PFOS, one of the persistent chemicals in the PFAS family, disrupted growth and changed gene activity in a laboratory model designed to reproduce key features of very early human development, according to researchers at Karolinska Institutet.
The work does not show that PFOS exposure causes developmental harm in human pregnancies. Instead, it uses human pluripotent stem cells to examine a stage of development that is difficult to study directly. The findings add to concerns about chemicals that remain in the environment and the body for long periods, while also illustrating how stem-cell systems can be used to investigate potential effects before clinical evidence is available.
A model of the period after implantation
PFAS are a large group of synthetic chemicals used in applications including water-repellent materials, food packaging and cosmetics. Their resistance to breakdown has led to the term “forever chemicals.” That same persistence means they can remain in environmental systems for decades and can accumulate in people over time.
The Karolinska team investigated three regulated but highly persistent PFAS compounds: PFOS, PFOA and PFHxS. They used human pluripotent stem cells to create three-dimensional cellular structures that reproduce several aspects of development shortly after an embryo implants in the uterus.
Among the features represented in the model was the formation of primordial germ cells, which are the precursors of sperm and eggs. This makes the system relevant not only to early embryonic growth but also to developmental processes connected with future reproductive cells.
João Pedro Alves-Lopes, an assistant professor in Karolinska Institutet’s Department of Women’s and Children’s Health and the study’s lead author, said stem-cell-based approaches can help researchers examine how environmental chemicals affect an otherwise hard-to-access period of human development.
PFOS produced the clearest changes
Of the three chemicals, PFOS produced the most pronounced effects in the four-day experiments. Embryo-like structures exposed to the compound grew more slowly and remained smaller than untreated controls.
The effect appeared at the lowest concentration tested: 7 nanomoles per liter. The researchers selected that baseline because it corresponds to PFOS concentrations measured in the blood serum of pregnant women in Sweden’s SELMA study.
Primordial germ cells still formed in the PFOS-exposed structures, but their patterns of gene activity were substantially different from those in the control group. At the baseline concentration, the activity of 746 genes differed from the untreated comparison group.
That result is important because a change in gene expression is not the same as a demonstrated health outcome. It does, however, indicate that the chemical affected cellular programs during a sensitive developmental window in this experimental setting.
What the study can—and cannot—say
The model offers a way to test biological questions in human cells, but it is not a pregnancy and cannot capture every process that occurs in a developing embryo or in the pregnant body. The results therefore should not be read as a direct prediction of outcomes for an individual pregnancy.
Its value is in identifying mechanisms and signals worth investigating further. By comparing PFOS with PFOA and PFHxS under the same general approach, the study also suggests that different members of the PFAS family should not automatically be treated as biologically identical.
The research arrives amid continued scientific and policy attention to PFAS exposure. These compounds are used across many consumer and industrial contexts, and their environmental persistence complicates efforts to reduce contact with them. Studies that can connect exposure-relevant concentrations with changes in human-cell models may help guide the next rounds of toxicology and epidemiological research.
A tool for earlier-stage questions
The study, published in Human Reproduction Open, underscores a broader shift in developmental research: using increasingly sophisticated cell models to investigate questions that cannot be answered easily through direct observation.
For PFOS, the immediate takeaway is caution rather than certainty. The researchers found slower growth and broad changes in gene expression in a stem-cell-derived model, including at a concentration linked to measurements in pregnant women. Further work will be needed to determine how those experimental signals relate to human health outcomes and to clarify why PFOS stood out among the three compounds tested.
But the result strengthens the case for studying persistent environmental chemicals at the earliest stages of development, when small changes in cellular programs may be especially consequential.
This article is based on reporting by Medical Xpress. Read the original article.
Originally published on medicalxpress.com
