Journal of Exposure Science and Environmental Epidemiology (2012) 22, 93–100
r 2012 Nature America, Inc. All rights reserved 1559-0631/12
www.nature.com/jes
Biological analysis of endocrine-disrupting chemicals in animal meats
from the Pearl River Delta, China
ALICE YU SHEUNG LAWa, XI WEIa, XIAOWEI ZHANGb,c, NAK KI MAKa, KWAI CHUNG CHEUNGa,
MING HUNG WONGa, JOHN PAUL GIESYb,c,d,e,f AND CHRIS KONG CHU WONGa
a
Department of Biology, Croucher Institute of Environmental Sciences, Hong Kong Baptist University, Kowloon, Hong Kong, SAR, China
Department of Veterinary Biomedical Sciences & Toxicological Center, University of Saskatchewan, Saskatchewan, Canada
c
School of Environment, Nanjing University, Nanjing, China
d
Department of Zoology, and Center for Integrative Toxicology, Michigan State University, East Lansing, Michigan, USA
e
Department of Biology & Chemistry, City University of Hong Kong, Kowloon, Hong Kong, SAR, China
f
Department of Zoology, College of Science, King Saud University, Riyadh, Saudi Arabia
b
Endocrine disrupting chemicals (EDCs) consist of a diverse group of industrial chemicals and pharmacological agents. The use of instrumental analyses as
the first screening tool might not be cost-effective to identify the existence of enormous numbers of chemical contaminants in environments. Also,
knowledge of the concentration of individual residues is difficult to use to evaluate biological impacts of contaminants to wildlife and humans. The
primary objective of the present study was to develop and to test the feasibility of using a battery of exposure biomarkers for the rapid-screening of various
endocrine disrupting activities present in food. The measurement of the EDC-elicited activities involved various (i) receptor-mediated responses, including
androgenic, estrogenic, dioxin-like, glucocorticoid-like, progesterone-like, peroxisome proliferator-like and retinoid-like as well as (ii) the non-receptor
mediated responses through modulation of cellular reactive oxygen species (ROS) and ATP content. Samples of both local and imported pork, beef and
chicken as well as freshwater and seawater fishes were collected. Extracts of different foods exhibited various dioxin-like and ‘‘hormonal’’ activities. Fish
and chicken skin were found to be the major source of exogenous ‘‘hormonal’’ and dioxin-like substances in diets. Extracts of beef and pork contained
lesser potencies of hormonally-active agents. Our data suggest that the proposed EDC-screening platform may be useful in a risk assessment for the
routine monitoring of EDCs in foods. Continuous monitoring and research is warranted to assess the physiological consequences of the consumption.
Journal of Exposure Science and Environmental Epidemiology (2012) 22, 93–100; doi:10.1038/jes.2011.36; published online 12 October 2011
Keywords: luciferase reporter assays, dioxin, hormones, market basket, toxicity, diet.
Introduction
It has been almost 200 years since the industrial revolution
started in United Kingdom and European countries. During
this period, an enormous number of synthetic chemicals with
diverse structural features have been produced for industrial,
medical and domestic purposes. Recently, the European
Union reported that the first set of registered chemical
substances contains over 140,000 substances (Judson et al.,
2009). Those chemical substances, originally thought to have
little or no biological toxicity, are widely utilized in our daily
lives and food products. Not until the first World Wildlife
Federation Wingspread Conference held in 1994 were
concerns about the endocrine disrupting (ED) effects of these
1. Address all correspondence to: Professor Chris Kong Chu Wong,
Department of Biology, Croucher Institute of Environmental Sciences,
Hong Kong Baptist University, Kowloon Tong, Hong Kong, SAR, China.
Tel: þ 852 3411 7053. Fax: þ 852 3411 5995.
E-mail: ckcwong@hkbu.edu.hk
Received 23 November 2010; accepted 17 July 2011; published online 12
October 2011
chemicals articulated (Colborn et al., 1993; Soto et al., 2009).
Since then, considerable numbers of studies have been
conducted to reveal the health effects of ED chemicals
(EDCs). The U.S. Environmental Protection Agency (EPA)
has defined EDCs as exogenous agents that can interfere with
the synthesis, metabolism and action of endogenous hormones
(Kavlock et al., 1996). With the benefit of hindsight, the ED
effects of environmental chemical contaminants have been
shown to impose long-term effect on animal health and
development (Anway et al., 2005; Dolinoy et al., 2007;
Leranth et al., 2008). Although the regulation on the
‘‘hormonal growth-promoting’’ agents in food producing
animals has been enforced (Stephany, 2010), the major focus
is on the testing of exogenous estrogenic chemicals (Stokes,
2004). Other EDC-elicited hormonal activities (but not limited
to), androgenic, estrogenic, dioxin-like, glucocorticoid-like,
progesterone-like, peroxisome proliferator-like and retinoidlike activities, have not been adopted in a practical
screening approach (Phillips and Foster, 2008; Phillips et al.,
2008).
Most of the EDCs are ubiquitous and the possible routes
of human exposure to EDCs are from the environments,
Law et al.
consumer products and foods (Poppenga, 2000; Feron et al.,
2002; Mantovani et al., 2006; Wigle et al., 2008). Among
these routes, the most important pathway for human
exposure to EDCs is via food consumption (Liem et al.,
2000), contributing over 90% of total exposure in one’s
lifetime. Owing to the large number of EDCs of heterogeneous structures, it is impractical to use chemical-analytical
approaches as the first screening tool to monitor their levels in
the high-volume consumer products (Judson et al., 2009).
Hence in the present study, a battery of bioassays was used to
screen food for both receptor-mediated and non-receptormediated EDCs. Local and imported animal meats, such as
chicken, pork and beef, and fish, were collected for the
detection of the residual ‘‘hormonal’’ and dioxin-like
activities, as well as the biological activities related to the
disturbance of cellular oxidative stress and energy levels.
Materials and methods
Food Sample Preparation
Samples of meats were purchased from local markets in
Hong Kong. For each type of meat, at least three individual
samples were collected. For chicken wing, skin or meat were
dissected and were analyzed separately. All samples were
freeze-dried and extracted as described previously (Cheung
et al., 2007). Briefly the freeze-dried sample (3 g) was mixed
with 50 ml of dichloromethane:acetone (1:1), and was
Soxhlet extracted in a shaking incubator (JULABO Labortechnik, GMBH, Seelbach, West Germany) at 40 1C for
18 h. The organic phase was collected and was then
concentrated using a rotary evaporator (BÜCHI) at 60 1C
until 2 ml of solution was left. The solution was cleaned up
using a micro-florisil column with 10 ml of dichloromethane:hexane (1:1) as an elutant. The solution was then
evaporated with a gentle stream of nitrogen until 5 ml of
solvent was obtained. Of which 1 ml of the solution was used
for fat content measurement by solvent evaporation until a
constant weight was obtained. The rest of the 4 ml aliquant
was further cleaned up by a gel permeation chromatography
(GPC, Gilson, USA) to remove residual fat tainted in the
solvent. A total of 600 ml of the extract was transferred into a
vial and was evaporated to dryness under stream of nitrogen.
Samples were re-dissolved in 100 ml of dimethylsulfoxide
(DMSO, Sigma, St Louis, MO, USA) and were then used in
different bioassays.
3-(4, 5-Dimethyl-2-thiazolyl)-2, 5-diphenyl-2Htetrazolium Bromide (MTT) Assay
The human nasopharyngeal carcinoma cell line, CNE2 and
the human breast cancer cell line, MCF7 were grown in
RPMI-1640 supplemented with 10% FBS (HyClone,
Perbio, Thermo Fisher Scientific, Cramlington, UK) and
antibiotics (50 U/ml penicillin and 50 mg/ml streptomycin)
94
Biological analysis of EDCs in food
(Invitrogen, Carlsbad, CA, USA). For the MTT assay,
CNE2 cells were plated in triplicate into 96-well plates
(Iwaki, Tokyo, Japan) at a density reaching 70–80%
confluence by the time of adding the food extracts. After
24 h incubation with the extracts in 5% CO2 at 37 1C, the
cells were incubated with 250 mg/ml MTT (Sigma) for
another 3 h for the development of coloration, blue
formazan. The medium was then removed, and the blue
formazan was dissolved in 100 ml of DMSO. Optical density
(OD) was measured at 570 nm with a micro-plate reader
(BioTek, Winooski, USA).
ATP Assay
CNE2 cells were plated in triplicate into 24-well plates
(Iwaki) at a density reaching 70–80% confluence by the time
of adding the food extracts. After 24 h incubation with the
extracts, the cells were lysed in a passive lysis buffer
(Promega, Madison, WI, USA). After centrifugation at
10,000 g for 2 min, 10 ml of the supernatant were used to
measure cellular ATP levels using an ATP determination kit
according to the manufacturer’s instruction (Molecular
Probes, Invitrogen). Luciferin-luciferase luminescence was
measured by a multilabel reader VICTOR X4 (PerkinElmer,
Waltham, MA, USA).
Detection of Intracellular Reactive Oxygen Species (ROS)
CNE2 cells were plated in triplicate into 96-well plates. After
24 h incubation with the extracts, ROS was measured by an
incubation of the cells with 10 mM H2DCF-DA (Molecular
Probes, Invitrogen) for 30 min. DCF fluorescence was
measured at Ex495 nm/Em530 nm using the multilabel reader
VICTOR X4.
Reporter Plasmids
The human androgen responsive element (ARE), dioxin
responsive element (DRE) and glucocorticoid responsive
element (GRE) luciferase reporters were constructed
from human IGF-1 promoter (-1426/-1294), human
CYP1A1 promoter (-1392/-874) and human gilz promoter
(-1940/-1525), respectively. The IGF-1 promoter fragment
contains two AREs, the CYP1A1 promoter segment
contains five DREs, whereas the gilz promoter segment
contains four GREs. The respective promoters were
amplified by a high-fidelity Taq DNA polymerase (Invitrogen) using respective primers (Table 1) and human genomic
DNA (Roche, USA). The PCR products were purified
using a gel extraction kit according to the manufacturer’s
instruction (Qiagen, Valencia, CA, USA). The sequences of
the PCR products were verified by DNA sequencing
(Tech Dragon, Hong Kong), and were then cloned into
pGL3-SV40 vector (Promega). A human estrogen receptor-a
(ERa) and a human estrogen responsive element (ERE)
reporter gene, pGL2-ERE-luc were gifts from Dr. Calvin Lee
(University of Hong Kong). The human androgen receptor
Journal of Exposure Science and Environmental Epidemiology (2012) 22(1)
Law et al.
Biological analysis of EDCs in food
Table 1. Primers used for the amplification of regions of ARE, DRE and GRE from the upstream respected human gene promoter.
Construct
Human promoter
Forward primer (50 -30 )
Reverse primer (50 -30 )
pGL3-ARE-SV40
pGL3-DRE-SV40
pGL3-GRE-SV40
IGF-1
CYP1A1
gilz
GGGCACATAGTAGAGCTCACAAAATG
CCGGCTAGCTTGCGTGCGCC
GTGCAGAGGGCAAATTAATA
TGAGTCTTCTGTGTGGTTAATACATTG
GCCAGGTTGAGCTAGGCACGCAAAT
CAAATGCAGTCTGAAGGCCT
(AR) was developed at the University of Saskatchewan.
Reporter constructs for human progesterone responsive
element (PRE), retinoic acid receptor response element
(RARE), peroxisome proliferator-activated receptor gamma
(PPARg) responsive element (PPRE) were purchased from
Addgene, USA.
Reporter Assay
The day before transfection, MCF7 or CNE2 cells were
plated into 24-well tissue culture dishes at a density reaching
70–80% confluence by the time of transfection. Transfection
was performed using LipofectAMINE 2000 reagent (Invitrogen) and OPTI-MEM I medium, (GIBCO, USA) with
250 ng of reporter of interest. The luciferase construct was
cotransfected with an internal control, 15 ng of pRL-SV40
plasmid (Promega) to normalize the transfection efficiency.
Six hours after transfection, the transfection medium was
replaced by a complete medium (phenol-red free RPMI-1640
medium with 10% charcoal-striped serum), and the food
extracts was added. The culture was then incubated for 24 h
in 5% CO2 at 37 1C. The cells were then lysed in the passive
lysis buffer. After centrifugation, 20 ml of the supernatant
were used to measure the luciferase activities. Firefly and
Renilla luciferase activities were sequentially measured from a
same sample using the Dual-Luciferase reporter assay system
(Promega) and the multilabel reader VICTOR X4.
Statistical Analysis
Drugs treatments were performed in triplicate in the same
experiments and individual experiments were repeated at least
three times. All data are represented as the mean±SEM.
Statistical significance was assessed with a Student’s t-test or
one-way analysis of variance (ANOVA) followed by
Duncan’s multiple range test. Groups were considered
significantly different if Po0.05.
Results and discussion
Strategy for the Screening of EDC Contamination in
Common Food Items
EDCs can directly and/or indirectly alter the normal
functions of endocrine system in vertebrates, leading to the
disturbances of reproduction, growth and development
(Sanderson 2006; Diamanti-Kandarakis et al., 2009, 2010).
Journal of Exposure Science and Environmental Epidemiology (2012) 22(1)
Cell Viability Assay (MTT)
Pre-screening
Redox/Cellular ATP Levels
Endocrine
Endocrine Disruptors
Disruptors
Prescreening
Prescreening
GRE
Luciferase
ARE
Luciferase
PRE
PRE
Luciferase
Luciferase
DRE
DRE
Luciferase
Luciferase
ERE
ERE
Luciferase
Luciferase
PPRE
PPRE
Luciferase
Luciferase
RARE
RARE
Luciferase
Luciferase
Analysis
Analysis
Figure 1. The flow chart indicates the strategy of using a battery of
bioassays to detect non-receptor and receptor-mediated activities.
There has been increasing concern on the roles of EDCs in
the etiology of metabolic diseases and cancer (DiamantiKandarakis et al., 2009; Soto et al., 2009; Swedenborg et al.,
2009; Soto and Sonnenschein, 2010). To safeguard the
public health, instrumental chemical analysis has been
adopted globally for assessing the risk of human exposure
to EDCs and their metabolites (Hotchkiss et al., 2008).
However, in view of the large inventories of man-made
chemicals, the chemical-analytical approach cannot be used
as a high-throughput screening tool to elucidate the presence
of both known and unknown chemical contaminants (Judson
et al., 2009). In addition the possible ‘‘biological’’ activities of
the EDCs might not be revealed (Wei et al., 2010). In the
present study, we aimed to illustrate the work plan of using a
battery of bioassays to apply for the high-throughput
screening of EDC contamination in daily food basket
(Figure 1).
Before identification of cellular responses to the sample
extracts, the possible cytotoxic effects were assessed by MTT
assay. The purpose of the assay is to evaluate if the sample
extracts contained chemicals that can cause cell death
95
Law et al.
Biological analysis of EDCs in food
directly, as this would considerably affect the accuracy of the
subsequent bioassays.
In this study, a total of 84 samples were collected including
pork, beef, chicken and fish, supplied from different countries
of origin, such as North America, Brazil, China and Hong
Kong. No cytotoxicity was observed for any of the sample
extracts (Figures 2a and 3a). In the absence of cytotoxicity,
non-specific (i.e., cellular ROS/ATP levels) and specific
MTT assay
a
Beef
Chicken
Skin
0.5
OD 490 nm
0.4
Pork
Meat
a
a
a
a
a
a
H
A
a
a
a
a
C
H
A
a
a
a
a
a
C
H
A
B
a
a
0.3
0.2
0.1
0.0
Ctrl
B
C
B
B
H
A
ATP assay
b
Beef
Chicken
Skin
5
4
µM/ mg protein
C
a
a
Pork
Meat
a
a
a
C
H
A
a
a
a
a
a
a
a
a
C
H
A
B
C
H
A
a
a
a
C
H
a
3
2
1
0
Ctrl
B
B
B
A
ROS assay
c
Chicken
Skin
a
4.0
Beef
Pork
Meat
DCF fluorescence
b
3.0
c
c
c
d
c
d
d
d
2.0
d
d
d
d
d
d
d
H
A
B
C
H
A
1.0
0.0
Ctrl
B
C
H
A
B
C
H
A
B
C
B – Brazil
C – China
H – Hong Kong
A – America
Figure 2. The effects of beef, pork, chicken meat & skin extracts on (a) cell viability, (b) cellular ATP and (c) ROS levels.
96
Journal of Exposure Science and Environmental Epidemiology (2012) 22(1)
Law et al.
Biological analysis of EDCs in food
MTT assay
0.4
a
a
a
a
a
a
OD 490 nm
0.3
0.2
0.1
0.0
Ctrl
GC
SS
OS
BE
BF
ATP assay
5
a
µM/ mg protein
4
a
a
a
a
a
3
2
1
0
Ctrl
GC
SS
OS
BE
BF
ROS assay
a
a
a
a
DCF fluorescence
2.0
a
a
1.5
1.0
0.5
0.0
Ctrl
GC
SS
OS
BE
BF
GC- Grass Carp
SS- Spotted Snakehead
OS- Orange-spotted grouper
BE- Bigeye
BF- Bartail Flathead
Figure 3. The effects of fish meat extracts on (a) cell viability, (b)
cellular ATP and (c) ROS levels.
Journal of Exposure Science and Environmental Epidemiology (2012) 22(1)
responses (i.e., ‘‘hormonal’’ and dioxin-like activities) of the
cells to the sample extracts were then evaluated, using a
variety of reporter assays, including androgenic, estrogenic,
dioxin-like, glucocorticoid-like, progesterone-like, peroxisome proliferator-like and retinoic acids related activities.
Cellular ATP/ROS Levels
ATP is a primary energy unit of cells for the maintenance of
most cellular activities, including DNA duplication, protein
synthesis, cell signaling and active transport. Thus, it is
important to evaluate sample extracts to see if they interfere
with cellular activities via modulation of ATP levels. In this
study none of the sample extracts caused significant effects on
cellular energy levels (Figures 2b and 3b). In addition to
effects on ATP levels, modulation of cellular ROS levels can
also adversely affect cell functions (Devasagayam et al.,
2004; Goetz and Luch, 2008). Although cells can normally
counterbalance ROS levels through the action of antioxidant
enzymes, excess ROS production may lead to cell injury, like
lipid peroxidation, DNA damage (Weitzman et al., 1994;
Franco et al., 2008) and apoptosis (Shen and Liu, 2006;
Azad et al., 2010). Sustained high levels of cellular ROS can
result in oxidative stress, gene mutation and may be
associated with aging, lessened male fertility (Makker et al.,
2009) and other oxidative stress related-diseases (Toyokuni
et al., 1995; Stadtman and Berlett, 1998; Migliore and
Coppede, 2002; Lin and Beal, 2006; Elahi et al., 2009). In
this study, formation of ROS was detected in cells exposed to
extracts from all the chicken skin samples, the chicken meat
sample from Brazil and the beef sample from China
(Figure 2c). The greatest formation of ROS was observed
in cells exposed to the extract of chicken skin from China.
The extracts from all fish samples had no noticeable effects
on cellular ROS levels (Figure 3c). Recent study has
demonstrated that greater consumption of animal meats
with skin was associated with twofold increases in risk of
prostate cancer recurrence of progression (Richman et al.,
2010). Therefore, in addition to the consideration of
saturated fat content in meat skin, the presence of
contaminants-related to oxidative stress might also impose
considerable human health risk.
Receptor-Mediated Reporter Assays
Dietary intake of exogenous substances with dioxin-like and
‘‘hormonal activity’’ are concerns for public health. It has
been reported that the consumption of EDC-contaminated
foods might induce early onset of puberty (Den Hond and
Schoeters, 2006; Roy et al., 2009) and reproductive disorders
(Paulozzi, 1999; Boisen et al., 2004; Tsutsumi, 2005; Crain
et al., 2008). Circulating concentrations of steroid hormones
such as estrogen, (E2), progesterone (P) and androgens have
been hypothesized to influence cancer risk, including breast,
ovarian, testicular and prostate cancers (Lukanova and
Kaaks, 2005; Folkerd and Dowsett, 2010). Chronic
97
Law et al.
Biological analysis of EDCs in food
exposure to the ligand of PPAR induces development of
cancers in livers of both rats and mice (Reddy et al., 1980,
1976; Rao and Reddy 1987; Pyper et al., 2010), whereas
elevated concentrations of glucocorticoids in blood might
lead to insulin resistance and diabetes (Chrousos and Kino,
2009; Longui and Faria, 2009; Barnes, 2010). EDCs with
retinoic acid-like activities can interfere with embryonic
development and differentiation of secondary characteristics
of males (Bowles et al., 2006; Bowles and Koopman, 2007).
Dioxins the most toxic anthropogenic pollutants are also
linked to disorders of developmental and reproduction
(Hotchkiss et al., 2008; Bruner-Tran and Osteen, 2010).
Therefore, there was a need to develop a rapid screening
panel of assays for a cost-effective routine measurement of
possible EDC contamination in different food products.
In the present study, the dioxin-responsive element (DRE)
and various steroid hormone responsive elements were cloned
into luciferase reporter vectors. The dioxin-like and the
hormonal modulating potentials in extracts of food were
measured by use of luciferase reporter constructs transfected
cells to form the bases of transactivation assays. Our data
indicated that extracts of foods exhibited both dioxin-like and
hormone-like or hormone-mimic potentials (Table 2). Fish
samples exhibited the greatest androgenic (ARE: 0.32–
6.6 nM/g dw), dioxin-like (DRE: 9.92–37.6 pM/g dw),
glucocorticoid-like (GRE: 0.015–6.642 nM/g dw), peroxisome proliferator-like (PPRE: 0.048–10.3 mM/g dw) and
retinoic acid-like (RARE: 0.06–0.146 nM/g dw) activities.
Extracts of chicken skin exhibited the greatest estrogenic
effects (ERE: 67–93 pM/g dw), followed by dioxin-like and
progesterone-like activities. Chicken meat extracts exhibited
glucocorticoid-like potency (GRE: 0.28–4.72 nM/g dw)
followed by dioxin-like, retinoic acid-like and peroxisome
proliferator-like potencies. Beef and pork extracts exhibited
lesser ‘‘hormonal’’ potencies. The extract of pork from Brazil
exhibited the greatest progesterone-like (PRE: 1.403 mM/g
dw) potencies. No androgenic and retinoic acid-like activities
were detected in pork or beef. Our results reveal that fish
products contribute the greatest proportion of exposure to
pollutants that are active through the screened mechanisms of
Table 2. The effects of various food extracts on the promoter-driven luciferase activities.
Samples
ARE
nM/g dw
DRE
pM/g dw
0
0
0
0
0.144±0.019c
1.212±0.127b
2.187±0.205b
1.944±0.254b
0.027±0.003c
0.461±0.051b
0.133±0.009b
0.04±0.002c
Beef
Brazil
China
HK
USA
Pork
Brazil
China
HK
Canada
Chicken (Skin)
Brazil
China
HK
USA
Chicken (muscle)
Brazil
China
HK
USA
ERE
pM/g dw
GRE
nM/g dw
PRE
mM/g dw
PPRE
mM/g dw
RARE
nM/ g dw
81±11.12a
93±9.48a
77±8.21a
67±5.49a
0.078±0.005c
0
0
0
0.82±0.096b
0.166±0.009c
0.64±0.078 b
0.989±0.113b
1.101±0.014b
0.186±0.023d
0.224±0.032d
0.06±0.007d
0.003±0.0004c
0
0.018±0.003b
0
1.854±0.239b
2.418±0.214b
1.488±0.118b
2.468±0.282b
3.923±0.475c
4.224±0.334c
5.612±0.289c
3.906±0.441c
0.2867±0.011b
4.72±0.523a
4.067±0.462a
0.804±0.059b
0.476±0.066c
0.001±0.002c
0.138±0.022c
0.152±0.028c
1.221±0.132b
1.355±0.114b
0.997±0.089b
1.674±0.178b
0.031±0.004b
0.042±0.003b
0.15±0.028a
0.01±0.002b
0
0
0
0
1.494±0.136b
2.801±0.347b
2.148±0.234b
2.908±0.381b
0.532±0.078d
0.759±0.065d
0.839±0.091d
3.855±0.433c
0
0.32±0.012b
0.042±0.006c
0
0.174±0.013c
0.179±0.021c
0.036±0.005c
0.006±0.001c
0.596±0.083c
1.032±0.098b
0.252±0.039d
0.36±0.031d
0
0
0
0
0
0
0
0
0.977±0.133b
0.152±0.025c
0.477±0.034c
1.042±0.127b
0.592±0.062d
1.109±0.187d
2.2±0.312c
2.647±0.338c
0
0
0
0
1.403±0.217a
0.278±0.031c
0.243±0.033c
0.341±0.042c
0.063±0.053d
0.644±0.077c
0.787±0.063c
1.124±0.178b
0
0
0
0
Freshwater fish
Grass Carp
Spotted Snakehead
6.040±0.97a
0.326±0.05b
9.925±1.59a
11.231±2.35a
16.17±2.01b
20.99±2.34b
0.742±0.067b
0.432±0.057b
0.00029
0.00001
0.048±0.006d
9.077±0.872a
0.063±0.007b
0.092±0.008a
Seawater fish
Orange-spotted grouper
Bigeye
Bartail Flathead
1.828±0.25b
6.622±0.58a
6.053±0.90a
10.522±1.76a
37.60±4.59a
22.481±1.51a
13.75±1.45b
23.71±2.87b
38.06±4.21b
0.015±0.002c
3.781±0.421a
6.642±0.711a
0.00012
n/a
0.00000
2.108±0.230b
10.308±1.76a
0.213±0.031d
0.146±0.017a
0.116±0.009a
0.086±0.005a
Data are shown in mean±SD. Means followed by the same letter are not significantly different according to the results of one-way ANOVA followed by
Duncan’s multiple range tests (po0.05).
98
Journal of Exposure Science and Environmental Epidemiology (2012) 22(1)
Biological analysis of EDCs in food
action. This is particularly true in oceanic cities with heavy
industrial activities, the released/disposed chemical pollutants
into water systems make fish a source of various environmental toxicants to humans.
In conclusion, we have demonstrated a cost-effective and
rapid approach for the screening of EDC-elicited nonreceptor and receptor mediated biological activities. These
effects can be categorized as non-specific and specific cellular
responses to EDCs in foods. Our data demonstrated that the
fishes and chicken skins were contaminated with the greatest
concentrations of ‘‘hormonal’’ and dioxin-like potencies.
Although the physiological consequences of human consumption of these food items were not assessed in this study,
chronic exposure to these contaminated foods may impose
greater risk of endocrine disruption and adverse health
effects. The risks and potential effects of EDCs to health of
coastal populations in the Pearl River Delta are of concern
and should be assessed in greater detail both with bioassays
and bio-analytical screening tools. Epidemiological studies of
cohorts for EDC-specific effects would also be in order.
Conflict of interest
The authors declare no conflict of interest.
Acknowledgements
This work was supported Collaborative Research Fund
(HKBU 1/CRF/08 to Prof C.K.C. Wong) University Grants
Committee. Prof. Giesy was supported by the Canada
Research Chair program, an at large Chair Professorship at
the Department of Biology and Chemistry and State Key
Laboratory in Marine Pollution, City University of Hong
Kong, The Einstein Professor Program of the Chinese
Academy of Sciences and the Visiting Professor Program of
King Saud University.
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