Resumen de Vies d’exposició a compostos organoclorats i metalls en infants
The present research assesses some of the main routes of exposure to various pollutants, specifically organochlorine compounds (OCs) and trace metals, in infants. It focuses on three populations, located in southern Europe: Menorca, Asturias and Tarragona. These three cohorts have served as a population model to evaluate exposure through diet, environment and mother-child transfer during pregnancy, respectively.
A chemical analysis has been carried out in more than 600 serum and urine human samples, along with food products to determine a wide range of OCs and trace metals. This was undertaken using Gas Chromatography with Electron Capture Detector (GC- ECD) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS), respectively.
The most remarkable results of this Ph.D. are described below. Half of the fish caught in the Mediterranean Sea have exceeded the levels of mercury established by the European Union for human consumption. Likewise, the estimated ingestion of mercury in the cohort of Menorca has also exceeded tolerable intakes established by the European Food Safety Authority (EFSA), with being the main source of incorporation of this metal (approximately 80%). Conversely, concentrations of OCs in foods have been well below the established limits. It has been observed that weight and trophic level of fish are key factors in the accumulation patterns of these compounds, due to the bioaccumulation and biomagnification processes.
On the other hand, the levels of trace metals in the population of Asturias have been higher than those found in previous studies. This is likely a result of the high industrial and mining activity in the area. In this cohort, the high concentrations of arsenic in urine with fish consumption has also been identified. This form of arsenic, though, is not toxic. An inversely significant correlation, however, between levels of urinary cobalt and ferritin in the blood has been observed. In situations of higher iron demand -as occurring during the growth stage in which these children are - the body increases the expression of the DMT1 divalent ion transporter, which also incorporates cobalt. It has also been observed that cobalt concentrations are much higher in children with iron deficiency anaemia.
Finally, in the cohort of Tarragona, a significant increase in OC concentrations in maternal serum has been found for the first time between the first trimester of pregnancy and childbirth. This is likely due to a mobilization of the fat reserves and the increase in blood volume during this period. The levels of OCs measured in cord blood have been significantly correlated with the concentrations of these compounds in maternal serum. This distribution is the result of a predominantly maternal source that transfers contaminants to the foetus. The age and the body mass index of mothers have been determined as the main factors that determine the concentrations of OCs in the human body.
From a point of view of public health and environmental regulation, special attention must be given to these pollutants; due to their persistence in the environment and the ease of incorporation into the human body- mostly thorough the diet and reparation. Despite most of the studied compounds currently being banned or strictly controlled, this study confirms the presence of these pollutants already in the early stages of childhood life. This highlights the need to expand research on the factors that determine the environmental distribution and human exposure. Through this, it is anticipated that there will be an improvement in the health of the population; as a result of the advances in available information.
