DDT levels have declined in humans, environment since 2004; but those of other persistent organic pollutants rising: UN

Dichloro-diphenyl-trichloroethane (DDT), the notorious synthetic insecticide, has declined in humans and the environment since 2004 due to tight regulation globally, along with 11 other Persistent Organic Pollutants (POPs), a new study said on June 17, 2024.

POPs are linked to cancer, liver damage, decreased fertility, and increased risk of asthma and thyroid disease due to their endocrine disrupting properties.

However, other POPs are present everywhere. Worse, replacements for lethal POPs — often banned later due to their similar properties — have also been detected at high levels, according to the report.

Behind the Global Monitoring Plan: In conversation about monitoring persistent organic pollutants (POPs) has been implemented by the UN Environment Programme (UNEP) and funded by the Global Environment Facility (GEF)

It has been published as governments gather this week in Geneva for an ad hoc open-ended working group on the establishment of a science-policy panel on chemicals, waste and pollution prevention.

The report stressed the importance of POP monitoring, caution in introducing alternatives, and addressing gaps in awareness and regulation.

The study

The study was conducted across 42 countries in regions where data on POPs is limited, in order to monitor 30 POPs listed under the Stockholm Convention as of 2021.

The regions included Africa, Asia, Latin America and the Caribbean, and the Pacific Islands.

Samples were collected between 2016 and 2019. The 30 POPs to be monitored included pesticides and industrial chemicals. Also, among them were unintentionally released POPs, which are by-products of industrial processes and from incomplete combustion (e.g., open burning of waste).

“They were found in every one of more than 900 collected samples, with over 50,000 data points generated on POPs in air, water, human milk, soil, beef, milk, milk powder, butter, mutton, pork, chicken, eggs, fish and shellfish, oil, and other items,” according to a statement by the UNEP.

The levels of 12 POPs including DDT have declined globally, according to the data. These 12 were initially listed in the 2004 Stockholm Convention.

The report attributes the decline to regulatory actions implemented since 2004 to control the levels of such chemicals. For instance, DDT – once deployed in agriculture and now highly restricted — has decreased in human milk samples by over 70 per cent since 2004 on global average. But it still remains the most prevalent POP in human milk, particularly in countries where it was intensively used.

Worrying trend

Other POPs continue to be present everywhere. For instance, dieldrin and polychlorinated biphenyls (PCBs), which have been regulated for long, were detected at elevated levels in the air across the African continent, the Caribbean, and Latin America, according to the report.

But even more worryingly, the chemical replacements for banned POPs — which were found to have similar properties later — have also been detected in high levels.

The report particularly highlighted per-and polyfluoroalkyl substances (PFAS). 

“Of the thousands of PFAS, three key chemicals (PFOS, PFOA, PFHxS) are listed under the Stockholm Convention. All of them were found in human milk. PFAS were also found in drinking water in remote islands, in levels far exceeding European Union and United States standards,” the UNEP statement said.

It added that newly listed POPs were increasingly difficult to monitor, even by the world’s top laboratories.

“While data collection is improving, with more labs in low-income countries participating in POPs monitoring, including in the UNEP global interlaboratory assessments, the quality of POPs analysis must continue to improve,” the statement outlined.

“Governments need not be pulled into a toxic game of hide and seek, where one regulated POP is replaced with a new one. This troubling pattern means these substances are still present in products we use, eat, wear, as well as in our air and water,” it quoted Jacqueline Alvarez, chief of the Chemicals and Health Branch of UNEP.

“This highlights the risk of regrettable substitutions of banned POPs and the need to prioritise sustainability in industrial product design and consumer behaviour,” Alvarez added.

“POPs remain omnipresent, despite efforts to reduce their use and production,” said Andrea Hinwood, UNEP’s chief scientist. “Monitoring the concentrations of POPs in the environment and in our own bodies is vital, especially in low- and middle-income countries, to support their assessment of contamination, emissions, and exposure to POPs for informed decision making.”