Dental associations with blood mercury in pregnant women

Abstract

ObjectivesThere is curiosity concerning the source of mercury that is absorbed into the mother's blood and which may affect the developing fetus. This study therefore sets out to determine the extent to which dental amalgam (DA) may contribute to total blood mercury (TBHg) levels of pregnant women in the UK.MethodsWhole blood samples and information on diet and socio‐demographic factors were collected from pregnant women (n = 4484) enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC). The whole blood samples were assayed for total mercury levels using inductively coupled plasma dynamic reaction cell mass spectrometry (ICP‐DRC‐MS), and the women were retrospectively asked about features of their dental care during the pregnancy. Linear regression was used to estimate the relative contributions of DA to TBHg levels (log‐transformed) based on R 2 values, compared to the results from dietary and socio‐demographic variables.ResultsThe contribution to the variance of the mothers' TBHg levels by dental variables was 6.47%, a figure comparable to the 8.75% shown for seafood consumption in this population. Dietary and dental variables explained 20.16% of the variance, with socio‐demographic variables contributing only a further 3.40%. The number of amalgams in the mouth at the start of pregnancy accounted for most of the variance in dental variables.ConclusionsDental amalgam contributes a comparable amount of variance in TBHg to seafood consumption in this population. However, because the measures of DA exposure were imprecise, these findings are likely to be an underestimate. There is no evidence to date in the literature that fetal exposures to mercury from maternal DAs have adverse effects on the developing child, but long‐term studies are warranted.

Risk of subsequent attention‐deficit/hyperactivity disorder among children and adolescents with amalgam restorations: A nationwide longitudinal study

“…However, other studies have shown no significant association between blood mercury levels and ADHD incidence among children in Korea (GM=2.4 μg/L), Romania (GM=0.1 μg/L) and the United States (GM=0.4 μg/L) . Although the present study did not have access to individual data on the blood mercury levels of the study population, dental amalgam might be responsible for approximately 6.5% of the variance in blood mercury levels . Berglund estimated that nine or more amalgam restorations can produce an average daily dose of 1.7 μg of inhaled mercury vapour, and only approximately 0.01% of swallowed mercury vapour is absorbed through the gastrointestinal tract .…”

“…26,28,29 Although the present study did not have access to individual data on the blood mercury levels of the | 51 study population, dental amalgam might be responsible for approximately 6.5% of the variance in blood mercury levels. 30 Berglund estimated that nine or more amalgam restorations can produce an average daily dose of 1.7 lg of inhaled mercury vapour, and only approximately 0.01% of swallowed mercury vapour is absorbed through the gastrointestinal tract. 31 In our study, it was assumed that the total amount of mercury detected was insufficient to be associated with future ADHD, even in those with six or more amalgam restorations.…”

Prenatal mercury exposure and offspring behaviour in childhood and adolescence

“…(b) The analysis of the prenatal blood for mercury took place 19 years after it was collected. Although it is conceivable that this would have biased the results, the levels achieved and the relationships with dietary and other factors such as dental mercury are similar to those found by others (Golding et al, 2013, Golding et al, 2016b). (c) Although we have allowed for a variety of factors associated with mercury levels and/or behaviour, it is possible that there are other confounders that should have been taken into account.…”

“…We show elsewhere (Golding et al, 2016b) the way in which the mercury level varied with maternal age (the older the higher the blood Hg), parity (the more previous pregnancies the lower the Hg), maternal education (the more advanced the level the higher the Hg level), prenatal smoking (associated with lower blood mercury), prenatal alcohol (increasing levels of Hg with increasing alcohol intake), and housing tenure (those in owner occupied housing had the highest, and those in public housing had the lowest mean levels of Hg). All these associations were significant at P < 0.0001.…”

Maternal prenatal blood mercury is not adversely associated with offspring IQ at 8 years provided the mother eats fish: A British prebirth cohort study

“…We have shown elsewhere that there were no differences between the women for whom a trace metal result was obtained compared with the rest of the population in relation to their seafood intake or dental treatment ( Golding et al, 2013 , Golding et al, 2016 ). In Table 1 we also show that there was no bias in regard to a variety of social conditions and lifestyles, except that older and/or more educated women were more likely to have had blood taken for trace metal analyses.…”