ATP), Dulbecco’s modified Eagle’s medium (DMEM), DMEM without red phenol, and fetal bovine serum and trypsin (Fisher Bioblock Scientific, Tournai, Belgium); Focus gas chromatograph and Polaris Q mass spectrometer (Interscience, Louvain-la-Neuve, Belgium); charcoal, dextran,
To obtain an estrogen-responsive cell line, MCF-7 human mammary tumour cells were stably transformed with a reporter vector containing the firefly luciferase gene under control of the vitellogenin promoter [
Blubber samples were obtained from 12 juvenile harbour porpoises (8 males and 4 females) stranded on the Belgian and French North Sea coasts between 2000 and 2003. These animals were necropsied by the Laboratory for Oceanology of the University of Liège according to standard procedures detailed elsewhere [
To separate POPs from blubber samples, we applied a solid-liquid extraction to extract fat with the POPs. This step was followed by an acid silica column chromatography to eliminate the fat. Using this method, we destroyed endogenous steroid hormones and their eventual conjugates, which were hydrolysed in presence of inorganic acids [
The extraction was performed as follows. One g of harbour porpoise blubber was homogenized in a test tube containing 2 mL of hexane using a glass stirring rod. The organic phase was separated and the hexane evaporated under nitrogen until dryness. Then, 0.25 g or 0.1 g of the extracted fat was solubilised in two different tubes containing 2 mL of hexane for the estrogen receptor- (ER-) mediated activity assays and GC-MS analyses, respectively. The fat solubilised in hexane was applied to a glass column, prewashed with hexane, filled (from the bottom to top) with 5 g of acid silica (40% H2SO4 w/w), 1 g of deactivated alumina, and 1 g of Na2SO4. POPs were eluted with a mixture of dichloromethane and hexane (1 : 3), the eluent was evaporated to dryness. The residue of the first tube was recovered in 25
The cell-based assays for estrogen receptor ER-mediated activity were carried out as follows. Ninety % confluent MCF-7-ERE cells were cultured at least 24 h in DMEM without phenol red (supplemented by 10% of FBS previously treated with charcoal-dextran), and they were released from the culture flask using 1.5 mL of trypsin (0.5 g/L). Then, cells were suspended in 10 mL of fresh culture medium and this suspension was diluted two times. One hundred
Analyses of extracts were performed using a Focus gas chromatograph coupled to a Polaris Q ion trap mass spectrometer. Helium was used as carrier gas at a flow rate of 1 mL/min. A volume of 2.0
|
Elution time (min) | Target compound |
---|---|---|
181/183 | 11.5–16.0 |
|
284/285 | 11.5–16.0 | HCB |
181/183 | 16.0–28.0 |
|
302/304 | 28.0–30.0 | PCB 80 13C |
235/237 | 30.0–31.4 |
|
316/318 | 30.0–31.4 |
|
235/237 | 31.4–33.3 |
|
360/362 | 31.4–33.3 | PCB 153 and PCB 138 |
394/396 | 33.3–36.0 | PCB 180 |
Cell-based assays for estrogen receptor- (ER-) mediated activity data were processed with Slide Write V6 software. Reference curves were fitted using the sigmoid dose-response curve equation:
Student’s
After exposing MCF-7-ERE cells to increasing concentrations of E2, sigmoid dose-response curves were obtained with an average coefficient of determination (
Dose-response curve of increasing concentrations of E2 (ng/mL culture medium). Data represent the mean ± S.D (
When applying the extraction and purification procedure to a mixture of 13 POPs, we noticed that 76 ± 3% of the initial estrogenic activity was recovered. As expected, a solution containing E2 showed no estrogenic activity after being submitted to the extraction/purification procedure, indicating that E2 was undoubtedly degraded by the acidified silica of the column. The procedure blank (negative control) showed a relative response of 7%, below the threshold of 17.6%, needed to evidence an estrogenic activity. This indicates that the extraction/purification method does not induce any estrogenic activity and is thus compatible with the reporter gene assay. Likewise, when E2 was added to the extract obtained from the procedure blank, MCF-7-ERE cells responded positively and in the expected intensity, confirming that the extraction and purification methods do not bring any inhibiting effect to the cells (data not shown).
For each selected compound, the maximum relative response was obtained at the concentration of 2000 ng/mL culture medium (Table
Estrogen receptor-mediated luciferase expression (measured as light emission) observed in MCF-7-ERE cells exposed during 24 hours to single compounds or mixtures of selected POPs. All mixtures contained the same weight proportion of the constituents to achieve the concentration of 80 ng/mL, 400 ng/mL, or 2000 ng/mL medium (
Relative response (%)a | EEQ (ng/mL)b | |||||
---|---|---|---|---|---|---|
80 ng/mL | 400 ng/mL | 2000 ng/mL | 80 ng/mL | 400 ng/mL | 2000 ng/mL | |
PCB 138 | <LOQ | <LOQ | <LOQ | n/a | n/a | n/a |
PCB 153 | <LOD | <LOD | <LOQ | n/a | n/a | n/a |
PCB 180 | <LOD | <LOD | <LOD | n/a | n/a | n/a |
Mixture of PCB congeners (1) | <LOD | <LOD | <LOQ | n/a | n/a | n/a |
|
||||||
|
28 ± 0 | 67 ± 3 | 72 ± 7 | 2.1 ± 0.0 × 10−3 | 7.6 ± 0.8 × 10−3 | 9.4 ± 2.4 × 10−3 |
|
<LOD | 29 ± 3 | 66 ± 3 | n/a | 2.1 ± 0.2 × 10−3 | 7.3 ± 0.6 × 10−3 |
|
<LOD | <LOQ | 36 ± 2 | n/a | n/a | 2.8 ± 0.2 × 10−3 |
|
<LOD | <LOQ | 32 ± 2 | n/a | n/a | 2.4 ± 0.2 × 10−3 |
|
<LOD | <LOQ | 21 ± 1 | n/a | n/a | 1.5 ± 0.0 × 10−3 |
Mixture of DDT and its metabolites (2) | <LOQ | 26 ± 1 | 49 ± 4 | n/a | 1.9 ± 0.1 × 10−3 | 4.3 ± 0.5 × 10−3 |
|
||||||
|
<LOQ | 35 ± 2 | 64 ± 4 | n/a | 2.7 ± 0.1 × 10−3 | 6.8 ± 1.0 × 10−3 |
|
<LOQ | <LOQ | 20 ± 3 | n/a | n/a | 1.4 ± 0.2 × 10−3 |
|
<LOD | <LOQ | <LOQ | n/a | n/a | n/a |
|
<LOD | <LOQ | <LOQ | n/a | n/a | n/a |
HCB | <LOD | <LOD | <LOD | n/a | n/a | n/a |
Mixture of HCH isomers and HCB (3) | <LOQ | <LOQ | 23 ± 1 | n/a | n/a | 1.7 ± 0.1 × 10−3 |
|
||||||
Mixture (1) + (2) | <LOQ | 32 ± 1 | 52 ± 2 | n/a | 2.4 ± 0.1 × 10−3 | 4.7 ± 0.3 × 10−3 |
Mixture (1) + (3) | <LOQ | <LOQ | 28 ± 2 | n/a | n/a | 2.1 ± 0.2 × 10−3 |
Mixture (2) + (3) | <LOQ | 20 ± 7 | 54 ± 2 | n/a | 1.5 ± 0.5 × 10−3 | 5.0 ± 0.3 × 10−3 |
Mixture (1) + (2) + (3) | <LOQ | 27 ± 1 | 54 ± 2 | n/a | 2.0 ± 0.1 × 10−3 | 5.0 ± 0.3 × 10−3 |
aThe maximal response observed for E2 was arbitrarily set to 100% and the responses observed for the chemicals and mixtures are expressed in percentage of the maximal response (relative response).
bEstradiol equivalents were determined by linear extrapolation from calibration curves obtained after exposure to E2 and are expressed in ng/mL culture medium.
n/a: not applicable.
In order to detect a possible interaction between the chemicals mentioned before, MCF-7-ERE cells were also exposed to mixtures containing the same weight proportion of each molecule included in the mixture to reach a final concentration of 80 ng/mL, 400 ng/mL, or 2000 ng/mL culture medium for the sum of all compounds. The mixture of the 3 PCBs (mixture #1) did not activate the estrogen receptor. The most concentrated mixture of DDT and its metabolites (mixture #2, 2000 ng/mL) contains each congener at a concentration of 400 ng/mL, at which only
None of the selected chemicals showed antiestrogenic activity. Conversely,
Three NDL-PCB congeners (PCB 138, PCB 153, and PCB 180), four HCH isomers (
Chromatogram of a mixture of 13 standard solutions of target pollutants.
Among the chemicals analysed, the PCBs were the main contaminants in North Sea harbour porpoise blubber, followed by the DDT group and finally by the isomers of HCH and HCB (Table
Gender, length (cm), weight (kg), blubber thickness (cm), and blubber levels (
03/1521 | 01/1196 | 03/1238 | A00/1140 | A00/258 | A03/1517 | 01/847 | 01/805 | 01/1219 | A00/600 | 01/887 | A00/974 | Average | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Gender | M | M | F | F | M | M | F | M | M | M | M | F | — |
Length | 117 | 104 | 127 | 112 | 108 | 128 | 114 | 99 | 112 | 103 | 110 | 114 | 112 ± 9 |
Weight | 30 | n/a | 26 | 20 | 18 | 22 | 29 | 14 | 19 | 27 | 17 | 22 | 22 ± 5 |
Blubber thickness | 20 | 22 | 10 | 13 | 10 | 8 | 20 | 5 | 8 | 40 | 6 | 20 | 15 ± 10 |
Emaciation | n/a | n/a | Yes | Yes | Yes | Yes | No | Yes | Yes | No | Yes | No | — |
Parasites | n/a | n/a | Yes | Yes | Yes | Yes | No | No | Yes | No | Yes | No | — |
|
|||||||||||||
PCB 138 | 9.9 × 102 | 1.3 × 103 | 8.3 × 103 | 3.8 × 103 | 3.7 × 103 | 3.1 × 104 | 2.7 × 103 | 3.7 × 103 | 7.7 × 103 | 3.6 × 103 | 2.3 × 103 | 5.9 × 102 | 5.8 ± 8.3 × 103 |
PCB 153 | 1.4 × 103 | 1.7 × 103 | 1.2 × 104 | 6.3 × 103 | 5.5 × 103 | 4.2 × 104 | 4.0 × 103 | 5.5 × 103 | 1.1 × 104 | 5.1 × 103 | 3.2 × 103 | 6.0 × 102 | 0.8 ± 1.1 × 104 |
PCB 180 | 3.3 × 102 | 3.2 × 102 | 2.5 × 103 | 1.8 × 103 | 1.2 × 103 | 7.4 × 103 | 8.0 × 102 | 1.2 × 103 | 1.9 × 103 | 9.3 × 102 | 7.9 × 102 | 1.1 × 102 | 1.6 ± 1.9 × 103 |
|
2.7 × 103 | 3.3 × 103 | 2.3 × 104 | 1.2 × 104 | 1.0 × 104 | 8.1 × 104 | 7.5 × 103 | 1.0 × 104 | 2.1 × 104 | 9.6 × 103 | 6.3 × 103 | 1.3 × 103 | 1.6 ± 2.2 × 104 |
|
|||||||||||||
|
4.8 × 101 | 1.0 × 102 | 3.4 × 102 | 9.8 × 101 | 7.4 × 101 | 2.1 × 102 | 6.0 × 101 | 8.2 × 101 | 8.6 × 102 | 5.4 × 101 | 1.7 × 102 | 7.1 × 101 | 1.8 ± 2.3 × 102 |
|
n/d | 7.2 × 101 | 1.8 × 102 | 7.8 × 101 | 6.8 × 101 | 4.1 × 102 | n/d | 8.6 × 101 | 5.2 × 102 | n/d | 6.9 × 101 | 4.0 × 101 | 1.7 ± 1.8 × 102 |
|
1.8 × 102 | 3.2 × 102 | 7.9 × 102 | 5.6 × 102 | 4.7 × 102 | 7.1 × 102 | 1.9 × 102 | 3.7 × 102 | 1.4 × 103 | 2.0 × 102 | 5.8 × 102 | 1.1 × 102 | 4.9 ± 3.6 × 102 |
|
3.4 × 102 | 5.3 × 102 | 8.9 × 102 | 9.2 × 102 | 8.5 × 102 | 1.2 × 103 | 2.4 × 102 | 7.3 × 102 | 2.6 × 103 | 4.1 × 102 | 6.0 × 102 | 1.4 × 102 | 7.9 ± 6.6 × 102 |
|
1.0 × 103 | 1.2 × 103 | 3.1 × 103 | 2.6 × 103 | 2.9 × 103 | 4.1 × 103 | 9.1 × 102 | 2.4 × 103 | 8.6 × 103 | 1.4 × 103 | 2.3 × 103 | 5.1 × 102 | 2.6 ± 2.2 × 103 |
|
1.6 × 103 | 2.3 × 103 | 5.3 × 103 | 4.3 × 103 | 4.4 × 103 | 6.6 × 103 | 1.4 × 103 | 3.7 × 103 | 1.4 × 104 | 2.1 × 103 | 3.7 × 103 | 8.6 × 102 | 4.2 ± 3.5 × 103 |
|
|||||||||||||
|
n/d | n/d | 9.7 × 101 | n/d | 8.8 × 101 | 8.0 × 101 | n/d | 8.3 × 101 | 1.3 × 102 | 4.2 × 101 | 7.4 × 101 | 4.7 × 101 | 8.0 ± 2.7 × 101 |
|
n/d | n/d | n/d | n/d | n/d | n/d | n/d | n/d | n/d | n/d | n/d | n/d | — |
|
9.8 × 101 | 1.4 × 102 | 1.3 × 102 | 1.3 × 102 | 2.4 × 102 | 2.0 × 102 | 8.0 × 101 | 1.7 × 102 | 4.8 × 102 | 1.7 × 102 | 1.5 × 102 | 1.2 × 102 | 1.8 ± 1.1 × 102 |
|
7.0 × 101 | n/d | 6.8 × 101 | 6.6 × 101 | n/d | n/d | n/d | 8.0 × 101 | 9.8 × 101 | 7.1 × 101 | 1.0 × 102 | 7.4 × 101 | 7.9 ± 1.4 × 101 |
HCB | 1.4 × 102 | 2.1 × 102 | 5.4 × 102 | 2.2 × 102 | 3.1 × 102 | 4.9 × 102 | 1.3 × 102 | 3.4 × 102 | 1.5 × 103 | 9.8 × 101 | 6.0 × 102 | 7.6 × 101 | 3.9 ± 4.0 × 102 |
|
3.1 × 102 | 3.5 × 102 | 8.4 × 102 | 4.2 × 102 | 6.3 × 102 | 7.7 × 102 | 2.1 × 102 | 6.7 × 102 | 2.2 × 103 | 3.9 × 102 | 9.3 × 102 | 3.1 × 102 | 6.7 ± 5.4 × 102 |
|
|||||||||||||
|
4.6 × 103 | 5.9 × 103 | 2.9 × 104 | 1.7 × 104 | 1.5 × 104 | 8.8 × 104 | 9.1 × 103 | 1.5 × 104 | 3.7 × 104 | 1.2 × 104 | 1.1 × 104 | 2.5 × 103 | 2.1 ± 2.4 × 104 |
n/d: not detected; n/a: not available.
The agonistic and antagonistic activity mediated by the estrogen receptor (ER) elicited by North Sea harbour porpoise blubber samples in MCF-7-ERE cells is reported in Figures
Estrogen receptor- (ER-) mediated agonistic activity elicited by 12 North Sea harbour porpoise blubber samples in MCF-7-ERE cells. The horizontal dashed line represents the response of the procedure blank. Results are expressed as percent of the maximal response induced by E2 (columns) or as
Estrogen receptor- (ER-) mediated antagonistic activity elicited by North Sea harbour porpoise blubber samples (
From GC-MS data of sample contamination (Table
Concentrations (ng/mL) of 13 organochlorine compounds in the extracts of 12 samples of North Sea harbour porpoise blubber, in culture medium solution to which the ER sensitive cells were exposed in the cell based assay (calculated from GC-MS data from Table
03/1521 | 01/1196 | 03/1238 | A00/1140 | A00/258 | A03/1517 | 01/847 | 01/805 | 01/1219 | A00/600 | 01/887 | A00/974 | |
---|---|---|---|---|---|---|---|---|---|---|---|---|
PCB 138 | 4.0 × 101 | 5.2 × 101 | 3.3 × 102 | 1.5 × 101 | 1.5 × 102 | 1.3 × 103 | 1.1 × 102 | 1.5 × 102 | 3.1 × 102 | 1.4 × 102 | 9.1 × 101 | 2.4 × 101 |
PCB 153 | 5.4 × 101 | 6.7 × 101 | 4.9 × 102 | 2.5 × 102 | 2.2 × 102 | 1.7 × 103 | 1.6 × 102 | 2.2 × 102 | 4.5 × 102 | 2.1 × 102 | 1.3 × 102 | 2.4 × 101 |
PCB 180 | 1.3 × 101 | 1.3 × 101 | 1.0 × 102 | 7.3 × 101 | 4.7 × 101 | 3.0 × 102 | 3.2 × 101 | 4.9 × 101 | 7.5 × 101 | 3.7 × 101 | 3.1 × 101 | 4.5 × 100 |
Σ (3) PCBs | 1.1 × 102 | 1.3 × 102 | 9.2 × 102 | 4.8 × 102 | 4.2 × 102 | 3.2 × 103 | 3.0 × 102 | 4.2 × 102 | 8.4 × 102 | 3.9 × 102 | 2.5 × 102 | 5.2 × 101 |
|
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|
1.9 × 100 | 4.2 × 100 | 1.4 × 101 | 3.9 × 100 | 3.0 × 100 | 8.5 × 100 | 2.4 × 100 | 3.3 × 100 | 3.4 × 101 | 2.2 × 100 | 6.7 × 100 | 2.8 × 100 |
|
n/a | 2.9 × 100 | 7.2 × 100 | 3.1 × 100 | 2.7 × 100 | 1.7 × 101 | n/a | 3.4 × 100 | 2.1 × 101 | n/a | 2.8 × 100 | 1.6 × 100 |
|
7.2 × 100 | 1.3 × 101 | 3.2 × 101 | 2.2 × 101 | 1.9 × 101 | 2.8 × 101 | 7.5 × 100 | 1.5 × 101 | 5.6 × 101 | 8.0 × 100 | 2.3 × 101 | 4.3 × 100 |
|
1.4 × 101 | 2.1 × 101 | 3.5 × 101 | 3.7 × 101 | 3.4 × 101 | 5.0 × 101 | 9.5 × 100 | 2.9 × 101 | 1.0 × 102 | 1.6 × 101 | 2.4 × 101 | 5.6 × 100 |
|
4.2 × 101 | 5.0 × 101 | 1.2 × 102 | 1.1 × 102 | 1.2 × 102 | 1.6 × 102 | 3.6 × 101 | 9.6 × 101 | 3.4 × 102 | 5.6 × 101 | 9.3 × 101 | 2.0 × 101 |
|
6.4 × 101 | 9.1 × 101 | 2.1 × 102 | 1.7 × 102 | 1.8 × 102 | 2.7 × 102 | 5.6 × 101 | 1.5 × 102 | 5.6 × 102 | 8.2 × 101 | 1.5 × 102 | 3.5 × 101 |
|
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|
n/a | n/a | 3.9 × 100 | n/a | 3.5 × 100 | 3.2 × 100 | n/a | 3.3 × 100 | 5.0 × 100 | 1.7 × 100 | 3.0 × 100 | 1.9 × 100 |
|
n/a | n/a | n/a | n/a | n/a | n/a | n/a | n/a | n/a | n/a | n/a | n/a |
|
3.9 × 100 | 5.8 × 100 | 5.3 × 100 | 5.1 × 100 | 9.4 × 100 | 7.8 × 100 | 3.2 × 100 | 6.9 × 100 | 1.9 × 101 | 7.0 × 100 | 6.1 × 100 | 4.6 × 100 |
|
2.8 × 100 | n/a | 2.7 × 100 | 2.6 × 100 | n/a | n/a | n/a | 3.2 × 100 | 3.9 × 100 | 2.8 × 100 | 4.2 × 100 | 3.0 × 100 |
HCB | 5.7 × 100 | 8.4 × 100 | 2.1 × 101 | 8.9 × 100 | 1.2 × 101 | 2.0 × 101 | 5.4 × 100 | 1.3 × 101 | 6.1 × 101 | 3.9 × 100 | 2.4 × 101 | 3.0 × 100 |
|
1.2 × 101 | 1.4 × 101 | 3.3 × 101 | 1.7 × 101 | 2.5 × 101 | 3.1 × 101 | 8.6 × 100 | 2.7 × 101 | 8.9 × 101 | 1.5 × 101 | 3.7 × 101 | 1.3 × 101 |
|
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|
1.9 × 102 | 2.4 × 102 | 1.2 × 103 | 6.7 × 102 | 6.2 × 102 | 3.5 × 103 | 3.7 × 102 | 5.9 × 102 | 1.5 × 103 | 4.8 × 102 | 4.4 × 102 | 9.9 × 101 |
|
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Activity recorded in the ER reporter gene assay (% of relative response) | None | Antiestrogenic (7%) | Antiestrogenic (16%) | Antiestrogenic (6%) | Estrogenic (22%) | Antiestrogenic (13%) | Antiestrogenic (5%) | None | Estrogenic (24%) and antiestrogenic (6%) | Antiestrogenic (5%) | None | Antiestrogenic (7%) |
n/a: not applicable.
As previously shown, pollutants from the DDT group presented higher estrogenic activities than the other POPs assessed. Moreover, the most potent agonist blubber samples (A00/258 and 01/1219) presented lower
The most contaminated sample (A03/1517), containing a total of more than 88 mg organochlorine/kg fat, displayed a slight antiestrogenic effect. This can be easily explained by the high contribution of PCBs (more than 81 mg/kg), which were not inducing any response in the estrogen-responsive cells.
The study of estrogen receptor- (ER-) mediated activity of POPs in MCF-7-ERE cells showed that several organochlorine pollutants (DDT and metabolites and HCH isomers) present an estrogenic activity, which was also confirmed by other authors [
Concentrations of organochlorine chemicals found in North Sea harbour porpoise blubber samples are comparable with data formerly published [
Metabolites play a dominant role if their persistence exceeds that of the parent product. Even though DDT was banned from utilisation in North America and Western Europe in the 1970s with no new input in the southern North Sea during the last decades [
The high concentration of
The large difference of contamination level between samples is probably due to a possible difference in health conditions (e.g., disease or parasitic infection) of the animals, as reported by Pierce et al. [
The analyses of blubber samples by cell-based bioassays suggest that POPs measured by GC-MS in this study cannot justify alone the estrogenicity of the extracts and that other endocrine disrupters contaminate the porpoises. Interestingly, the sample showing the highest estrogenic activity and the two samples displaying the highest ER antagonistic activities are among the most contaminated samples. It can be expected that these samples, with a high load of contaminants, also contain other POPs than the 13 organochlorine measured in this study, among which some are agonist or antagonist of the estrogen receptor, such as dioxins and furans [
Our study permitted the analysis of harbour porpoise blubber samples both by chemical analysis and cell-based assays, providing consistent data including the level of contamination and the (anti-) estrogenic activity of these samples. Within each group of studied substances, PCB 153,
High load persistent organic pollutants in porpoise blubber samples indicate that these pollutants can also be found in food from the North Sea, and the hormonal activity measured in some samples confirms the presence of endocrine disrupting chemicals in the marine environment.
The authors declare that there is no conflict of interests regarding the publication of this paper.