INMA: “Exposure to toxic metals may contribute to blood pressure elevation in male adolescents”
A study based on the INMA cohort established in the province of Granada (Southern Spain) assesses the relation of urinary concentrations of seven metallic elements with blood pressure and serum hormone levels in male adolescents aged 15-17 years.
Heavy metals and metalloids are generated mainly from human activities such as mining, smelting, combustion, tannery or fertilizer applications. Humans and animals can be exposed to metals via inhalation, consumption and/or dermal contact. Importantly, metals such as arsenic (As), cadmium (Cd), lead (Pb), mercury (Hg), and nickel (Ni) are associated with a wide range of adverse health effects, such as cardiovascular disorders, neurological disorders, bone and immune effects, respiratory deficits, and cancer. Other metals such as manganese (Mn) and chromium (Cr) are necessary for physiological functions of the human body at low levels but can be hazardous at high levels.
Chronic exposure to As, Cd, Hg, and Pb has repeatedly been associated with cardiovascular disease in the general population. However, few studies have explored this association in adolescents, an age group especially vulnerable to blood pressure elevation and hormonal disturbances. Studies investigating the effects of Pb and Hg in children and adolescents have published inconsistent results, while very few data are available on the effects of other metals. Besides their impact on health, some metals are considered to act as endocrine disruptors, by mimicking the action of hormones, but evidence of an association between metals and hormones remains limited and inconclusive.
The study included 133 boys with available data on urinary metals, blood pressure, serum hormones, and lifestyle information. Blood pressure measurements were taken three times consecutively on the same day after the boy had rested in sitting position for 5 minutes before measurements.
Whole venous blood was collected from participants to measure thyroid hormones (FT4, TT3, and thyroid-stimulating hormone (TSH)); sex steroids (testosterone, 17β-estradiol, and dehydroepiandrostenedione (DHEA)); non-steroidal sex hormones (luteinizing hormone (LH), FSH, SHBG, anti-Müllerian hormone (AMH) and prolactin); adrenal hormones (adrenocorticotropic hormone (ACTH) and cortisol); human growth hormone (hGH); and insulin-like growth factor-1 (IGF-1). Urine samples were collected by participants at home from the first morning void for urinary metals analysis.
Urinary As and Cd were both associated with slight elevations in systolic blood pressure, and urinary As was also associated with an increased risk of elevated systolic blood pressure. The presence of detectable levels of 4 and 5 versus 2-3 non-essential metals (As, Cd, Hg, Ni, Pb) per boy was associated with elevations in systolic blood pressure. Significant associations were also found between Hg and increased testosterone and LH and decreased TSH; between the combination of As and Hg and increased LH and IGF-1; between Cr and decreased TSH; and between Cd and increased ACTH.
Findings suggest that combined exposure to toxic metals, especially As and Cd, at environmentally relevant levels may contribute to blood pressure elevation in male adolescents. The association of metal exposure with hormone levels is less conclusive. Authors say that given the high prevalence of exposure to metals in the general population and the particular vulnerability of adolescents to blood pressure and hormonal changes, these results may have important implications for adolescent health. They plead for research to prospectively explore these associations in larger study populations.
Reference: Castiello F, Olmedo P, Gil F, Molina M, Mundo A, Romero RR, Ruíz C, Gómez-Vida J, Vela-Soria F, Freire C. Association of urinary metal concentrations with blood pressure and serum hormones in Spanish male adolescents. Environ Res. 2020 Mar;182:108958