Arch Environ Contam Toxicol (2009) 56:615–622 DOI 10.1007/s00244-008-9213-7
Prenatal and Early Childhood Exposure to Mercury and Methylmercury in Spain, a High-Fish-Consumer Country Sergi Dı´ez Æ Sandra Delgado Æ Inmaculada Aguilera Æ Jenaro Astray Æ Beatriz Pe´rez-Go´mez Æ Maties Torrent Æ Jordi Sunyer Æ Josep M. Bayona
Received: 29 May 2008 / Accepted: 21 July 2008 / Published online: 4 October 2008 Ó Springer Science+Business Media, LLC 2008
Abstract Exposure to mercury, a risk factor for neurodevelopmental toxicity, was assessed in Spanish children (preschool children and newborns, n = 218) in a fourlocations survey by performing mercury determination in hair. To assess the prenatal and children’s exposure and its potential risk, total mercury (THg) and methylmercury (MeHg) were analyzed and examined for associations with maternal sociodemographic characteristics and dietary intake through interviews and food frequency questionnaires. The mean THg in hair was 0.94 lg/g, ranging from
J. Astray and B. Pe´rez-Go´mez: On behalf of the Bio-Madrid Research Group. S. Dı´ez (&) S. Delgado J. M. Bayona Environmental Chemistry Department, IDÆA-CSIC, Jordi Girona, 18-26, 08034 Barcelona, Spain e-mail:
[email protected];
[email protected] S. Dı´ez Environmental Geology Department, ICTJA-CSIC, Lluı´s Sole´ i Sabarı´s, s/n, 08028 Barcelona, Spain I. Aguilera J. Sunyer Centre for Research in Environmental Epidemiology (CREAL), Municipal Institute of Medical Research (IMIM-Hospital del Mar), Barcelona, Spain J. Astray Institute of Public Health, Madrid Regional Health & Consumer Affairs Authority, Madrid, Spain B. Pe´rez-Go´mez Environmental and Cancer Epidemiology Unit, National Center for Epidemiology (ISCIII), Madrid, Spain M. Torrent IB-Salut, Menorca, Spain
0.19 to 5.63 lg/g in preschool children and 1.68 lg/g (0.13–8.43 lg/g) in newborns. Associations between mercury levels in hair and fish consumption frequency were found regardless of the group evaluated. Neither other food item nor maternal covariates were associated with mercury levels in the newborn group. In children, the mean THg values among frequent fish consumers (more than four times per week) were almost threefold higher compared with non-consumers (1.40 vs. 0.49 lg/g). Newborns from mothers who had intake of fish two or more times per week exhibited nearly threefold higher hair levels than those who rarely or never consumed fish (2.26 vs. 0.78 lg/g). Finally, mercury levels in hair exceeded the EPA reference dose (RfD) of 0.1 lg Hg/kg body weight per day (equivalent to 1 lg Hg/g hair) in 42% of the population studied. Overall, we conclude that levels of mercury in Spain are among the highest in the non-exposed populations probably because of the relatively high fish consumption.
Introduction Mercury is a potent toxic element that can cause severe neurological damage to humans. The target organ of the most toxic form, methylmercury (MeHg) is the brain, especially in the early stage of development, when the brain is highly vulnerable because of the ability of MeHg to easily cross the blood–brain and placental barriers (Dı´ez 2008). MeHg distributes all over body tissues and is accumulated into scalp hair. Since toxicological manifestations of mercury exposure have become known, many studies have been carried out for its determination in different human tissues (Canuel et al. 2006; Clarkson et al. 2007; Dı´ez et al. 2008; Johnsson et al. 2005).
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To determine the effect of MeHg on humans, it is preferred to use a biomarker that reflects the MeHg concentration in the brain (Cernichiari et al. 1995). Mercury concentrations in scalp hair and blood are used as biomarkers for MeHg in both the adult and fetal brain, although each provides a somewhat different reflection of exposure (NRC 2000). Blood gives an estimate of shortterm exposure (100–140 days), whereas hair reflects the average exposure over the growth period of the segment. In addition, which of these two constitutes the better indicator of fetal brain exposure remains a matter of current debate. The mercury concentration in hair reflects the MeHg concentration in the blood during hair formation and is frequently used as a biomarker for evaluating MeHg exposure. In fact, MeHg is incorporated into hair follicles in proportion to its content in blood. The hair-to-plasma ratio in humans is about 2500 to 1, whereas, the hair-to-whole blood ratio has been estimated to be about 250 to1 (IPCS 1990). Once incorporated into the hair, the mercury is stable and can provide a history of exposure (IPCS 1990; Phelps et al. 1980). Hair grows at an approximate rate of about 1 cm/month, and past exposure studies can be performed depending on the length of the hair analyzed. Because the half-life of MeHg in the body is about 1.5–2 months (Smith and Farris 1996), the hair closest to the scalp reflects current exposures and recent blood concentrations. Furthermore, MeHg levels in hair and THg are linearly correlated, with MeHg accounting for 70–80% of hair THg (Cernichiari et al. 1995; Dolbec et al. 2001). The advantages of Hg assessment in hair are that hair collection is non-invasive, and good response rates can be achieved in population subgroups that are difficult to obtain blood specimens from, such as children. The convenience of sampling and storage has made scalp hair advantageous for monitoring and field studies, and it has been extensively demonstrated that the THg concentration in hair reflects the average MeHg concentrations in circulating in blood. This study is a contribution to the INMA Network [INfancia y Medio Ambiente (Environment and Childhood)] (Fernandez et al. 2007; Ribas-Fito et al. 2006), a population-based cohort study in different Spanish cities that focuses on prenatal environmental exposures and growth, development, and health from early fetal life until childhood. The present study widens a previous one focused only in two cohorts (Montuori et al. 2006). Here, we report on a survey of MeHg and THg levels in a cross section of representative Spanish children (4 years old or preschool children) and newborn subpopulations living in different areas of Spain to estimate the current mercury exposure levels. The aim of this work is also to evaluate the role of fish consumption in this exposure.
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Materials and Methods Areas and Population Study The survey was conducted in four different areas of Spain: the cities of Madrid and Sabadell, the island of Menorca, and the Ribera d’Ebre. Madrid and Sabadell are cities (*3 million and 200,000 inhabitants, respectively) located in the center and northeast of the country, respectively. Menorca island (*80,000 inhabitants), located in the northwestern Mediterranean Sea, has a tourist-based economy with almost no chemical industry. The Ribera d’Ebre area in northeastern Spain includes the village of Flix (*5,000 inhabitants), which is located near a chloralkali plant, and the rest of the towns of the administrative health district (*12,000 inhabitants). A total of 218 hair samples were collected from children aged from 0 to 4 years (97 males and 121 females) and analyzed. The subjects were newborns from Madrid (MAD; n = 57) and Sabadell (SAB; n = 25) cities and preschool children from Menorca (MEC; n = 65) and Ribera d’Ebre area (REA; n = 71). All subjects and analyses were split in different groups (e.g., newborns and preschool children). Questionnaire Variables The study was approved by the Ethical Committee of the CREAL and by the Ethical Committees of the hospitals involved in this study. Pregnant women received written and oral information about the study. Participants were asked for their written informed consent twice: once for their participation in the prenatal visits and the other time for the inclusion of their child into the follow-up study. Each mother–infant pair was surveyed in person and the mothers were interviewed and asked to fill out a formal questionnaire including variables such as child’s age, gender, body weight, height, lactation, gestational age (weeks), and maternal characteristics such as maternal age, country of origin, educational level, or social class. The food frequency questionnaire (FFQ) of about 100 food items was administered twice, once in the first visit (10– 13 weeks) after recruitment and again during their third trimester (28–32 weeks) to assess usual dietary intake during pregnancy. Participants in our study were asked how often, on average, they had consumed each food item over the past 3–4 months. The FFQ was a modified version of the Harvard questionnaire that was previously validated and adapted for adult Spanish populations (Vioque and Gonzalez 1991; Willett et al. 1985). The FFQ had 9 possible responses, ranging from ‘‘never or less than once per month’’ to ‘‘six or more per day,’’ and included 11 questions about fish intake (mixed fried fish, lean fish, large oily fish, small oily fish, canned tuna fish, canned sardine or
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mackerel, dry or smoked fish, processed fish) and 3 items for shellfish and cephalopods. Thereafter, the participants were asked about a number of aspects related to fish consumption, including the number of fish meals consumed per week and the type of fish, reflecting their average intake during 6 months. No respondent reported fish consumption more than once per day. The study design and detailed methodology for the neonates from MAD have been described elsewhere (Aragone´s et al. 2008). The FFQ for the preschool children is similar to that described previously for neonates. They were also asked for the type of fish, portion size, and number of fish meals consumed per week in the last year, with the following choices: never, once per week, twice per week, three times per week, four times per week, five to six times per week, once per day or more. Similarly, no respondent reported fish consumption more than once per day. Sample Analysis In order to determine the exposure during the last 6 months, 5 cm of hair, corresponding to 5–6 months of growth (Cernichiari et al. 1995) were taken. Total Mercury Analysis The total mercury (THg) determination in human hair were carried out by the AMA 254 from Leco Corp. (Altec, Praha, Czech Republic) following the method previously described (Dı´ez et al. 2007). Briefly, hair strands (5–6 cm) were precisely weighed (5–20 mg) in a nickel boat that was placed into the instrument and analyzed based on sample catalytic combustion, preconcentration by gold amalgamation, thermal desorption, and atomic absorption spectrometry (AAS). The entire analytical procedure was validated by analyzing two human hair Certified Reference Material (CRM), the NIES CRM No. 13 and the IAEA-086, both obtained from the National Institute of Environmental Studies, Environmental Agency of Japan and the International Atomic Energy Agency (IAEA; Vienna, Austria), respectively. Analyses of both CRMs at the beginning and the end of each set of samples (typically 10) ensured that the instrument remained calibrated along the study. Precision for the CRM analyses, as measured by relative standard deviation (RSD), was close to 8%. The limit of detection (LD) was calculated to be 0.0027 lg/g mercury, based on three times the standard deviation (SD) of the blank and a sample hair mass of 10 mg, whereas the limit of quantitation (LQ) is 0.009 lg/g of mercury according to IUPAC recommendations (Currie 1999). A blank (i.e., an empty sample nickel boat) was analyzed periodically to verify that mercury was not being carried over between samples.
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Methylmercury Analysis The MeHg was measured using a validated method described elsewhere (Dı´ez and Bayona 2002; Dı´ez et al. 2008; Montuori et al. 2004). Briefly, the hair samples were digested in a hot (100°C) nitric acid solution (350 ll). A cooled aliquot (25 ll) was transferred to a glass vial with an acetate buffer solution and also 40 ll of dipentylmercury (14 ng/g) as an internal standard and 50 ll of phenylmercury (12 ng/g) as the ethylation quality control. Finally, after derivatization with 1% aqueous NaBEt4 (500 ll), extraction was 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). NIES CRM No. 13 was used to validate the method. The LD obtained (0.040 lg/g) was three times the SD of the blank. The LQ was 0.080 lg/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. Statistical Methods Mercury concentrations were tested for normality and found to be not normally distributed. Accordingly, the data were log-transformed and then we used the Spearman (rs) correlation tests to assess for associations between variables. The differences between the groups and the influence of several potential factors such as age, gender, lactation, gestational age (weeks), and maternal characteristics such as country of origin, educational level, or social class were tested for significance using the Mann–Whitney U nonparametric test. Statistical analyses were conducted with SPSS, version 15 for Windows (SPSS Inc., Chicago, IL). In most of the statistical analysis, children and newborns were tested separately. Multiple linear regression analysis to assess the relation between covariates and THg was employed. All means are arithmetic unless otherwise noted. Statistical significance was defined as p B 0.05.
Results Population Study The concentrations of THg and MeHg in hair of all the subjects (newborns and preschoolers) studied are given in Table 1. Of the participants, 45% were males and 55% females. The mean of THg hair concentrations of the preschoolers (mean = 4.4 years old) studied was 0.94 ± 0.91 lg/g, ranging from 0.19 to 5.63 lg/g. The mean of
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Table 1 Summary comparing THg and MeHg concentrations (lg/g) in hair of preschool children (4 years old) and newborns ([3 weeks old) according to the area of study Spain area
n
THga
Range
MeHga
Range
% above EPA RfD
Total
218
1.416 ± 1.387
0.126–8.426
0.973 ± 1.104
0.081–6.992
42
Preschool children Menorca (MEC)
65
0.706 ± 0.665
0.225–3.826
0.490 ± 0.638
0.110–3.644
14
Ribera d’Ebre (REA)
71
1.093 ± 1.016
0.189–5.627
0.914 ± 1.107
0.081–6.992
40
Madrid (MAD)
57
1.417 ± 0.901
0.126–5.095
n.a.
n.a.
39
Sabadell (SAB)
25
1.999 ± 1.925
0.132–8.426
n.a.
n.a.
60
Newborns
a
Mean ± SD; n.a.: not analyzed
THg hair concentrations of the newborns (1.68 ± 1.45 lg/ g) was higher than in children, ranging from 0.13 to 8.43 lg/g. Considering the ratio of MeHg to THg in hair, similar results were found by area: MEC (mean: 75 ± 15, ranging from 37% to 98%) and REA (mean: 76 ± 17, ranging from 35% to 98%), which agrees with other studies (Barbosa et al. 2001; Lee et al. 2000). Differences between the groups of children studied were further examined (Fig. 1). Statistically significant differences in THg and MeHg levels were found between REA and MEC. To evaluate the current mercury exposure levels in Spanish children and newborns, concentrations of hair Hg in our study were compared with those in recent studies (Table 2). Questionnaire Covariates In the preschool children group, females had higher THg (1.06 lg/g) and MeHg (0.85 lg/g) than males (0.73 lg/g and 0.54 lg/g) in hair, but these differences were not statistically significant. Similar findings have been reported in Albania (Babi et al. 2000) and Spain (Batista et al. 1996), where girls exhibited higher Hg levels in hair than boys. We found evidence of a significant correlation between age with THg among the whole group tested (rs = 0.198; p = 0.033), whereas no statistically significant correlation was observed between mercury levels and lactation (rs = 0.155; p = 0.221). In the newborn group, race/ethnicity, gender, gestational age, and specific maternal characteristics such as age, country of origin, educational level, or social class or parity were independently associated with mercury levels.
frequency. No other food group (chicken, vegetables, fruits, eggs, etc.) was associated with mercury levels (data not shown). The THg levels stratified in accordance with frequency of fish consumption are presented (Fig. 2A). Frequency of fish consumption was classified into four categories: category 1: never (6%); category 2: 1–2 times/ week (56%); category 3: 3–4 times/week (23%); category 4: [4 times/week (15%). As expected, there was a marked increase in hair THg with reported fish consumption. The mean THg level in hair was 0.93 lg/g for the whole group, 0.49 lg/g for those who never ate fish, and 1.40 lg/g for those who reported the highest consumption of fish ([4 times/week). Therefore, the mean mercury level in the group with the highest fish consumption is near threefold higher than those that rarely or never ate fish. Nevertheless, no significant differences in THg (p = 0.183) were found between both groups. Hence, there was statistically significant difference between categories 1 and 3 (p = 0.023) and categories 2 and 3 (0.73 vs. 1.24 lg/g; p = 0.011). Moreover, categories 2 and 4 (p = 0.2) and 3 and 4 (p = 0.627) are not significantly different from each other. There is a positive correlation between the consumption of fish and THg (rs = 0.246; p = 0.007) and MeHg (rs = 0.219; p = 0.012). Figure 2A clearly shows that THg in hair significantly increases as the number of fish meals rises. Multivariate regression analysis revealed a significant relationship between THg in hair and independent variables such as gender, area of residence, and fish consumption. Table 3 shows that gender, fish consumption, and area of residence are related to THg in a mutually adjusted regression model (i.e., independently of each other) both in newborns and in preschoolers.
Diet Newborn Group Preschool Children Group We also examined hair mercury levels by each food item in the FFQ and found associations with fish consumption
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Hair mercury levels of newborns were analyzed in the FFQ for associations with their mother food items during pregnancy such as vegetables, meat, chicken, shellfish, and
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619
Table 2 Comparison of THg concentrations (lg/g dry weight) in human hair collected at various worldwide locations Location Faroe Islands
Mean
Range
Remarks
References Grandjean et al. (1997)
4.27
2.6–7.7
Mother at parturition
1.12
0.69–1.88
Children, 12 months
2.99
1.7–6.1
Children, 7 years
Tarragona, Spain
0.77
0.18–2.44
School children
Batista et al. (1996)
Negro river basin, Brazil
12.65
0–44.53
Children \15 years
Barbosa et al. (2001) Myers et al. (2000a)
Seychelles Islands Diwalwal, Philippines
6.80
0.5–26.7
Maternal hair
6.5
0.9–25.8
Children, 5–6 years
2.65
0.03–34.71
Control
2.77
0.03–13.17
Downstream of gold mine
1.71
0.03–8.91
Gold mine, non-occupational
3.62
0.03–37.76
Gold mine, occupational Maternal (children \12 years)
Cordier et al. (2002)
Children in gold-mining area
Adimado and Baah (2002)
French Guiana Upper Maroni
12.7 (10.2)
Camopi
6.7 (6.5)
Awala
2.8 (1.4)
Ghana Anwiaso
1.61
0.15–5.86
Sahuma
0.62
0.32–2.19
Tanoso
4.27
0.06–28.3
Elubo
1.21
0.07–3.19
Drasch et al. (2001)
Madeira Island
4.09
0.38–25.95
Children 7 years
Murata et al. (2002)
Germany
0.23
0.06–1.7
Children 8–10 years
Pesch et al. (2002)
Japan
1.64
0.45–6.32
Children 7 years
Murata et al. (2004)
USA
0.22
0.18–0.25
Children 1–5 years
McDowell et al. (2004)
Children \10 years fish consumers in gold-mining area
Dorea et al. (2005)
Eastern Amazonia, Brazil Kayabi
16.55
Cururu
4.76
Kaburua
2.87
Spain
1.68
0.13–8.43
Newborns
This study
0.94
0.19–5.63
Preschool children
This study
fish consumption (i.e., large oily fish, lean fish, canned tuna, and fried fish). As shown in Fig. 2B, THg in neonate’s hair correlated significantly to maternal fish consumption (rs = 0.430; p = 0.001) but not to shellfish consumption frequency. Indeed, regarding the fish class, only large oily fish was significantly associated with THg levels (rs = 0.400; p = 0.001). THg levels in hair for newborns significantly increased parallel to fish meal increases. Mothers who reported fish consumption more than 3–4 times/week had newborns with mean hair levels nearly threefold higher than women who rarely or never consumed fish (0.78 ± 0.55 vs. 2.26 ± 1.58 lg/g). No other food group (i.e., chicken, vegetables, fruits, eggs, etc.) was associated with mercury levels (data not shown).
Discussion A review of the literature (Table 2) suggests that mean THg levels in REA and MEC are lower than those reported for populations with high fish consumption, such as the Seychelles Islands (Myers et al. 2000b), the Faroe Islands (Grandjean et al. 1997), the Amazon basin (Barbosa et al. 1998; Dorea et al. 2005), and Japan and Madeira Island (Murata et al. 2002, 2004). On the other hand, Spanish preschool children exhibited higher THg levels than the children from Germany (Pesch et al. 2002) and from the United States (McDowell et al. 2004). Spanish median Hg levels was nearly fivefold the median Hg found in American children 1–5 years of age by the National Health and Nutrition Examination Survey (NHANES).
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1.0
children
Table 3 Multiple linear regression analysis [unstandardized coefficients (B), standard errors (SE), and standardized coefficients (b)] for hair mercury in Spanish children in two regression models by age
newborns
log Hg (µg/g) µ
0.5
Model Newborns
0.0
SE
(Constant)a
-0.059
0.092
Gender, male
-0.017
0.091 -0.023
Fish consumption SAB
-0.5
Preschool children (Constant)b -1.0
-1.5
Gender, male THg MeHg
MEC
0.304* 0.003
0.091 0.091
0.423* 0.005
-0.258*
0.051
-0.089
0.059 -0.133
Fish Consumption, times per week REA
MAD
SAB
3–4
0.161*
[4
0.158** 0.082
0.175**
0.113** 0.061
0.171**
Groups
REA
Levels (log THg) in females, whose mothers eat fish less than three times per month during pregnancy from Madrid (MAD)
b
Levels (log THg) in females, eating fish less than three times per week from Menorca (MEC) * p \ 0.05; ** p \ 0.1
A study of neurodevelopment in infants suggested that maternal mercury exposure, and fish intake, had opposing effects on visually-mediated neurobehavioral tests (Oken et al. 2005). Sakamoto et al. (2004) have reported a significant positive correlation between MeHg and DHA (docosahexaenoic acid, a special omega-3 fatty acid needed by the membranes of nerve and brain cells) concentrations in fetal circulation. These last results confirm that both MeHg and DHA, which originated from fish consumption, transferred from maternal to fetal circulation and, therefore, a decrease in fish consumption might cause decreases in MeHg and DHA levels. Pregnant women, in particular, should not give up eating fish at the risk of losing such benefits. However, they would do well to consume smaller fish, which contain lower MeHg levels, thereby balancing the risks and benefits from fish consumption. The Food and Drug Administration (FDA) and the US Environmental Protection Agency (EPA) have 2.0
A
0.5
log TlHg (µg/g)
log TlHg (µg/g)
1.0
0.208*
a
In other studies, the THg concentrations in neonatal hair have shown strong correlations with those in the maternal red blood cells, cord red blood cells and maternal hair (Sakamoto et al. 2008). This indicates that neonatal hair can also be used as a good biomarker of fetal exposure to Hg. Some studies have reported that hair of mother–newborns pairs has related Hg concentrations (Lindow et al. 2003; Razagui and Haswell 2001), but others have reported higher levels in the hair of neonates (Fujita and Takabatake 1977; Mohan et al. 2005). The findings of our study support the use of FFQ during pregnancy as a valuable warning of prenatal exposure to Hg as maternal hair or cord blood (Ramon et al. 2008). Our findings corroborated several other studies in adults and children, which have consistently indicated that mercury levels in different tissues of human body (e.g., hair and blood) correlate well with fish and seafood consumption (Carrington and Bolger 2002; Dı´ez et al. 2008; Fok et al. 2007; Goldman and Shannon 2001; McDowell et al. 2004; Morrissette et al. 2004, Ramon et al. 2008). Indeed, the frequency of fish consumption during pregnancy was the best predictor of the mercury concentration in neonates. Fig. 2 Correlation between mercury concentration in hair of children (A) and neonates (B) in relation to total consumption of fish (times/week)
0.073
Area of residence
Fig. 1 Mercury concentrations (THg and MeHg) in hair in relation to different Spanish groups. Boxes depict 25th, 50th, and 75th percentiles, and whiskers depict minimum and maximum values, excluding outliers (s)
0.0
B
1.0
0.0
-1.0
-0.5
-1.0
-2.0 never
1-2
3-4
>4
Fish Consumption (times/week)
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b
B
never
1-3 times/month 1 times/week 2-4 times/week
Fish Consumption
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made recommendations for selecting and eating fish or shellfish, such that women and young children will benefit from reduced exposure to mercury (Evans 2002; USEPA 2005). The FDA and EPA recommend eating no more than two servings (e.g., 12 oz. or 340 g) per week of fish and shellfish that are lower in mercury. If no advice is available, they recommend consuming no more than two fish meals per week. Spain is a country with a relatively high consumption of fish and is the second largest consumer of fish in the world after Japan. In a European cohort study, the highest consumption of fish products was noted in Spain (60 g/day, 2.5 meals/week) and the lowest in Germany (15 g/day) (Welch et al. 2002). In our newborn cohort, the mother’s mean fish intake during pregnancy was one to three times a month, which is much lower than the average in Spain and agrees with food safety authorities’ recommendations. In 2001, the EPA adopted a revised reference dose (RfD) for MeHg of 0.1 lg mercury/kg body weight per day. The RfD is based on neurologic developmental effects measured in children associated with exposure in utero to MeHg from the maternal diet and is related to a hair mercury concentration of 1.0 lg/g (USEPA 2005). In our study, more than half the subjects (58%) were below this reference concentration (Table 1). The percentages of the samples with mercury concentrations ranging from 1 to 2 lg/g and exceeding 2 lg/g were 28% and 14%, respectively. As noted previously, the mercury hair levels vary significantly with geographic region. Results are particularly interesting since they have been adjusted for frequency of fish consumption. This means that there are differences in mercury exposure for the different geographic regions after adjusting for the amount of fish consumed. The most obvious trend noticeable from our results is that hair mercury levels are significantly lower overall for individuals in MEC. This trend might be due to any combination of factors in the study population from MEC vs. REA. On the other hand, one of the most interesting findings of this work is that it seems that a significant maternal transfer of THg to newborn occurs. Exposure to neonates was evaluated by maternal FFQ because a significant correlation was obtained between mercury levels in neonates and maternal dietary fish intake parameters. Dietary questionnaires as a measure of exposure to mercury have been reported and validated in different populations (Legrand et al. 2005; MacIntosh et al. 1997; Tran et al. 2004). This is the first study investigating THg and MeHg levels in neonates and preschool children living in Spain. Overall, we conclude that levels of mercury in Spain are among the highest in the nonexposed populations probably because of the high fish consumption (almost 40% eat fish more than two times per week).
621 Acknowledgments Funding was obtained from the Ministry of Health (Instituto de Salud Carlos III) through the INMA Spanish network (Red INMA G03/176) and FIS-PI041436. We thank all the mothers, babies, and children who participated in the study for their generous collaboration. We also thank the gynecologists and birth attendants who collaborated in the sample collection. Sergi Dı´ez acknowledges the Spanish Ministry of Education and Science for his Ramo´n y Cajal contract. Technical assistance in the GC-CVAFS setup given by Ms. Rosa Mas is kindly acknowledged. The members of the Bio-Madrid Research Group are N. Aragone´s, B. Pe´rez-Go´mez, M. Polla´n, G. Lo´pez-Abente (CNE-ISCIII; CIBERESP); M. Martı´nez, J. Astray, A. M. Pe´rez-Meixeira, E. Gil, C. de Paz, A. Iriso, M. Cisneros, A. de Santos, J. F. Garcı´a, J. C. Sanz, A. Asensio, J. M. Garcı´a-Sagredo, A. de Leo´n A (Consejeria de Sanidad, Madrid), M. Ferna´ndez, M. J. Gonza´lez (CSIC).
References Adimado AA, Baah DA (2002) Mercury in human blood, urine, hair, nail, and fish from the Ankobra and Tano river basins in Southwestern Ghana. Bull Environ Contam Toxicol 68: 339–346 Aragone´s N, Pe´rez- Go´mez B, Astray J et al (2008) Biomonitoring of exposure to environmental pollutants in newborns and their parents in Madrid, Spain (BioMadrid): study design and field work. Gac Sanit (accepted) Babi D, Vasjari M, Celo V, Koroveshi M (2000) Some results on Hg content in hair in different populations in Albania. Sci Total Environ 259:55–60 Barbosa AC, Silva SRL, Dorea JG (1998) Concentration of mercury in hair of indigenous mothers and infants from the Amazon basin. Arch Environ Contam Toxicol 34:100–105 Barbosa AC, Jardim W, Dorea JG, Fosberg B, Souza J (2001) Hair mercury speciation as a function of gender, age, and body mass index in inhabitants of the Negro river basin, Amazon, Brazil. Arch Environ Contam Toxicol 40:439–444 Batista J, Schuhmacher M, Domingo JL, Corbella J (1996) Mercury in hair for a child population from Tarragona Province, Spain. Sci Total Environ 193:143–148 Canuel R, de Grosbois SB, Atikesse L et al (2006) New evidence on variations of human body burden of methylmercury from fish consumption. Environ Health Perspect 114:302–306 Carrington CD, Bolger MP (2002) An exposure assessment for methylmercury from seafood for consumers in the United States. Risk Anal 2:689–699 Cernichiari E, Brewer R, Myers GJ et al (1995) Monitoring methylmercury during pregnancy: maternal hair predicts fetal brain exposure. Neurotoxicol 16:705–709 Clarkson TW, Vyas JB, Ballatorl N (2007) Mechanisms of mercury disposition in the body. Am J Ind Med 50:757–764 Cordier S, Garel M, Mandereau L et al (2002) Neurodevelopmental investigations among methylmercury-exposed children in French Guiana. Environ Res 89:1–11 Currie LA (1999) Nomenclature in evaluation of analytical methods including detection and quantification capabilities (IUPAC Recommendations 1995). Anal Chim Acta 391:105–126 Dı´ez S, Bayona JM (2002) Determination of methylmercury in human hair by ethylation followed by headspace solid-phase microextraction-gas chromatography-cold-vapour atomic fluorescence spectrometry. J Chromatogr A 963:345–351 Dı´ez S, Montuori P, Querol X, Bayona JM (2007) Total mercury in the hair of children by combustion atomic absorption spectrometry (Comb-AAS). J Anal Toxicol 31:144–149
123
622 Dı´ez S, Montuori P, Pagano A et al (2008) Hair mercury levels in an urban population from southern Italy: fish consumption as a determinant of exposure. Environ Int 4:162–167 Dı´ez S (2008) Human health effects of methylmercury exposure. Rev Environ Contam Toxicol 198, in press. doi:10.1007/978-0-38709646-9 Dolbec J, Mergler D, Larribe F et al (2001) Sequential analysis of hair mercury levels in relation to fish diet of an Amazonian population, Brazil. Sci Total Environ 271:87–97 Dorea JG, Barbosa AC, Ferrari I, de Souza JR (2005) Fish consumption (hair mercury) and nutritional status of Amazonian Amer-Indian Children. Am J Hum Biol 17:507–514 Drasch G, Bose-O’Reilly S, Beinhoff C, Roider G, Maydl S (2001) The Mt. Diwata study on the Philippines 1999: assessing mercury intoxication of the population by small scale gold mining. Sci Total Environ 267:151–168 Evans EC (2002) The FDA recommendations on fish intake during pregnancy. J Obstet Gynecol Neonatal Nurs 31:715–720 Fernandez MF, Sunyer J, Grimalt J et al (2007) The Spanish Environment and Childhood Research Network (INMA study). Int J Hyg Environ Health 210:491–493 Fok TF, Lam HS, Ng PC et al (2007) Fetal methylmercury exposure as measured by cord blood mercury concentrations in a motherinfant cohort in Hong Kong. Environ Int 33:84–92 Fujita M, Takabatake E (1977) Mercury levels in human maternal and neonatal blood, hair and milk. Bull Environ Contam Toxicol 18:205–209 Goldman LR, Shannon MW (2001) Mercury in the environment: implications for pediatricians. Pediatrics 108:197–205 Grandjean P, Weihe P, White RF et al (1997) Cognitive deficit in 7year-old children with prenatal exposure to methylmercury. Neurotoxicol Teratol 19:417–428 IPCS (1990) Environmental Health Criteria 101. Methylmercury. World Health Organization, Geneva. Available from http://www.inchem.org/documents/ehc/ehc/ehc101.htm Johnsson C, Schutz A, Sallsten G (2005) Impact of consumption of freshwater fish on mercury levels in hair, blood, urine, and alveolar air. J Toxicol Environ Health A 68:129–140 Lee WC, Lee MJ, Lee SM et al (2000) An observation on the mercury contents of scalp hair in the urban residents of South Korea. Environ Toxicol Pharmacol 8:275–278 Legrand M, Arp P, Ritchie C, Chana HM (2005) Mercury exposure in two coastal communities of the Bay of Fundy, Canada. Environ Res 98:14–21 Lindow SW, Knight R, Batty J, Haswell SJ (2003) Maternal and neonatal hair mercury concentrations: the effect of dental amalgam. BJOG 110:287–291 MacIntosh DL, Williams PL, Hunter DJ et al (1997) Evaluation of a food frequency questionnaire food composition approach for estimating dietary intake of inorganic arsenic and methylmercury. Cancer Epidem Biomar 6:1043–1050 McDowell MA, Dillon CF, Osterloh J et al (2004) Hair mercury levels in US children and women of childbearing age: reference range data from NHANES 1999–2000. Environ Health Perspect 112:1165–1171 Mohan S, Tiller M, van der Voet G, Kanhai H (2005) Mercury exposure of mothers and newborns in Surinam: a pilot study. Clin Toxicol 43:101–104 Montuori P, Jover E, Alzaga R, Dı´ez S, Bayona JM (2004) Improvements in the methylmercury extraction from human hair by headspace solid-phase microextraction followed by gaschromatography cold-vapour atomic fluorescence spectrometry. J Chromatogr A 1025:71–75 Montuori P, Jover E, Dı´ez S et al (2006) Mercury speciation in the hair of pre-school children living near a chlor-alkali plant. Sci Total Environ 369:51–58
123
Arch Environ Contam Toxicol (2009) 56:615–622 Morrissette J, Takser L, St-Amour G et al (2004) Temporal variation of blood and hair mercury levels in pregnancy in relation to fish consumption history in a population living along the St. Lawrence River. Environ Res 95:363–374 Murata K, Budtz-Jorgensen E, Grandjean P (2002) Benchmark dose calculations for methylmercury-associated delays on evoked potential latencies in two cohorts of children. Risk Anal 22:465–474 Murata K, Sakamoto M, Nakai K et al (2004) Effects of methylmercury on neurodevelopment in Japanese children in relation to the Madeiran study. Int Arch Occup Environ Health 77:571–579 Myers GJ, Davidson PW, Cox C et al (2000a) Twenty-seven years studying the human neurotoxicity of methylmercury exposure. Environ Res 83:275–285 Myers GJ, Davidson PW, Palumbo D et al (2000b) Secondary analysis from the Seychelles child development study: the child behavior checklist. Environ Res 84:12–19 NRC (2000) Toxicological effects of methylmercury. National Research Council. National Academy Press, Washington, DC Oken E, Wright RO, Kleinman KP et al (2005) Maternal fish consumption, hair mercury, and infant cognition in a US cohort. Environ Health Perspect 113:1376–1380 Pesch A, Wilhelm M, Rostek U et al (2002) Mercury concentrations in urine, scalp hair, and saliva in children from Germany. J Expo Anal Environ Epidemiol 12:252–258 Phelps RW, Clarkson TW, Kershaw TG, Wheatley B (1980) Interrelationships of blood and hair mercury concentrations in a North-American population exposed to methylmercury. Arch Environ Health 35:161–168 Ramon R, Murcia M, Ballester F et al (2008) Prenatal exposure to mercury in a prospective mother-infant cohort study in a Mediterranean area, Valencia, Spain. Sci Total Environ 392: 69–78 Razagui IBA, Haswell SJ (2001) Mercury and selenium concentrations in maternal and neonatal scalp hair: relationship to amalgam-based dental treatment received during pregnancy. Biol Trace Elem Res 81:1–19 Ribas-Fito N, Ramon R, Ballester F et al (2006) Child health and the environment: the INMA spanish study. Paediat Perinatal Epidemiol 20:403–410 Sakamoto M, Kubota M, Liu XH et al (2004) Maternal and fetal mercury and n–3 polyunsaturated fatty acids as a risk and benefit of fish consumption to fetus. Environ Sci Technol 38:3860–3863 Sakamoto M, Kubota M, Murata K et al (2008) Changes in mercury concentrations of segmental maternal hair during gestation and their correlations with other biomarkers of fetal exposure to methylmercury in the Japanese population. Environ Res 106:270–276 Smith JC, Farris FF (1996) Methyl mercury pharmacokinetics in man: a reevaluation. Toxicol Appl Pharmacol 137:245–252 Tran NL, Barraj L, Smith K, Javier A, Burke TA (2004) Combining food frequency and survey data to quantify long-term dietary exposure: a methyl mercury case study. Risk Anal 24:19–30 USEPA (2005) (US Environmental Protection Agency, Office of Science and Technology, Office of Water). Water quality criterion for the protection of human health. methylmercury 2005. Available from http://www.epa.gov/waterscience/criteria/ methylmercury/document.html. Accessed April 2008 Vioque J, Gonzalez L (1991) Validity of a food frequency questionnaire (preliminary results). Eur J Cancer Prev 1:19–20 Welch AA, Lund E, Amiano P et al (2002) Variability of fish consumption within the 10 European countries participating in the European Investigation into Cancer and Nutrition (EPIC) study. Public Health Nutr 5:1273–1285 Willett WC, Sampson L, Stampfer MJ et al (1985) Reproducibility and validity of a semiquantitative food frequency questionnaire. Am J Epidemiol 122:51–65
