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Breast-Milk Mercury Concentrations and Amalgam Surface in Mothers from Brasília, Brazil

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Human milk is the best source of nourishment for the newborn because of its incomparable balanced nutrition and psychological benefits to the infant's development. Dental fillings containing metallic Hg are the primary source of inorganic Hg contamination of humans. We studied Hg concentrations in the breast milk of mothers during the first month (7-30 d) postnatal in relation to the number of amalgam surfaces. The concentration of total Hg was determined in 23 samples of human milk collected from lactating mothers with a varied number of amalgam dental restorations. The average number of amalgam surfaces was 6.87 (5.81, SD) with a range of 0 to 20. The mean concentration of total Hg in breast milk was 5.73 ng/g (range: 0-23.07). The Pearson correlation coefficient was significant (r = 0.6087, p = 0.0057) between breast-milk Hg and number of amalgam surfaces. In 56.5% of low-fish-eating mothers, the amount of Hg likely to be ingested by breast-fed infants is above the World Health Organization reference.
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Breast-Milk Mercury Concentrations
and Amalgam Surface in Mothers
from Brasília, Brazil
SÉRGIO L. DA COSTA,1OLAF MALM,2
AND JOSÉ G. DÓREA*,1
1Faculdade de Ciências da Saúde, Universidade de Brasília,
Brasília, Brazil; and 2Laboratório de Radioisótopos Eduardo
Penna Franca, Instituto de Biofísica Carlos Chagas Filho,
Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
Received November 22, 2004; Revised December 17, 2004,
Accepted December 21, 2004
ABSTRACT
Human milk is the best source of nourishment for the newborn because
of its incomparable balanced nutrition and psychological benefits to the
infant’s development. Dental fillings containing metallic Hg are the primary
source of inorganic Hg contamination of humans. We studied Hg concen-
trations in the breast milk of mothers during the first month (7–30 d) post-
natal in relation to the number of amalgam surfaces. The concentration of
total Hg was determined in 23 samples of human milk collected from lactat-
ing mothers with a varied number of amalgam dental restorations. The aver-
age number of amalgam surfaces was 6.87 (5.81, SD) with a range of 0 to 20.
The mean concentration of total Hg in breast milk was 5.73 ng/g (range:
0–23.07). The Pearson correlation coefficient was significant (r= 0.6087, p=
0.0057) between breast-milk Hg and number of amalgam surfaces. In 56.5%
of low-fish-eating mothers, the amount of Hg likely to be ingested by breast-
fed infants is above the World Health Organization reference.
Index Entries: Mercury; human milk; amalgam; dental filling.
INTRODUCTION
Breast milk is essential to newborn infants. In addition to its incom-
parable source of balanced nutrition, it is fundamental for the psychologi-
Biological Trace Element Research 145 Vol. 106, 2005
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All rights of any nature, whatsoever, reserved.
0163-4984/05/10602–0145 $30.00
*Author to whom all correspondence and reprint requests should be addressed.
cal development of infants and the well-being of mothers. Although the
mammary gland is capable of filtering untoward substances from mater-
nal metabolism and environmental contamination (1,2), some toxic metals
can reach the human milk (2). Because of the known risk of neurotoxic
effects of Hg, its environmental exposure is of public health concern (3).
Maternal acquisition of Hg depends on its chemical form. Diet is the main
source of organic Hg (monomethyl mercury [MMHg]) bioaccumulated in
fish and seafood (4), but the amalgam filling is the principal source of inor-
ganic Hg (In-Hg) (2).
Maternal-exposure sources influence breast-milk total Hg concentra-
tions (2). Although breast-milk Hg concentrations have been determined
in many countries, few studies addressed the impact of amalgam fillings.
These studies were conducted in industrialized countries like Sweden (5),
Canada (6), and Germany (7,8) with likely high levels of industrial emis-
sions (9). Because of its wide use in “silver” amalgam for the last 170 yr,
concerns about the liberation of Hg vapor are amply justified (10). Lindow
et al. (11) reported that fetal and hair Hg was significantly higher in babies
when mothers had amalgam restoration procedures performed before or
during pregnancy. Vimy et al. (6,12) suggested that placement and
removal of amalgam in lactating mothers could subject neonates to expo-
sure risks.
The objective of this study is to determine Hg concentrations in breast
milk and its association with maternal amalgam dental restoration in order
to assess the risk of Hg intake by breast-fed infants.
MATERIALS AND METHODS
The research protocol was approved by the Ethical Committee of
Studies on Humans of the University of Brasilia. Lactating mothers were
recruited in the Pediatric Clinic of the University Hospital. After explain-
ing the purpose of the study, a written consent was presented and signed
by the volunteering mother. Mothers were selected among those who were
in good health, reporting no illness or complaints at the time of the study.
Excluding factors were dental work done during pregnancy. One hundred
twenty-one mothers between the ages of 18 and 32 yr were initially con-
tacted within the first month postnatal. However, only 23 mothers gave
enough milk for Hg determination.
For each mother, a complete clinical examination of oral health and
amalgam restoration evaluation were made before milk collection. At the
time of the visit, a sample of approx 6 mL of breast milk was collected by
manual milk expression, and with the aid of a questionnaire we assessed
frequency of fish consumption. The milk was stored in nitric acid-cleaned
vessels, refrigerated, and taken to the laboratory for Hg determination.
Mercury determination in breast milk was done by cold-vapor atomic
absorption spectroscopy with a flow-injection mercury system (FIMS)
146 da Costa, Malm, and Dórea
Biological Trace Element Research Vol. 106, 2005
(Perkin-Elmer). Analytical work was done at the Laboratório de Radioisó-
topos Eduardo Penna Franca, Instituto de Biofísica Carlos Chagas Filho of
Universidade Federal do Rio de Janeiro. We followed the routine proce-
dures of the laboratory, after adaptation of the analytical protocol used for
Hg determination in biological samples. Briefly, samples were freeze-dried
before acid digestion in H2SO4: HNO3(1 : 1) solution. The detection limit
of the method was calculated at three times the SD of blanks (0.43 µg
Hg/L). The Hg intake of breast-fed babies was estimated based on the
expected weight of 4 kg for a 21-d-old infant (average postpartum days
and an expected breast-milk intake of 150 g milk/kg/body wt/d).
RESULTS AND DISCUSSION
The breast-milk total Hg concentrations and main characteristics of
the mothers are shown in Table 1. Because Brasília is an interland city
away from coastal areas, the habitual fish consumption is considered low.
Indeed, the average reported fish consumption was one meal a week, with
some mothers reporting rarely consuming fish or seafood. The average
number of days for the last fish meal before milk collection was 38.7 d. The
mean number of dental amalgam surfaces was 6.87 (5.81 SD). A compara-
tive summary of results showing total Hg in breast milk of studies inves-
tigating the impact of dental amalgam on breast-milk Hg is shown in Table
2. The median milk Hg concentration is in the upper limit of reported
mean values. In our study, the significant correlation between number of
amalgam surfaces and total Hg in breast milk (Fig. 1) is in agreement with
most studies. The exception were the studies of Klemann et al. (8) and
Grandjean et al. (13) that showed no significant correlation between amal-
gam surfaces and transitional-milk Hg. Based on World Health Organiza-
tion (WHO) (14) recommendations, 56.5% (13/23) of the samples were
above reference (0.5 µg/kg/body wt) values.
There are recognizable differences in the metabolism of organic
(MMHg) and inorganic Hg. The serum half-life of inorganic Hg seems
shorter than MMHg. Oskarsson et al. (5) indicated that the proportion of
inorganic Hg (51%) in milk is higher than in maternal blood (26%). Stud-
ies of experimental ingestion of amalgam or after dental removal showed
a median half-life of 37 or 46 d respectively (15,16). This is coincident with
a urinary-clearance half-life of 41 d in occupational exposure of dental per-
sonnel (17). Nevertheless, studies by Oskarsson et al. (5) showed that in
Swedish mothers, the amalgam filling was the main source of Hg in breast
milk. It appears that mammary glands exert an important barrier that
restricts the transfer of Hg (organic and inorganic). In studies summarized
by Dórea (2), the highest mean blood Hg concentrations showed the low-
est milk–blood ratios.
There are maternal constitutional factors that affect Hg secretion into
breast milk, such as maternal age (18) and lactation stage (19). Both inor-
Mercury in Breast Milk 147
Biological Trace Element Research Vol. 106, 2005
ganic and organic Hg are found to be associated with proteins in breast
milk. Inorganic Hg is mostly bound to caseins and, in low proportions, to
albumin (20). Differential protein binding might significantly alter total Hg
transfer from maternal serum to milk. Furthermore, total protein concen-
trations decrease during lactation, from colostrum to mature milk (21), and
protein-concentration differences between colostrum and mature milk
might affect total Hg in milk. Indeed, there is a decline in Hg concentra-
tions between colostrum and mature milk (2). It is reasoned that low milk-
Hg concentrations in late lactation is attributed to low protein
concentrations. The colostrum has significantly higher protein concentra-
tions and, likewise, consistently high milk-Hg concentrations (2). Vahter et
al. (22) demonstrated a decreased Hg concentration in blood (In-Hg) and
in urine (total Hg) during the course of lactation. Coincidentally, a signifi-
cant correlation between colostrum Hg and amalgam filling cease to exist
in late lactation (19).
148 da Costa, Malm, and Dórea
Biological Trace Element Research Vol. 106, 2005
Table 1
Characteristics of Mothers, Total Breast-Milk Hg Concentrations
(ng/g or ng/mL), and Estimated Total Hg Intake by Breast-fed Infants.
Abbreviation: NA=not applicable.
* Below detection limit
Mercury in Breast Milk 149
Table 2
Comparison of Total Hg Mean Concentrations (ng/g or ng/mL)
in Breast Milk of Mothers Exposed to Inorganic Hg from Dental Amalgam
Abbreviations: LD=limit of detection for cold-vapor atomic absorption methods, NG=Not
given; d=days.
* Statistically significant;
** High dietary intakes of whale meat.
#mm3.
Hg determined by cold-vapor atomic fluorescence.
Fig. 1. Correlation between number of amalgam surfaces and total Hg in
breast milk. Fig. Scatter plot of dental amalgam fillings and breast-milk Hg con-
centrations (r= 0.6087; p=0.0057).
Biological Trace Element Research Vol. 106, 2005
Amalgam placement and removal and Hg exposure during prenatal
and postnatal periods were studied earlier and thought to be detrimental
to breast-fed babies (5,6,11,12). Contrary to these opinions, others con-
cluded that dental amalgam in breast-feeding mothers posed no threat to
fetuses and infants. Drasch et al. (7) compared Hg in breast milk and in
cow’s-milk-based formulas and concluded that even for mothers with
large numbers of dental amalgam, these fillings should pose little danger
to breast-feeding infants. Indeed, during the first 2 mo, it is uncertain if
any correlation between milk Hg concentrations and maternal amalgam
filling exists (19). In addition, Jones (10) estimated that 490 amalgam sur-
faces in a person’s mouth would be necessary to give off enough Hg vapor
and ionic Hg to meet maximum exposure guidelines. Because the amount
of Hg released from a dental amalgam is minimal, Drexler and Schaller
(19) concluded that Hg exposure in breast-fed babies from maternal amal-
gam is of no significance to fetal and neonatal Hg blood. Stoz et al. (23) also
reported that newly made tooth fillings during pregnancy had no influ-
ence on Hg concentrations in newborns. It should be noted that studies
that measured Se and Hg in the same sample of breast milk showed an
excess of Se ranging from 12-fold to 49-fold (2). This constitutes a protec-
tive aspect peculiar of breast-feeding that cannot be provided by cow’s
milk or formulas.
Summing up, in this sample of low-fish-eating population, maternal
amalgam dental restoration is significantly correlated with breast-milk Hg
concentration. Furthermore, the amount of Hg likely to be ingested by breast-
fed infants is above reference values set by WHO (14) in 56.5% of cases.
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This study aims to evaluate the level of mercury in the breast milk of Moroccan mothers and its association with several maternal parameters and habits, and to estimate the daily intake of the newborns. Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the concentrations of mercury in 70 colostrum samples. Indeed, a structured questionnaire was administrated during milk collection to report data concerning the maternal socioeconomic and anthropometric parameters, as well as dietary habits and smoking habits in the family, etc. The median of mercury in breast milk was 3,56 μg/L (range 1.64-124 μg/L) and exceeded normal levels of 1.7 μg/l, suggested by the World health organization in 99% of milk samples. Significant associations were found between mercury levels and the occurrence of previous miscarriages, anemia before pregnancy and vitamin & mineral supplementation during pregnancy, as well the frequency of consumption of cereals and the use of lipstick. The estimated daily intake was higher than the tolerable daily intake of the World health organization and the European food safety authority in 30% of newborns. These results need to be confirmed by multicenter studies to investigate the levels of mercury in the breast milk of the Moroccan population.
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This review covers a wide body of literature to gain an understanding of the impacts of informal activities related to metal extraction (primary mining and recycling) on early life exposure to neurotoxicants and on neurodevelopment. In primary mining, gold extraction with Hg amalgamation is the main environmental cause of Hg pollution in most artisanal small-scale gold mining (ASGM) activities around the world. Nevertheless, in Sub-Saharan Africa (SSA), Pb disrupted from gold-related ores, mining, and artisanal cookware production are an important neurotoxicant that seriously contaminates the affected population, with devastating effects on children. In e-waste recycling settings, the range of neurotoxic substances that contaminate mothers and children is wider than in primary mining environments. Thus, Hg and Pb are major pre- and postnatal neurotoxicants affecting children in the informal metal extraction activities and SSA countries show the highest record of human contamination and of neurotoxic effects on children. There are additional sources of neurotoxic contamination from mining and metal processing activities (cyanide tailing in South America and SSA) and/or co-exposure to Hg-containing products such as cosmetics (soaps and Hg-based skin lightening creams in Africa) and pediatric Thimerosal-containing vaccines (TCVs, that breaks down to ethyl-mercury) in current use in middle and low income countries. However, the action of these neurotoxicants (per se or in combination) on children needs more attention and research. Studies show a negative association between biomarkers of all environmental metal(loid)s (As, Cd, Hg, Mn, and Pb) studied and neurodevelopment in young children. Sadly, in many unregulated activities, child labor is widely employed, thus presenting an additional occupational exposure. Children living in polluted environments related to metal processing are disproportionately exposed to a wide range of co-occurring neurotoxic substances. The review showed compelling evidence from highly representative parts of the world (Africa, Asia, and Latin America) that the studied neurotoxic substances negatively affected areas of the brain associated with language, memory and executive function, as well as psychosocial behavior. Protecting the environment and children from unregulated and highly polluting metal extraction and processing are inextricably intertwined and deserve urgent attention.
Article
Environmental (and occupational) exposure to neurotoxic substances is a worldwide problem that can affect children's neurodevelopment (ND). In Latin American and Caribbean (LAC) countries there are over 300 million children living under the threat of neurodevelopmental delays due to toxic environmental exposure. Large industrial centers, intense mining and agricultural activities, along with changing complex ecosystems constitute a mosaic that drives contamination of air, water and the food chain. Neurotoxic contaminants such as pesticides (organochlorines, organophosphates, carbamates, pyrethroids, neonicotinoids, and manganese fungicides), chemicals of industrial use (phthalates), and metals (Hg, Pb, Al, As, F, Cd, Mo, Mn) are at the center of environmental exposure studies. Exposure to neurotoxic substances singly or in combination with other compounds or socioeconomic stressors (maternal education, socio-economic and nutritional status) intertwined with occupational and para-occupational exposure can affect ND (motor, cognition, behavior) of children. Significant negative effects of pesticides and neurotoxic elements on ND were found in all studied countries, affecting especially the less-privileged children from laboring families. Studies showed that exposures to the neurotoxicants in human milk are secondary to their more lasting effects during prenatal exposure. This review integrates exposure (prenatal and breastfeeding), metabolism, and ND effects of neurotoxicants. It highlights the overwhelming evidence showing that current levels of exposures are hazardous and detrimental to children's ND in LAC countries. The evidence indicates that a reduction in neurotoxicant exposure is essential to protect children's ND. Therefore, it is urgent to adopt policies and actions that prevent and remediate region-specific children's ND issues.
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This systematic review summarizes the finding of 58 studies from 33 countries, which assessed mercury concentrations in breast milk and the factors related to the level of contamination. We performed a literature search in Pubmed, Science Direct, and Google Scholar databases for studies published between 1976 and 2017 that are monitoring and measuring mercury in human breast milk and investigating the associated factors. Then, we extracted more information about the aim of the study, the country, samples size, time of lactation, mercury concentration, and other data. Most of the studies used mature milk or colostrum for analysis and in about 60% of them, the concentrations exceed significantly the limit set by the World Health Organization (WHO) of 1.7 µg/l; In addition, many factors and parameters were related to the level of mercury contamination in breast milk. Periodic monitoring surveys are recommended in each country to evaluate the level of mercury in milk of lactating women and to estimate the level of exposure of newborns.
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Dental amalgam is the major source of inorganic mercury (Hg) exposure in the general population. The objective of the present study was to obtain data on changes in Hg levels in blood, plasma, and urine following removal of all amalgam fillings during one dental session in 12 healthy subjects. The mean number of amalgam surfaces was 18 (range, 13 to 34). Frequent blood sampling and 24-hour urine collections were performed up to 115 days after amalgam removal, and in eight subjects additional samples of plasma and urine were collected up to three years after amalgam removal. A transient increase of Hg concentrations in blood and plasma was observed within 48 hours after amalgam removal. In plasma, the peak concentrations significantly exceeded the pre-removal plasma Hg levels by, on average, 32% (1.3 nmol/L; range, 0.1 to 4.2). No increase in the urinary Hg excretion rate was apparent after amalgam removal. An exponential decline of Hg was seen in all media. Sixty days after the amalgam removal, the Hg levels in blood, plasma, and urine had declined to approximately 60% of the pre-removal levels. In seven subjects, who were followed for up to three years, the half-lives of Hg in plasma and urine were calculated. In plasma, a bi-exponential model was applied, and the half-life was estimated at median 88 days (range, 21 to 121). The kinetics of Hg in urine (nmol/24 hrs) fit a mono-exponential model with a median half-life of 46 days (range, 35 to 67). It is concluded that the process of removing amalgam fillings can have a considerable impact on Hg levels in biological fluids. After removal, there was a considerable decline in the Hg levels of blood, plasma, and urine, which slowly approached those of subjects without any history of amalgam fillings.
Article
Total mercury concentrations (mean ± standard deviation) in breast milk, blood, and hair samples collected 6 wk after delivery from 30 women who lived in the north of Sweden were 0.6 ± 0.4 ng/g (3.0 ± 2.0 nmol/kg), 2.3 ± 1.0 ng/g (11.5 ± 5.0 nmol/kg), and 0.28 ± 0.16 μg/g (1.40 ± 0.80 μmol/kg), respectively. In milk, an average of 51% of total mercury was in the form of inorganic mercury, whereas in blood an average of only 26% was present in the inorganic form. Total and inorganic mercury levels in blood (r = .55, p = .003; and r = .46, p = .016; respectively) and milk (r = .47, p = .01; and r = .45, p = .018; respectively) were correlated with the number of amalgam fillings. The concentrations of total mercury and organic mercury (calculated by subtraction of inorganic mercury from total mercury) in blood (r = .59, p = .0006; and r = .56, p = .001; respectively) and total mercury in hair (r = .52, p = .006) were correlated with the estimated recent exposure to methylmercury via intake of fish. There was no significant between the milk levels of mercury in any chemical form and the estimated methylmercury intake. A significant correlation was found between levels of total mercury in blood and in milk (r = .66, p = .0001), with milk levels being an average of 27% of the blood levels. There was an association between inorganic mercury in blood and milk (r = .96, p < .0001); the average level of inorganic mercury in milk was 55% of the level of inorganic mercury in blood. No significant correlations were found between the levels of any form of mercury in milk and the levels of organic mercury in blood. The results indicated that there was an efficient transfer of inorganic mercury from blood to milk and that, in this population, mercury from amalgam fillings was the main source of mercury in milk. Exposure of the infant to mercury from breast milk was calculated to range up to 0.3 μg/kg · d, of which approximately one-half was inorganic mercury. This exposure, however, corresponds to approximately one-half the tolerable daily intake for adults recommended by the World Health Organization. We concluded that efforts should be made to decrease mercury burden in fertile women.
Article
In humans, the continuous release of Hg vapor from dental amalgam tooth restorations is markedly increased for prolonged periods after chewing. The present study establishes a time-course distribution for amalgam Hg in body tissues of adult and fetal sheep. Under general anesthesia, five pregnant ewes had twelve occlusal amalgam fillings containing radioactive 203Hg placed in teeth at 112 days gestation. Blood, amniotic fluid, feces, and urine specimens were collected at 1- to 3-day intervals for 16 days. From days 16-140 after amalgam placement (16-41 days for fetal lambs), tissue specimens were analyzed for radioactivity, and total Hg concentrations were calculated. Results demonstrate that Hg from dental amalgam will appear in maternal and fetal blood and amniotic fluid within 2 days after placement of amalgam tooth restorations. Excretion of some of this Hg will also commence within 2 days. All tissues examined displayed Hg accumulation. Highest concentrations of Hg from amalgam in the adult occurred in kidney and liver, whereas in the fetus the highest amalgam Hg concentrations appeared in liver and pituitary gland. The placenta progressively concentrated Hg as gestation advanced to term, and milk concentration of amalgam Hg postpartum provides a potential source of Hg exposure to the newborn. It is concluded that accumulation of amalgam Hg progresses in maternal and fetal tissues to a steady state with advancing gestation and is maintained. Dental amalgam usage as a tooth restorative material in pregnant women and children should be reconsidered.
Article
Coal combustors remain the major uncontrolled anthropogenic source of mercury due to an incomplete understanding of its emission chemistry. Using a new approach, this has now been resolved for the first time. Unexpectedly, mercury is seen to have a propensity for heterogeneous chemistry, previously considered implausible. In systems containing sulfur, it can efficiently deposit as mercuric sulfate. If sulfur-free, mercuric oxide forms. These then are subject to attack by gaseous hydrogen chloride with conversion to gaseous mercuric dichloride. This is the elusive, elegant and dominant mechanism, long overlooked, that can efficiently convert atomic mercury to its controllable water-soluble dichloride.
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Mercury pollution, due to gold mining has spread through the Amazon ecosystem reaching the food chain and affecting the indigenous people of the region. We studied the mercury contamination of 47 mothers and infants and the role of breast feeding in indices of mercury body burden in both groups, by measuring hair and milk Hg levels. Total mercury concentration of breast milk ranged from 0.0 to 24.8 (5.85, 5.2 S.D.) ng/g. Calculated levels of mercury exposure of breast fed babies indicated that 53% were above tolerable daily intakes (0.5 μg/kg body weight) recommended for adults by WHO. Mercury concentration in maternal hair was higher than in hair from breast-fed babies. Correlation analysis showed that mercury hair concentration in infants was significantly affected by maternal mercury contamination during pregnancy, but not during the post-natal breast-feeding period. The mercury concentration in milk was not significantly correlated with maternal or infant’s hair Hg. A statistically significant correlation was found only between maternal and infant’s hair mercury concentration (r=0.675; P=0.0001).
Article
The objective of this study was to get an estimate of the overall halftime for clearance of urinary mercury after cessation of a mercury vapor exposure. Ten dentists and dental nurses were selected and their urinary mercury excretion rates prior and after a summer vacation were measured. Estimates of their basic mercury excretions, originating from the environmental background and their own amalgam restorations, were individually subtracted to get the contributions deriving from occupational work. If assuming a first order of kinetics for the clearance of urinary mercury a median value of 41 days was achieved for the halftime searched, a value somewhat lower than those previously published. An explanation might be that the tailing effect of the decay curve here was eliminated by the taking of the background excretions into account.
Article
Human amniotic fluid was gained from 95 pregnant women by amniocentesis (group 1) and from 20 women during delivery (group 2). The concentrations of inorganic mercury in amniotic fluid as assessed directly by cold-vapor atomic absorption spectrophotometry (CV-AAS) averaged 0.29 +/- 0.1 microgram/l in group 1 and 0.86 +/- 0.25 microgram/l in group 2. Surface areas of dental amalgam fillings were also estimated in these women and ranged between 0 and 930 mm2. There was no correlation between the surface area of maternal amalgam fillings and the concentrations of inorganic mercury in amniotic fluid (r = -0.122 and -0.069, respectively). Furthermore, no positive correlation existed between amalgam fillings and the concentration of total mercury in maternal blood (4.48 +/- 2.33 micrograms/l) and in neonatal blood (3.28 +/- 1.57 micrograms/l) as measured by CV-AAS in group 2 (r = -0.4 and -0.12, respectively). Concentrations of total mercury were also measured by CV-AAS in the breast milk of 86 women, five to ten days after delivery. These concentrations averaged 1.9 +/- 1.6 micrograms/l and were also not significantly correlated to the maternal amalgam surface areas (r = 0.188). In conclusion, maternal amalgam fillings are of no importance for the mercury load of the fetus and the neonate.
Article
In humans, the continuous release of Hg vapor from dental amalgam tooth restorations is markedly increased for prolonged periods after chewing. The present study establishes a time-course distribution for amalgam Hg in body tissues of adult and fetal sheep. Under general anesthesia, five pregnant ewes had twelve occlusal amalgam fillings containing radioactive 203Hg placed in teeth at 112 days gestation. Blood, amniotic fluid, feces, and urine specimens were collected at 1- to 3-day intervals for 16 days. From days 16-140 after amalgam placement (16-41 days for fetal lambs), tissue specimens were analyzed for radioactivity, and total Hg concentrations were calculated. Results demonstrate that Hg from dental amalgam will appear in maternal and fetal blood and amniotic fluid within 2 days after placement of amalgam tooth restorations. Excretion of some of this Hg will also commence within 2 days. All tissues examined displayed Hg accumulation. Highest concentrations of Hg from amalgam in the adult occurred in kidney and liver, whereas in the fetus the highest amalgam Hg concentrations appeared in liver and pituitary gland. The placenta progressively concentrated Hg as gestation advanced to term, and milk concentration of amalgam Hg postpartum provides a potential source of Hg exposure to the newborn. It is concluded that accumulation of amalgam Hg progresses in maternal and fetal tissues to a steady state with advancing gestation and is maintained. Dental amalgam usage as a tooth restorative material in pregnant women and children should be reconsidered.