Common household flame retardants quadrupled cancer risk

Common organic compounds added to plastics, textiles and other materials to make them flame retardant can multiply the risk of dying from cancer. A new US-China study has shown this for the first time.

The work, which was recently published in the journal JAMA Network Open, involves polybrominated diphenyl ethers (PBDEs), a type of organobrominated compounds that are used as flame retardants, i.e. substances that prevent fire. PBDEs are used in the manufacture of products ranging from plastics and building materials to furniture, electronics, aeroplanes and cars.

These chemicals can enter the human body through contaminated household dust, air and consumer products, as well as through food. Once in the environment, PBDEs, which are classified as persistent organic pollutants, migrate through food chains and accumulate in the tissues of higher animals. Researchers have found PBDEs in different fish species from the Baltic Sea, such as herring and cod. The highest concentration of PBDEs was found in the liver of fish.

The toxic properties of polybrominated diphenyl ethers are of course not new. It is known from the scientific literature that they can adversely affect the endocrine and reproductive systems, destroy thyroid hormones and mimic estrogen.

Past studies have shown links between these compounds and metabolic malfunctions, obesity, thyroid disease and certain cancers. In addition, because of their ability to be transmitted to the foetus through the placenta and to newborns through breast milk, PBDEs can lead to neurodevelopmental disorders in children.

A team of researchers from the US and China set out to expand knowledge in this area and traced the link between exposure to PBDEs and all-cause and cause-specific mortality. The scientists used data from the US-based National Health and Nutrition Examination Survey (NHANES) programme. It serves as an average assessment of the health and nutrition of the nation's residents and includes a physiological survey and interviews.

The sample consisted of 1,100 people (average age about 43 years) who had blood tests, including PBDEs, as part of the programme in 2003-2004. This information was then compared to the participants' mortality statistics up to the end of 2019.

Using statistical analysis methods, the scientists found that people with high levels of polybrominated diphenyl ethers in their blood were about four times more likely to die of cancer than participants with minimal levels of PBDEs. This result was obtained after adjusting for age, sex, body mass index, ethnicity, lifestyle and socioeconomic factors. At the same time, the researchers found no significant association between PBDEs and all-cause and cardiovascular mortality.

According to the authors, their findings have important public health implications. Although the Stockholm Convention on Persistent Organic Pollutants largely bans the use of PBDEs, they continue to be actively used. For example, in the USA, restrictions on polybrominated diphenylethers are in force only in 13 states, and there are no restrictions at the federal level.

In Russia, there is no talk of a complete ban on PBDEs either. The new scientific work certainly makes this issue more relevant.