Miguel Motas

A model has analysed mercury concentrations in rivers around the world from 1850 to the present day. The results, published in Science Advances, conclude that levels have doubled and even tripled since the Industrial Revolution: before 1850, rivers carried approximately 390 metric tonnes of mercury to the oceans each year, and today that figure has risen to around 1,000 metric tonnes. According to the authors, these results have implications for human health and wildlife, as mercury compounds are neurotoxic, can accumulate in fish and pose a health risk through consumption.

Lead exposure in children can affect their neurodevelopment. In the United States, the maximum blood concentration limit for this metal was lowered to 3.5 μg/dL (micrograms per decilitre) in 2021, down from 10 μg/dL in 2012. Now, a study has analysed data from more than 300,000 children in Iowa and found an association between higher concentrations and poorer school performance in reading and maths, even below the 3.5 μg/dL limit, prompting the researchers to reconsider this figure. The results are published in the journal JAMA Network Open.

Up to 1.4 billion people may be living in areas with soil contaminated by heavy metals such as arsenic, cadmium, cobalt, chromium, copper, nickel and lead, according to research published in Science. The paper, which used data from more than 1,000 studies, estimates that 14-17% of farmland worldwide could be contaminated by at least one toxic metal. Cadmium is the most widespread, especially in South and East Asia, parts of the Middle East and Africa.

An international team of researchers has analyzed various data sources and scientific literature and identified 3,601 chemical substances in human samples such as blood, urine or breast milk that are known to be in contact with food, for example, because they are used in packaging. According to the authors of the study, “this work shows that food contact materials are not completely safe, even if they comply with regulations, because they transfer known substances to food". The research is published in the Journal of Exposure Science and Environmental Epidemiology.

Heavy metals - including arsenic, cadmium and mercury - may adversely affect the ovaries of women approaching menopause, a study claims. Those with high levels of metals in their urine had lower levels of anti-Müllerian hormone, indicating diminished ovarian reserve - fewer oocytes in the ovaries compared to other women of that age. The authors, whose study is published in The Journal of Clinical Endocrinology & Metabolism, used urine data from more than 500 women in the US up to 10 years before their last menstrual period.