Science of the Total Environment 369 (2006) 51 – 58
www.elsevier.com/locate/scitotenv
Mercury speciation in the hair of pre-school children living
near a chlor-alkali plant
Paolo Montuori a , Eric Jover b , Sergi Díez b,⁎, Núria Ribas-Fitó c , Jordi Sunyer c ,
Maria Triassi a , Josep M. Bayona b
a
Department of Preventive Medical Sciences, University of Naples “Federico II”, C/ Sergio Pansini, 5, Naples, E-80131, Italy
b
Environmental Chemistry Department, I.I.Q.A.B.-C.S.I.C., C/ Jordi Girona, 18–26, Barcelona, E-08034, Spain
c
Respiratory and Environmental Health Research Unit, Institut Municipal d'Investigació Mèdica,
C/ Doctor Aiguader, 80, Barcelona E-08003, Spain
Received 8 July 2005; received in revised form 6 April 2006; accepted 14 April 2006
Available online 12 June 2006
Abstract
Exposure to mercury species was assessed in the hair of 130 Spanish children (age 4) from the general population in two areas.
Both areas are exposed to different sources of mercury: a point source in Ribera d'Ebre (northeastern Spain) and a diffuse source on
the island of Menorca (northwestern Mediterranean). The median MeHg values in the hair of children from Ribera d'Ebre (RE)
were nearly twice (0.631 μg/g vs. 0.370 μg/g) those of children from Menorca (MC) (p b 0.05). Total Hg showed a similar trend
(REmedian: 0.720 μg/g vs. MCmedian: 0.476 μg/g). Nevertheless, inorganic mercury levels were similar in the two groups of children
(REmedian: 0.186 μg/g vs. MCmedian: 0.210 μg/g). Two subgroups of the Ribera d'Ebre group were defined: children living in Flix (a
village near a chlor-alkali plant) (RE1) and children living on the outskirts of Flix with no clear, direct influence of the plant (RE2).
The mercury concentrations in RE1 were also significantly higher than those in Menorca, but no significant differences were found
between Menorca and the RE2 subgroup. We evaluated the fish consumption of RE1, RE2 and MC and found that the Menorcan
children consumed significantly less fish (p b 0.05) than the other two subgroups. Children who consumed fish more than three
times a week had higher MeHg concentrations (β (SE) = 0.991 (0.279) than those who ate it less than once a week. Nevertheless,
the differences in MeHg levels between children from Ribera d'Ebre and Menorca remained statistically significant after
adjustment for fish intake and other variables (β (SE) = 0.779 (0.203) for children from RE1). In conclusion, local sources other
than seafood contribute significantly to MeHg content in hair in the two Ribera d'Ebre subgroups.
© 2006 Elsevier B.V. All rights reserved.
Keywords: Mercury exposure; Mercury speciation; Methylmercury; Children's hair; Routes of mercury intake; Sex effect
1. Introduction
Mercury is a naturally occurring element that is widespread in the environment (Schuster et al., 2002; Gustin,
⁎ Corresponding author. Tel.: +34 93 400 61 00; fax: +34 93 204 59
04.
E-mail address: [email protected] (S. Díez).
0048-9697/$ - see front matter © 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.scitotenv.2006.04.003
2003; Mather and Pyle, 2004). Human activity has
increased its release, mobilization and distribution into the
environment (Yokoyama et al., 2000; Heebink and
Hassett, 2002). Once released into the environment,
inorganic mercury (I-Hg) undergoes biotic and abiotic
transformations to become methylmercury (MeHg), a
more toxic organic form (Wood et al., 1968; Greenwood,
1985; Palheta and Taylor, 1995; Kinjo et al., 1996). MeHg
52
P. Montuori et al. / Science of the Total Environment 369 (2006) 51–58
can accumulate in animal tissues and cause biomagnifications in the aquatic food chain. Its concentrations are the
highest in top predatory species (de Souza Lima et al.,
2000). Therefore, fish-consuming populations are a highrisk group for MeHg exposure (Choi, 1989; IPCS, 1990).
MeHg is primarily neurotoxic (Castoldi et al., 2001; Costa
et al., 2004) and affects neurodevelopment, especially
during early development, the most susceptible period
(NRC, 2000).
Humans are exposed to MeHg primarily through seafood consumption (Clarkson and Strain, 2003; Daniels et
al., 2004). Some studies have demonstrated the neurological injuries caused by low-level MeHg exposure
(Mendola et al., 2002; Grandjean et al., 2004). Recent
prospective epidemiological studies in the Faroe Islands,
the Seychelles Islands and New Zealand have assessed the
developmental effects of lower-level MeHg exposure in
fish-consuming populations caused by maternal and fetal
exposure to MeHg (Cernichiari et al., 1995; Grandjean et
al., 1997; Crump et al., 1998).
Mercury biomarker studies have analyzed different
human body fluids and tissues such as blood, urine, nails
and hair (Adimado and Baah, 2002; Mortada et al., 2002;
Mahaffey et al., 2004). Hair is a suitable medium for
monitoring human exposure to mercury, because it reflects organ mercury levels and dietary intake (McDowell
et al., 2004; Yasutake et al., 2004). Several studies have
reported a strong correlation between MeHg content in
hair and MeHg content in blood. The hair-to-blood ratio in
humans has been estimated at approximately 250:1
(IPCS, 1990; Gill et al., 2002). Furthermore, MeHg levels
in hair and total Hg are linearly related (Pellizzari et al.,
1999), with MeHg accounting for 70–80% of total Hg
(Cernichiari et al., 1995).
This study aims to assess mercury exposure through
mercury speciation in the hair of 130 Spanish children
(age 4). In order to evaluate the risks associated with a
chlor-alkali plant and determine the role of fish consumption on mercury concentrations, we determined
methylmercury (MeHg) and total mercury (T-Hg) levels
in three subgroups living in different areas of northeastern Spain, one of which is near the plant.
2. Materials and methods
2.1. Areas of study
The survey was conducted in two different areas of
Spain: the island of Menorca and Ribera d'Ebre. Menorca,
located in the northwestern Mediterranean Sea, has a
tourist economy with little industry. The Ribera d'Ebre
area in northeastern Spain includes the village of Flix (ca.
5000 inhabitants), which is located near an electrochemical factory, and the rest of the towns of the administrative
health district (ca. 12,000 inhabitants). The factory, built
in 1898, has been producing chlorinated solvents for
decades. Hg electrodes are used to produce chlorine gas
(Cl2) and caustic soda. Unusually high atmospheric concentrations of hexachlorobenzene (HCB) have been found
in Flix (Sala et al., 1999). The OSPAR Commission has
reported mercury emissions in the area (OSPAR, 2004).
2.2. Population of study
The Ribera d'Ebre group (hereafter denoted RE)
included children from the village of Flix (RE1) and its
outskirts (RE2) born in the area's main hospital between
March 1997 and December 1999 for whom data on
pregnancy, delivery, lactation and environment are available. A total of 102 of the 113 eligible children (90%)
were enrolled and 71 provided complete exposure and
outcome data up to the fourth-year visit (68.6%).
The Menorca group (hereafter denoted MC) included
children born between January 1997 and March 1998. A
total of 482 of the 513 eligible children (94%) were
enrolled and 470 (97.5%) provided complete outcome
data up to the fourth-year visit. Of these children, 59
(12.5%) were selected randomly to have the mercury in
their hair measured. There were no differences between
the children selected for mercury measurements and those
who were not. RE was exposed to a large chlor-alkali plant
located in Flix and MC was an external group with no
point sources of mercury contamination, which was managed as a control group. We also considered that similar
geographical populations may not necessarily have the
same distribution of MeHg in hair because of different
environmental conditions. Based on this assumption, RE
was divided into two subgroups: the inhabitants of the
village itself (n = 38), denoted RE1, and the children from
five other villages (n = 33), denoted RE2.
The mothers of the selected children were contacted
and the objectives and methods to be used were described to them. All of the mothers of the selected children agreed to participate and gave their consent. The
study was approved by the ethics committee of the
Institut Municipal d'Investigació Mèdica (IMIM,
Spain). The selected children were all 4 years old and
appeared healthy. None of them reported specific
exposure to mercury or had major congenital anomalies
or other diseases. The gender, weight and personal information of each subject were recorded. Each mother–
infant pair was surveyed in person and the mothers were
interviewed and asked to fill out a formal questionnaire
about possible sources of mercury exposure such as
P. Montuori et al. / Science of the Total Environment 369 (2006) 51–58
foods and beverages. The type and the quantity of foods
and beverages ingested were recorded. The participants
were asked about a range of aspects related to fish consumption, including the number of fish meals consumed
per week, the type of fish and portion size. They were
also asked how often they consumed different fish species in the last year, with the following choices: never,
once per week, twice per week, 3 times per week, 4 times
per week, 5–6 times per week, once per day or more. A
lock of scalp hair approximately 5 cm long was obtained,
usually from the nape. The samples were coded and
stored in sealed plastic bags until analysis. Table 1 summarizes the results of the food-frequency questionnaires.
The hair samples were analyzed for both MeHg and total
mercury (T-Hg).
The RE subgroups were tested separately. Hence, the
RE1 subgroup (children from the village near the electrochemical factory) and the RE2 subgroup (children
from five villages surrounding Flix) were defined to test
the differences in MeHg and T-Hg.
2.3. Statistical methods
The differences between the groups were tested for
significance using nonparametric tests (Mann–Whitney
U). Multiple linear regressions were used to test how
variables other than location determined MeHg concentrations. The statistical regression models were performed
with Statgraphics (version 4.0, Statistical Graphic
53
Corporation, Englewood Cliffs, NJ, USA). Simple
regression was used to test different model types (linear,
multiplicative, exponential, logarithmic, reciprocal, etc.)
that contain just one independent variable. The software
program fitted several curvilinear models to the data and
listed the models in decreasing order of R-squared. Of the
models fitted, the best was the one with the highest Rsquared value. All other statistical analyses were conducted with SPSS, version 12.01 for Windows (SPSS
Inc., Chicago, IL). All means are arithmetic unless otherwise noted. Statistical significance was defined as
p ≤ 0.05. Cases with values above or below 1.5 times
the interquartile range were not considered for the statistical analysis, as defined by the Tukey method.
2.4. Analytical procedures
MeHg was measured using the method described
above (Montuori et al., 2004). The hair samples were cut
finely and placed in a 100-mL beaker that had been
ultrasonically washed with a nonionic surfactant. Then,
they were rinsed thoroughly and allowed to air dry.
Subsamples (20 mg) were then digested in a hot (100 °C)
nitric acid solution (350 μL). After the digest had cooled
to room temperature, an aliquot was transferred to a glass
vial with an acetate buffer solution. Dipentylmercury and
phenylmercury were added as internal standard and
ethylation quality control respectively. Finally, after derivatization with aqueous NaBEt4, extraction was
Table 1
Description of variables of interest by area
Menorca (MC) (n = 59)
Ribera d'Ebre (RE) (n = 71)
Flix (RE1) (n = 38)
Outskirts Flix (RE2) (n = 33)
Mother
Maternal age, years (mean)
BMI, kg/m2 (mean)
29
22.8
30
23.6
31
24.0
Child
Gender (%)
Females
Males
Gestational age, weeks (median)
Birthweight, g (mean)
MeHg (mean ± SD) (μg/g) (median)
I-Hg (mean ± SD) (μg/g) (median)
Food consumption (%)⁎
Fish
Shellfish
Poultry
Pork
Eggs
48.9
51.1
40
3186
0.470 ± 0.628 (0.370)
0.211 ± 0.072 (0.210)
None
1–2
6.8
64.4
37.3
55.9
1.7
59.3
10.2
67.8
1.7
61.0
48.1
51.9
40
3221
1.104 ± 1.245 (0.821)
0.183 ± 0.069 (0.165)
None
1–2
5.3
47.4
50.0
39.5
2.6
57.9
2.6
73.7
5.3
63.2
33.3
66.7
40
3277
0.701 ± 0.900 (0.406)
0.212 ± 0.097 (0.204)
None
1–2
3.0
45.5
42.4
51.5
6.1
60.6
6.1
72.7
3.0
60.6
N2
28.8
6.8
39.0
22.0
37.3
⁎Normalized weekly intake frequency at the age of 4 years according to the different food categories.
N2
47.4
10.5
39.5
23.7
31.5
N2
51.5
6.1
33.3
21.2
36.4
54
P. Montuori et al. / Science of the Total Environment 369 (2006) 51–58
accomplished using solid-phase microextraction
(SPME). The final detection was carried out using a
gas chromatograph equipped with a cold-vapor atomic
fluorescence spectrometry system (GC-CVAFS). A
certified human-hair reference material from the National
Institute of Environmental Studies of Japan (NIES, CRM
No. 13) was used to validate the method. The limit of
detection (LOD) obtained (0.040 μg/g) was three times
the SD of the blank. The limit of quantification was
0.080 μg/g, the lowest point on the calibration plot.
Digestion recoveries were calculated using a reference
material analysis, obtaining yields of 75 ± 11%. Each
sample was analyzed in triplicate.
T-Hg was measured using the method described by
Chen et al. (2002), with minor modifications. Hair
samples were quantified by external calibration with
R2 N 0.99. The LOD obtained was 0.090 μg/g and the
limit of quantification of the method was estimated at
0.160 μg/g. The accuracy of this method was calculated
by reference material analysis (GBW 09101, Shanghai
Institute of Nuclear Research), which obtained 88% ±
6% (n = 7) with respect to the certified value. Each
sample was analyzed in triplicate. I-Hg, defined in
several studies (Chen et al., 2002) as [I-Hg] = [T-Hg] −
[MeHg], was calculated in order to determine which
type of mercury (organic or inorganic) was the most
sensitive to the differences observed between the target
groups. About 2–3% of the total number of samples
analyzed were below the LOD.
3. Results
Table 1 describes the characteristics of the population
by study area. Children from MC were more likely to
consume fish less than twice per week. Their mothers
were more likely to have a lower body mass index (BMI)
and be younger and more educated than the mothers from
Ribera d'Ebre. Within the Ribera d'Ebre cohort, children
from RE2 were more likely to be males and their mothers
were more likely to be less educated.
The mean of MeHg hair concentrations of all of the
children studied was 0.723 ± 0.943 μg/g, ranging from
0.081 to 6.992 μg/g. The maximum concentrations
were found in the children living in RE. The median
value of MeHg concentrations in hair of RE was nearly
twice that of MC (0.631 μg/g vs. 0.370 μg/g). The
median value of MeHg concentrations of RE1 was
more than twice that of MC and RE2. The same trends
were observed for T-Hg, with a RE median of 0.720 μg/
g (1.012 μg/g in RE1 and 0.610 μg/g in RE2) and a MC
median of 0.476 μg/g. For I-Hg, similar concentrations
were obtained for the different population groups, as
shown in Table 1.
Multivariate analyses with the outlier and extreme
data did not alter the results appreciably. The means and
medians increased slightly when outlier and extreme
data were included. Three outliers with mercury values
above or below 1.5 times the interquartile range were
removed from further analysis.
Table 2
Summary comparing children (b15 years old) total mercury concentrations and range in hair according with the area of study
Country
Year
Spain
Total
Menorca (MC)
Ribera d'Ebre
Flix (RE1)
Outskirts Flix (RE2)
Japan
USA
Madeira Island
Germany
Brazil, Amazon
Negro river basin
Kayabi
Cururu
Kaburua
Seychelles Islands
Faroe Islands
2002
a
b
2002–2003
1999–2000
1998
1996
1998
2002–2003
86
77
1989–1990
1986–1987
Mean ± SD.
95% CI (confidence interval).
n
Study group
Hair T-Hg (μg/g) a
130
59
71
38
33
327
838
113
245
4 years
7 years
1–5 years
7 years
8–10 years
0.938 ± 0.908 (0.189–5.627)
0.720 ± 0.664 (0.225–3.826)
1.093 ± 1.016 (0.189–5.627)
1.259 ± 1.079 (0.189–5.627)
0.922 ± 0.948 (0.195–4.960)
1.64 (0.45–6.32)
0.22 (0.18–0.25) b
4.09 (0.38–25.95)
0.23 ± 0.20 (b 0.06–1.7)
708
b15 years
b10 years
b10 years
b10 years
5–6 years
12.65 ± 8.66 (0–44.53)
16.55 ± 11.44
4.76 ± 2.09
2.87 ± 2.13
6.5 ± 3.3 (0.9–25.8)
527
903
Child, 12 months
Child, 7 years
1.12 (0.69–1.88)
2.99 (1.7–6.1)
Reference
This study
73
40
Murata et al. (2004)
McDowell et al. (2004)
Murata et al. (2002)
Pesch et al. (2002)
Barbosa et al. (2001)
Dorea et al. (2005)
Dorea et al. (2005)
Dorea et al. (2005)
Myers et al. (2000)
Grandjean et al. (1997)
P. Montuori et al. / Science of the Total Environment 369 (2006) 51–58
Table 3
Association (β (SE)) between fish consumption, residence and gender
and hair mercury concentrations in Menorca (MC), Flix (RE1) and
Outskirts Flix (RE2)
Control group
(MC)
a
T-Hg
MeHg
I-Hg
0.623
0.494
0.188
Fish consumption, times per week
1–2
0.165 (0.219) 0.103 (0.229)
2–3
0.260 (0.245) 0.221 (0.251)
N3
1.050 (0.260) b 0.991 (0.279) b
Residence
RE1
RE2
Gender, male
0.031 (0.056)
− 0.011 (0.065)
− 0.023 (0.070)
0.509 (0.198) b 0.779 (0.203) b − 0.103 (0.051) b
− 0.084 (0.206) 0.033 (0.221)
0.030 (0.054)
− 0.285 (0.175) − 0.424 (0.173) b 0.036 (0.045)
a
Each column is a different multivariate model. Values were
adjusted for maternal social class and birth-weight.
b
p-value b 0.05.
However, in order to evaluate mercury levels (T-Hg)
in Spanish children, these values were compared with
those from other studies (Table 2).
Table 3 shows the results of the final linear regression
model for mercury concentrations. The beta coefficients
(β) are the coefficients from the multivariate regression
analysis and the regression coefficient is the change in
response per unit of change in the predictor. The standard
errors (SE) are the standard errors of the regression
coefficients.
Finally, considering the ratio of MeHg to total Hg in
hair, similar results were found in MC (mean 75 ± 15,
ranging from 37% to 98%) and RE (mean 76 ± 17, ranging
from 35% to 98%). In all samples, the same trends were
found when a reciprocal-x model of regression analysis
was performed to determine the percentage of organic
fraction of Hg (MeHg) in hair as a function of T-Hg
content. The equation of the fitted model is
% MeHg = 97.2947 − 17,299.5 / [T-Hg]. Since the Pvalue in the analysis of variance is less than 0.05, there
is a statistically significant relationship between MeHg
and T-Hg at the 95% confidence level. The R-squared
statistics indicate that the model as fitted explains 70.83%
of the variability in MeHg. The correlation coefficient of
− 0.8416 indicates a moderately strong relationship
between the variables.
4. Discussion
We examined recent epidemiological studies of mercury exposure in children (Counter and Buchanan, 2004).
Table 2 shows several T-Hg concentrations reported for
other groups and/or cohorts of children worldwide. It is
55
difficult to compare the data in this study with studies
from other countries, because most of them are carried out
with children of different ages (usually N 10 years old).
Table 2 shows that the mean T-Hg levels in RE and
MC are lower than those reported for populations exposed to MeHg through high-frequency fish consumption, such as the populations in the two most outstanding
epidemiological studies of the past decade, carried out in
the Seychelles Islands (Myers et al., 2000) and the Faroe
Islands (Grandjean et al., 1997). The levels are also
lower than those reported in the Amazon basin (Barbosa
et al., 2001; Dorea et al., 2005), Japan and Madeira
Island (Murata et al., 2002, 2004). In fact, the children in
our study could be better compared to children in
Germany (Pesch et al., 2002) and the US (McDowell et
al., 2004). Spanish mercury levels are much higher that
those in either study. In our research, the median Hg
level among participants was over 5 times the median
Hg level found in American children 1–5 years of age
by the National Health and Nutrition Examination
Survey (NHANES) (n = 838). In addition, the mean THg level was approximately 1/3 of the average T-Hg
levels found in the Faroe Islands study. The USEPA's
MeHg reference dose (RfD) is based on these results.
The USEPA defines an RfD of 0.1 μg mercury/kg of
body weight per day, which corresponds to a level of
1.0 μg/g hair (USEPA, 2005). Approximately 31% of
the RE children (44.7% RE1 and 15.2% RE2) and about
6.8% of the MC children had mercury levels in their hair
that exceeded this RfD, which shows the relevance of
this contaminant.
We examined further interesting differences between
the groups of children studied. Significant differences in
T-Hg were found between RE and MC and between
RE1 and MC (p b 0.05). Surprisingly, the two RE subgroups were significantly different from each other and
RE2 was not different from MC (p = 0.267). Similar
speciation results were obtained for MeHg. However, no
significant differences in I-Hg (p N 0.05) were found in
the different groups of children.
These results indicate that children living in RE had
higher concentrations of MeHg in their scalp hair than
those in MC. Fish consumption (β (SE) = 0.991 (0.279))
and sex (β (SE) = − 0.424 (0.173)) were also associated
with MeHg concentrations. This statement is in
agreement with authors who have reported a significant
association between the presence of MeHg in hair and
being female. Some authors have reported that the
children's sex was the variable that most influenced Hg
content in hair (Batista et al., 1996), with significantly
higher Hg levels in girls than in boys. Similar findings
were previously reported by several authors (Lie et al.,
56
P. Montuori et al. / Science of the Total Environment 369 (2006) 51–58
1982; Watanabe et al., 1994), but Nakagawa (1995)
found higher Hg concentrations in males than in females
for a Japanese group.
However, the differences in MeHg content between
the children from RE and MC remain statistically significant after adjustment for fish intake and sex (β (SE) =
0.779 (0.203) for children from RE1). However, there is
no association between the I-Hg levels in hair and the
frequency of fish consumption. No other variables, such
as maternal body mass index, age, education, social
class, birth weight or gestational age, were associated
with individual MeHg levels. In addition, previous
studies have shown that the meat of animals fed with
fish meal or other fish products is likely to contribute to
MeHg exposure (Ask Björnberg et al., 2003; Lindberg
et al., 2004). Nevertheless, since no significant correlation was found between MeHg exposure and pork,
poultry and egg intake, these possible sources of toxic
MeHg exposure were discarded in our survey (Table 3).
The reference value (0.494 for mercury) refers to
females from MC who consumed fish less than once a
week. A boy from RE1 who consumed fish more than 3
times per week would have a mercury concentration of
1.84: 0.494 (reference) + 0.991 (estimate for fish consumption N 3 per week) + 0.779 (estimate for residence
in Flix) − 0.424 (estimate for male). A girl with the same
residence and fish consumption would have a mercury
concentration of 2.264. In summary, although fish consumption is the most important variable influencing Hg
content in hair, the place of residence has an effect.
The two RE subgroups had significant differences in
MeHg content. Since these two subgroups had similar
food-consumption habits, the higher MeHg content in
the hair of children from Flix may be attributed to the
industrial activity that has caused Hg emissions near
Flix for over a century. Furthermore, no significant MeHg
differences were found between MC and RE2. Therefore,
the RE2 group is more similar to MC than to RE1, despite
the geographic and food-consumption differences.
Nevertheless, Horvat et al. (2003) performed a study
in a major Hg-production area and concluded that the
local population may be exposed via consumption of
Hg-contaminated food and inhalation. Other studies
have shown higher exposure to mercury for people
working in or living near mercury-related industries
(Aks et al., 1995).
Finally, the MeHg percentages with respect to T-Hg
concentrations in hair found in our study are in accordance with other studies (Lee et al., 2000; Barbosa et al.,
2001). In fact, we found a significant correlation between MeHg and T-Hg levels in the scalp hair of children. The organic mercury fraction in hair increased
significantly as T-Hg increased (Fig. 1). Therefore,
increased T-Hg in hair reflects exposure to organic Hg,
which accumulates more easily in the organism. These
results are in agreement with other studies of the relationship between T-Hg and MeHg in blood and
emphasize the strong correlation between Hg content
in hair and blood (Mahaffey et al., 2004). Presumably,
this could be because inorganic Hg has a faster excretion
time than MeHg because it is more liposoluble. In fact,
Clarkson (1993) and WHO (IPCS, 1990) reported that
MeHg has a half-life in the body of about 50 days, with a
range of 20–70 days, and a half-life in the hair of about
65 days, with a range of about 35–100 days, indicating
that MeHg leaves the body slowly. I-Hg remains
100
% MeHg
80
Comparison of Alternative Models
60
Model
Reciprocal-X
Logarithmic-X
S-curve
Square root-X
Multiplicative
Linear
Square root-Y
Double reciprocal
Exponential
Reciprocal-Y
40
20
Correlation
R-Squared
-0,8416
0,8151
-0,7916
0,7575
0,7339
0,6804
0,6405
0,6210
0,5836
-0,4119
70,83%
66,45%
62,66%
57,39%
53,86%
46,30%
41,03%
38,56%
34,06%
16,97%
0
0
1
2
3
4
5
6
T-Hg (µg/g)
Fig. 1. Reciprocal-x model of MeHg proportion in T-Hg hair concentrations for total children. % MeHg = 97.2947 − 17,299.5 / [T-Hg]; Rsquared = 70.83%.
P. Montuori et al. / Science of the Total Environment 369 (2006) 51–58
roughly constant in the organism and MeHg is the main
form and can accumulate.
In summary, we determined the MeHg levels in
children's scalp hair in two geographical areas of Spain.
We believe that the different MeHg concentrations in the
three groups of children are related to fish consumption,
area of residence and gender. Our general conclusion is
that people living close to the chlor-alkali plant (RE1:
Flix subgroup) have higher levels of MeHg than people
living within 15 km (RE2: Flix outskirts subgroup).
Even though we found that the intake of Hg through
food consumption (fish in particular) was possibly the
most important parameter for all of the groups studied,
the living environment could not be disregarded. Populations with similar fish consumption may receive
different levels of exposure to mercury due to their
proximity to mercury-related industrial activities.
Acknowledgements
Funding was obtained from the Ministry of Health
through the INMA Spanish network. S. D. acknowledges Spanish Ministry of Education and Science for his
“Ramón y Cajal” Contract. Technical assistance in the
GC-CV AFS setup given by Ms. Rosa Mas is kindly
acknowledged.
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