A Karolinska Institutet single-cell study in eBioMedicine shows MEHP, the breakdown product of the plastic additive DEHP, alters gene expression in all seven human ovarian cell types. The surprise finding is the exquisite sensitivity of glial cells, the ovary's nervous-system cells, to the exposure.

The file on plastic additives and women's reproductive health gained a new page in the first week of October. A Karolinska Institutet team, publishing in eBioMedicine, mapped for the first time at single-cell resolution how mono-(2-ethylhexyl) phthalate (MEHP) , the breakdown product of the phthalate DEHP, acts on human ovarian tissue. According to the full text on ScienceDirect, the work ran inside the Department of Women's and Children's Health, led by Eleftheria Maria Panagiotou with Pauliina Damdimopoulou as senior author.

Realistic dose, six days, seven donors

The design stands out for dose realism: tissues spent six days in MEHP at 20.51 nanomoles per litre, matching levels measured in the general population, alongside a thousand-fold higher concentration. Tissue from seven donors went in; more than 12,000 cells came out read one by one with single-cell RNA sequencing . The result is not an average tissue response but a separate testimony from each cell type.

Across oocyte, granulosa, stromal, perivascular, endothelial, immune and glial cells — all seven types examined — gene expression veered markedly from controls. The hit pathways are familiar but the scope is new: the actin cytoskeleton, cell adhesion , and oxidative phosphorylation , the cell's power plant. This is not one gene switching on or off; it is the skeleton-energy-communication trio shaking at once.

The most exposed link: glial cells

The point Damdimopoulou underlined in the Newswise bulletin is that legacy tests looked only at follicle and egg, whereas on this map glial cells — nervous-system cells whose presence in the ovary was only recently established — proved exquisitely sensitive, with cell-to-cell communication weakening along glial-stromal lines in particular. The picture proposes, for the first time at cell level, a mechanism for the much-discussed link between phthalates and polycystic ovary syndrome.

The signal did not stop at gene expression: shifts in the EIF5A, MT-ND3, MT-ND4L and VCL proteins were confirmed by staining — sequencing on one donor, staining on six. Follow-up runs on primary ovarian cells from three patients and stem-cell-derived Schwann cells backed the glial sensitivity as no accident. In short, two independent methods and two independent cell models pointed the same way.

From laboratory to regulation

As the legal bulletin LawBC reports, the US Environmental Protection Agency published final TSCA evaluations for five phthalates including DEHP on 6 January 2026: DEHP was found an unreasonable risk for ten worker conditions of use and twenty environmental ones. EPA biomonitoring data show phthalate metabolites widely measured in the general population, and a 2019 review in the NIH library PMC documents exposure accumulating via food, air and contact. On the EU side, TheChemCo's 2026 regulation roundup notes REACH caps phthalates at 0.1 percent by weight in toys and childcare articles. Laboratory and statute are looking the same way.

The conclusion: one study changes no policy, but it widens the window. The era of equating ovarian toxicity with the follicle alone is closing; support cells, nerve cells and energy pathways are now part of the assessment. The next step is to wed this cell map to epidemiology and cumulative risk arithmetic.