A comparison of individual-level vs. hypothetically pooled mercury biomonitoring data from the Maternal Organics Monitoring Study (MOMS), Alaska, 1999-2012

Metal exposure in the Greenlandic ACCEPT cohort: follow-up and comparison with other Arctic populations

Humans are exposed to metals through diet and lifestyle e.g. smoking. Some metals are essential for physiologically body functions, while others are non-essential and can be toxic to humans. This study follows up on metal concentrations in the Greenlandic ACCEPT birth-cohort (mothers and fathers) and compares with other Arctic populations. The data from 2019 to 2020 include blood metal concentrations, lifestyle and food frequency questionnaires from 101 mothers and 76 fathers, 24-55 years, living in Nuuk, Sisimiut, and Ilulissat. A high percentage (25-45%) exceeded international guidance values for Hg. For the mothers, the metal concentrations changed significantly from inclusion at pregnancy to this follow-up 3-5 years after birth; some increased and others decreased. Most metals differed significantly between mothers and fathers, while few also differed between residential towns. Several metals correlated significantly with marine food intake and socio-economic factors, but the direction of the correlations varied. Traditional marine food intake was associated positively with Se, As and Hg. To the best of our knowledge, this study provides the most recent data on metal exposure of both men and women in Greenland, elucidating metal exposure sources among Arctic populations, and documents the need for continuing biomonitoring to follow the exceeding of guidance values for Hg. [Figure: see text].

Exposure to organophosphate esters among Inuit adults of Nunavik, Canada

Halogenated organophosphate esters (OPEs) are increasingly used as flame retardants to replace polybrominated diphenyl ethers (PBDEs), which have been phased out due to their confirmed persistence, toxicity, and ability to undergo long range atmospheric transport. Non-halogenated OPEs are primarily used as plasticizers. While human exposure to PBDEs in the Canadian Arctic is well documented, it is not the case for OPEs. To assess the exposure to OPEs in Inuit living in Nunavik (northern Québec, Canada), we measured 16 metabolites of halogenated and non-halogenated OPEs in pooled urine samples from the last population health survey conducted in Nunavik, the Qanuilirpitaa? 2017 Inuit Health Survey (Q2017). Urine samples (n = 1266) were pooled into 30 pools by sex (female; male), age groups (16-19; 20-29; 30-39; 40-59; 60+ years old) and regions (Hudson Bay; Hudson Strait; Ungava Bay). Q2017 geometric means and 95 % confidence intervals were compared with data from the Canadian Health Measures Survey Cycle 6 (2018-2019) (CHMS). Halogenated OPEs were systematically detected and generally found at higher concentrations than non-halogenated OPEs in both Q2017 and CHMS. Furthermore, urinary levels of BCIPP and BDCIPP (halogenated) were lower in Q2017 compared to CHMS while concentrations of DPhP, DpCP and DoCP (non-halogenated) were similar between Q2017 and CHMS. Across the 16 metabolites measured in Q2017, BCIPHIPP (halogenated) had the highest levels (geometric mean: 1.40 μg/g creatinine). This metabolite was not measured in CHMS and should be included in future surveys. Overall, our results show that Inuit in Nunavik are exposed to lower or similar OPEs levels than the rest of the general Canadian population suggesting that the main current exposure to OPEs may be from consumer goods containing flame retardants and imported from the south rather than long-range atmospheric transport to the Arctic.

Environmental contaminants in Arctic human populations: Trends over 30 years

INTRODUCTION

Arctic Monitoring and Assessment Programme (AMAP) monitors persistent organic pollutant (POP) levels in the Arctic populations and assesses health effects related to exposure to them. Many internationally regulated POPs persist in humans and biota, while new Emerging Contaminants of Arctic Concern (ECAC), many of which are unregulated, present additional challenges. Biomonitoring offers valuable insights into temporal trends within human matrices, revealing critical information not only about the efficacy of international regulations but also serving as an early warning system for exposure and risks for human health.

METHODS

Data analyzed in this study is aggregated data presented in the AMAP Human Health in the Arctic assessments, which provide data on contaminant concentrations measured in human matrices from adults, and children across various population studies conducted in the Arctic since the 1980 s. Linear regression analyses were used to assess trends of various POPs including organochlorine (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and per- and polyfluoroalkyl substances (PFAS), measured over time from the Arctic populations in Finland, Norway, Sweden, Denmark, Iceland, Canada and Alaska (USA).

RESULTS

Overall, decreasing trends were observed for PCBs and OCPs. Regulated PFAS showed decreasing trends, but increasing trends were observed for unregulated PFAS in certain populations. PBDEs showed decreasing or inconsistent trends in certain Arctic populations.

CONCLUSIONS

Decreasing trends are observed for legacy POPs, but the trends for new emerging contaminants are inconsistent. More focus is needed on biomonitoring the new emerging contaminants of concern in the Arctic and their implications on human health.

Impact of a Prenatal Vitamin D Supplementation Program on Vitamin D Deficiency, Rickets and Early Childhood Caries in an Alaska Native Population

Background: Early childhood rickets increased in Alaska Native children after decreases in vitamin D-rich subsistence diet in childbearing-aged women. We evaluated the impact of routine prenatal vitamin D supplementation initiated in Alaska’s Yukon Kuskokwim Delta in Fall 2016. Methods: We queried electronic health records of prenatal women with 25(OH) vitamin D testing during the period 2015−2019. We evaluated 25(OH)D concentrations, vitamin D3 supplement refills, and decayed, missing, and filled teeth (dmft) scores and rickets in offspring. Results: Mean 25(OH)D concentrations increased 36.5% from pre- to post-supplementation; the percentage with deficient 25(OH)D decreased by 66.4%. Women with ≥ 60 vitamin D3 refill days had higher late pregnancy 25(OH)D concentrations than those with no refill days (p < 0.0001). Women with late pregnancy insufficient 25(OH)D concentrations had offspring with higher dmft scores than those with sufficient 25(OH)D (RR 1.3, p < 0.0001). Three children were diagnosed with nutritional rickets during the period 2001−2021, and none after 2017. Conclusions: These findings suggest that prenatal vitamin D supplementation can improve childhood outcomes in high-risk populations with high rates of rickets.

MercuNorth - monitoring mercury in pregnant women from the Arctic as a baseline to assess the effectiveness of the Minamata Convention

Exposure to mercury (Hg) is a global concern, particularly among Arctic populations that rely on the consumption of marine mammals and fish which are the main route of Hg exposure for Arctic populations.The MercuNorth project was created to establish baseline Hg levels across several Arctic regions during the period preceding the Minamata Convention. Blood samples were collected from 669 pregnant women, aged 18-44 years, between 2010 and 2016 from sites across the circumpolar Arctic including Alaska (USA), Nunavik (Canada), Greenland, Iceland, Norway, Sweden, Northern Lapland (Finland) and Murmansk Oblast (Russia). Descriptive statistics were calculated, multiple pairwise comparisons were made between regions, and unadjusted linear trend analyses were performed.Geometric mean concentrations of total Hg were highest in Nunavik (5.20 µg/L)  and Greenland (3.79 µg/L), followed by Alaska (2.13 µg/L), with much lower concentrations observed in the other regions (ranged between 0.48 and 1.29 µg/L). In Nunavik, Alaska and Greenland, blood Hg concentrations have decreased significantly since 1992, 2000 and 2010 respectively with % annual decreases of 4.7%, 7.5% and 2.7%, respectively.These circumpolar data combined with fish and marine mammal consumption data can be used for assessing long-term Hg trends and the effectiveness of the Minamata Convention.

Local polynomial regression for pooled response data

We propose local polynomial estimators for the conditional mean of a continuous response when only pooled response data are collected under different pooling designs. Asymptotic properties of these estimators are investigated and compared. Extensive simulation studies are carried out to compare finite sample performance of the proposed estimators under various model settings and pooling strategies. We apply the proposed local polynomial regression methods to two real-life applications to illustrate practical implementation and performance of the estimators for the mean function.