Most Oral Nanoplastics Leave Hens in Excreta—But Organs Still Show Signal, ACS Nano Study Shows

A new ACS Nano study followed radiolabeled polystyrene nanoplastics through laying hens and found that most of an oral dose left the birds in their excreta within a week. Even so, the researchers detected signal in several organs. The paper was published 15 October 2026 by a team from Zhejiang University and the University of Hawaiʻi at Mānoa, among others. It is a hen study with experimental dosing. It is not a drinking-water study.

What the researchers did

The team gave laying hens polystyrene nanoplastics labeled with carbon-14 (14C) in the backbone of the plastic, at 0.4 mg per kg of body weight per day. The authors describe that dose as chosen to represent an environmentally plausible upper-bound exposure scenario. The particles had a primary diameter of about 80 nanometers in dry form, and the dried dosing material showed micrometer-scale clumping when redispersed, the authors note. Because the label is radioactive carbon, the team could build a quantitative whole-body "fate map" and a mass balance. In a separate 21-day dietary study, hens received 0.4 and 2 mg per kg per day to look at intestinal responses.

What they reported

• Most of the dose left in excreta. Excreta accounted for about 88.6% of the cumulative administered dose after 3 days and about 90.1% after 7 days.
• The gut held the largest remainder. Gastrointestinal contents were the largest non-excreted compartment.
• Organ signals. Among internal organs, kidney, liver and lung showed the most prominent 14C signals.
• Brain by day 7. Trace brain-associated 14C was below the method's detection limit at day 3 but quantifiable at day 7.
• Eggs. The overall egg-associated signal stayed below 0.1% of the cumulative administered dose.
• 21-day arm. The authors report intestinal histopathological changes, elevated permeability markers, and pro-inflammatory and oxidative-stress readouts in hens, with shifts in cecal microbiota most evident at 2 mg per kg per day.

What to keep in mind

• This is an animal study in laying hens.
• The nanoplastics were fed to the birds under experimental conditions. The study did not test drinking water, tap water or bottled water.
• The signal is a measure of the radiolabel (14C) location; it is not a count of intact particles.
• The paper reports where the labeled material went and what the hens' tissues showed. It does not offer advice about what to eat or drink.

Why we are covering it

Nanoplastics and microplastics research has mostly asked what is out there. Quantitative studies of what happens after an oral dose, including how much simply passes through, help put detection results in context. This one is a food-chain animal model, and it is early science.

Source: Chen, Chen, Wang et al., "14C-Enabled Quantitative Fate Mapping of Orally Administered Polystyrene Nanoplastics in Laying Hens," ACS Nano, published 15 October 2026, pubs.acs.org/doi/10.1021/acsnano.6c09648 (DOI 10.1021/acsnano.6c09648).

WaterVO™ News summarizes new nanoplastics and microplastics research for general readers. This item is for information only. More at watervo.com.