More than 52 million tonnes of plastic waste are emitted around the world every year, according to a study published in Nature that inventories plastic pollution in 50,702 cities. It concludes that littering is the largest source of plastic emissions in the global North, and uncollected waste is the largest source in the South.  

The use of GLP-1 analog diabetes drugs-such as semaglutide, sold under the trade name Ozempic-is not linked to an increased risk of suicide, according to two studies published in JAMA Internal Medicine. The first, led by a U.S. team, analyzes data from more than 3,300 people who have participated in clinical trials. The second analyzes data from 124,517 users of these drugs in Sweden and Denmark, and compares them with an even larger group of people who used another type of diabetes medication.

The radiation exposure from mobile phone use does not increase the risk of brain cancer, with evidence of “moderate” certainty, according to a systematic review, funded in part by the WHO and published in Environmental International. Exposure from fixed-site transmitters (like broadcast antennas) is also not associated with childhood leukaemia.

Mice with Alzheimer's disease are more resistant to the development of colorectal tumors, a study shows. An inverse relationship between Alzheimer's and cancer has already been shown in epidemiological studies in humans. An imbalance in certain intestinal bacteria contributes to this negative correlation in mice, adds the article published in PNAS.

In a study published in the journal Nature Medicine, a team of researchers from the National Center for Cardiovascular Research (CNIC) proposes a new cardiovascular risk factor to add to those already known. It is clonal hematopoiesis, a phenomenon caused by acquired mutations in blood stem cells. Furthermore, in a separate study published in the European Heart Journal, they suggest that the drug colchicine could serve to reduce its effects.

An international team of researchers publishes a review of the complex environmental impacts of genetically modified crops in the journal Science. According to the study, widespread adoption by some of the world's largest agricultural countries has had mixed results for biodiversity, deforestation and human health, depending on the specific characteristics of these crops and the regions involved. 

An international team with Spanish participation has developed a database with the metagenome of bacteria, fungi, and yeasts present in more than 2,500 foods, mostly dairy products, followed by beverages and fermented meats. The authors identified more than 10,800 microorganisms, half of which were previously unknown species. The study, published in Cell, shows that food-associated microorganisms are present in 3% of the adult gut microbiome and 56% of that of newborns.

Coastal cities around the world appear to be adapting slowly to the effects of climate change and are relying on past and present experiences rather than projections of future risks, according to a systematic review published in Nature Cities.

The sperm of men infected with high-risk genotypes of the human papillomavirus (HPV) suffers more damage from oxidative stress and has a weaker immune response, which can lead to reduced fertility. This is one of the conclusions of a study published in the journal Frontiers in Cellular and Infection Microbiology. The research compared the semen of 20 adults infected with high-risk genotypes, seven infected with low-risk genotypes, and 43 adults without infections.

Analysis of 1,500 climate policies implemented in 41 countries over the last two decades - between 1998 and 2022 - shows that a small proportion - 63 of them - achieved a significant reduction in carbon dioxide emissions. The study, published in Science, indicates that a significant decrease in these emissions was recorded in the transport sector in Spain. According to the authors, the combination of several policy instruments is often more effective than the use of single measures.