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Diet is one of the two main sources of metals (the other being drinking water), and so it is important to understand how the type and composition of diet affects our exposure to them. The Mediterranean diet is one such dietary type that is commonly associated with being good for health, and it is composed of individual elements such as vegetables, pulses, seafood and meat. It is not clear though, how this dietary pattern might influence exposure to metals.

Thus, in this study the authors sought to investigate whether adherence to a Mediterranean diet affected children’s exposure to metals, and subsequently whether the individual components of this diet that may account for any observed differences.

This study included 2,139 children participating in the INfancia y Medio Ambiente (INMA) study. The INMA study recruited pregnant women from Asturias, Gipuzkoa, Sabadell and Valencia in Spain between 2003 and 2008, and their children were assessed at follow-up when they were between 4 and 5 years old. At this time, the children completed questionnaires about their dietary habits (the “food frequency questionnaire”) and provided urine samples, which were tested for the presence and quantity of metals. The authors also made sure to check for other potential influences on metal exposure, such as age, sex, body mass index, socio-economic status and total energy intake.

The study found that adherence to the Mediterranean diet was associated with higher levels of arsenobetaine, a non-toxic, organically occurring derivative of arsenic, but lower levels of copper, an essential mineral. Overall, the levels of metals reported in this study were lower than those from an Italian study of 5-11-year-old children, although the observed levels of cobalt, zinc and selenium were similar to those of a previous study of 8-14-year-old Mexican children.

Interestingly, further examination by individual components of the diet showed that fish and seafood consumption specifically was associated with higher levels of arsenobetaine, which is consistent with previous reports. On the other hand, there was no clear reason for reduced levels of copper, although consumption of meat in the study group was almost 30% less than that reported in similar aged children across the whole of Spain, which may have played a role. In addition, while urine samples are an acceptable measure of copper concentration, they may not be the most accurate means of assessment, so results must be interpreted with caution.

An additional consideration is that this study was cross-sectional in design, which means that dietary adherence and metals were measured at the same point in time. A stronger design is a longitudinal study, which means measuring diet and metals in the same people at several points in time. Such a design provides stronger evidence but takes more time and resources. The study reported here provides evidence to support the conduct of a longitudinal study in this field of research at future points in follow-up.

Ultimately, the authors concluded that this study shows that adherence to the Mediterranean diet increases exposure to some metals but reduces exposure to others, and that it highlights the importance of considering individual components of the diet when assessing its impact.

Reference: Notario-Barandiaran L, Irizar A, Begoña-Zubero M, Soler-Blasco R, Riutort-Mayol G, Fernández-Somoano A, Tardón A, Casas M, Vrijheid M, Meharg A, Carey M, Meharg C, Ralphs K, McCreanor C, Grimalt JO, Vioque J, Signes-Pastor AJ. Association between mediterranean diet and metal(loid) exposure in 4-5-year-old children living in Spain. Environ Res. 2023 Sep 15;233:116508.

Link to scientific article: https://pubmed.ncbi.nlm.nih.gov/37392824/

The term ‘metabolic syndrome’ (MetS) describes a group of factors, such as abdominal obesity, hypertension and insulin resistance, that increase the risk of cardiovascular disease and type 2 diabetes. A new study suggests that exposure during pregnancy to a combination of endocrine disrupting chemicals (EDCs) is related to a poorer metabolic health in childhood, which can contribute to an increased risk of metabolic syndrome in adulthood. The research, led by the Barcelona Institute for Global Health (ISGlobal), a centre supported by the “la Caixa” Foundation, has been published in Jama Network Open.

EDCs interfere with the functioning of our hormonal system, growth, energy balance and metabolism and whose exposure is difficult to escape. Previous studies have already shown a link between individual exposure to some of these compounds during the prenatal phase and some of the factors that make up the metabolic syndrome, particularly obesity and blood pressure. As part of the ATHLETE project, the ISGlobal team looked at the combined impact of these substances on all metabolic syndrome factors.

The study involved 1,134 mothers and their children from six European countries (the INMA cohort from Spain, EDEN from France, RHEA from Greece, KANC from Lithuania, MOBA from Norway and BIB from the United Kingdom), all volunteers from the HELIX (Human Early Life Exposome) cohort. Prenatal exposure to 45 EDCs was analysed through blood and urine samples collected from the mothers during pregnancy or from the umbilical cord after birth.

Later, when the children were between 6 and 11 years old, they were followed up, and information on waist circumference, blood pressure, cholesterol, triglycerides and insulin levels were collected and summarized to obtain a risk index for metabolic syndrome.

Mercury, PFAS, organochlorine pesticides and PBDEs

Statistical analysis showed that mixtures of metals, perfluoroalkylated and polyfluoroalkylated substances (PFAS), organochlorine pesticides and flame retardants (or PBDEs) were associated with a higher risk of metabolic syndrome. In the case of metals, the association observed was mainly due to the effect of mercury, of which the main source of intake is large fish.

PFASs are one of the most widely used families of chemical compounds, used in pesticides, paints, non-stick pans or fast food packaging, among many other common uses. Due of their persistence, they are also known as the ‘forever chemicals’. Organochlorine pesticides, also very persistent, were already banned in Europe in the 1970s, but we are still widely exposed due to their permanence in the environment.

Different results according to sex

“We also observed that associations were stronger in girls for mixtures of PFASs and polychlorinated biphenyls (PCBs), while boys were more susceptible to exposure to parabens. Since endocrine disruptors interfere with sex steroid hormones, these differences fall within what would be expected”, explains Nuria Güil Oumrait, ISGlobal researcher and first author of the study.

“Our results suggest that exposure to widespread mixtures of endocrine disruptors during pregnancy may be associated with adverse metabolic health in both boys and girls. This association may contribute to the current increase in the prevalence of lifetime metabolic syndrome, which currently affects 25% of the adult population, with upward trends evident even among young people”, concludes Martine Vrijheid, co-director of ISGlobal’s Environment and Health over the Lifespan programme and senior author of the study.

Reference: Güil-Oumrait N, Stratakis N, Maitre L, Anguita-Ruiz A, Urquiza J, Fabbri L, Basagaña X, Heude B, Haug LS, Sakhi AK, Iszatt N, Keun HC, Wright J, Chatzi L, Vafeiadi M, Bustamante M, Grazuleviciene R, Andrušaityte S, Slama R, McEachan R, Casas M, Vrijheid M. Prenatal Exposure to Chemical Mixtures and Metabolic Syndrome Risk in Children. JAMA Netw Open. 2024 May 1;7(5):e2412040.

Link to scientific article: https://pubmed.ncbi.nlm.nih.gov/38780942/

We have had 120 registered participants and the presentation of 42 scientific papers carried out with data from the INMA Project.

Thank you very much to all of you for your participation and see you next year.

Collaborators:

• FINAL Scientific Program: Link

• Format: Plenary sessions and presentation of INMA results in person on 11 and 12 June at the Barcelona Biomedical Research Park – PRBB, Barcelona (will be broadcast in Streaming) Book these dates! We are waiting for you!

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Collaborators:

Organochlorine pesticides (OPs) and polychlorinated biphenyls (PCBs) are groups of environmental chemicals that are part of the known endocrine disruptors, with the ability to mimic hormones and inducing adverse effects in exposed individuals or their offspring. Due to their toxic, persistent, and bioaccumulative properties, OPs and PCBs contribute to exposure to persistent organic pollutants (POPs), which are strictly regulated by international laws (Stockholm Convention). Historically, they were used in agriculture as pesticides, in public health for control insect vectors, and in multiple industrial processes such as electrical transformer manufacturing. The accumulation in the mother’s body and prenatal and early exposure to these environmental contaminants are related to child health and developmental issues and predispose to harmful effects in adulthood. Additionally, children are especially vulnerable to air, water, and soil contaminants as they are in the growth process and their immune system and detoxification mechanisms are not fully developed. Therefore, it is crucial that the environment in which they develop, from conception to adolescence, be protected to ensure their health.

International human biomonitoring programs for environmental exposure, such as NHANES in the United States and HBM4EU in Europe, have highlighted the widespread exposure of humans to numerous environmental chemicals. However, despite the measures taken in the Stockholm Convention on Persistent Organic Pollutants (2009), surveillance of exposure to POPs and associated diseases remains extremely limited in Latin America and other regions of the world.

What does this study add to the available literature?

Given the lack of data in Latin America, we transferred what was learned in the INMA Cohort to a maternal-infant cohort of Panamanian mothers and children (PA-MAMI), which tries to evaluate environmental exposure in early stages of development and the possible adverse impact of Environment and diet in early childhood in Panama.

Our study is pioneer in assessing the concentrations of OPs and PCBs in placenta samples from Latin American women, as well as quantifying hormone activity related due to the combined effect of POPs exhibiting estrogenic hormonal activity. The use of placenta as a biological matrix is of great relevance, as it is recognized as a valuable and readily available source of human tissue for biomonitoring chemical exposure between mother and child. Additionally, it allows for the implementation of effect biomarkers without the limitation of available tissue quantity.

The results of this study reveal that all placenta samples from Panamanian mothers analyzed were positive for at least three POP residues, with over 70% positive for at least six of them. The frequencies of quantified OPs ranged from 100% for p,p’-DDE and HCB to 30.8% for β-HCH, with the highest median concentration observed for lindane (380.0 pg/g of placenta). The detection frequency of PCBs ranged from 70.0 to 90.0%; the highest median concentration was observed for PCB 138 (17.0 pg/g of placenta), followed
by PCB 153 (16.0 pg/g of placenta). Furthermore, all placentas tested positive in the estrogenicity bioassay, highlighting that exposure to lindane was positively associated with estrogenicity, while this association was negative in the case of exposure to PCB 153. Regarding exposure predictors, higher concentrations of p,p’-DDE were associated with increased meat consumption, suggesting that animal fat is an important source of exposure to DDT metabolites.

What are the implications of the results obtained?

The data obtained in the PA-MAMI cohort study can be use as a reference for biomonitoring chemical exposure during pregnancy and its impact on offspring health in Panama and other Central American countries. They are also useful in emphasizing the need to estimate the cocktail effect of environmental contaminants, where exposure to low concentrations may result in undesirable and unsuspected combined effect when considering contaminants individually. Furthermore, these results can help the implementation of legal regulations that reduce exposure to environmental contaminants, which would help prevent possible risks to children’s health and where periodic biomonitoring would allow exploring the effectiveness of such regulations.

Reference: Iribarne-Durán LM, Castillero-Rosales I, Peinado FM, Artacho-Cordón F, Molina-Molina JM, Medianero E et al. Placental concentrations of xenoestrogenic organochlorine pesticides and polychlorinated biphenyls and assessment of their xenoestrogenicity in the PA-MAMI mother-child cohort. Environmental Research 2024; 241:117622.

Link to scientific article: https://pubmed.ncbi.nlm.nih.gov/37977273/

Luz María Iribarne Durán
Doctora en Medicina Clínica y Salud Pública
Nicolás Olea
Catedrático Facultad de Medicina/Facultativo Especialista Hospital Clínico
Universidad de Granada/Hospital Clínico S. Cecilio
Instituto de Investigación Biosanitaria de Granada (ibs. GRANADA)