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Article ? AI-assigned paper type based on the abstract. Classification may not be perfect — flag errors using the feedback button. Tier 2 ? Original research — experimental, observational, or case-control study. Direct primary evidence. Human Health Effects Sign in to save

Effects of Microplastics on Seabird Chicks: An Experiment Using Pellets with and Without Chemical Additives

ORNITHOLOGICAL SCIENCE 2025 1 citation ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Koki Shigeishi, Rei Yamashita, Kosuke Tanaka, Mami T. Kazama, Naya Sena, Hideshige Takada, Yoshinori Ikenaka, Mayumi Ishizuka, Shiho Koyama, Ken Yoda, Yutaka Watanuki

Summary

Wild seabird chicks (Streaked Shearwaters) were experimentally dosed with plastic pellets — with and without chemical additives like flame retardants and UV stabilizers — to measure the physiological effects of microplastic ingestion. Both types of pellets caused measurable harm including increased stress hormones, digestive issues, and lesions, and pellets containing chemical additives caused additional toxic effects beyond the physical burden of the plastic itself. The study provides direct experimental evidence that plastics with chemical additives are more harmful to wildlife than virgin plastics, reinforcing concerns about additive chemicals as a key dimension of the microplastics health problem.

Microplastics ingested by seabirds may decrease digestive ability, increase stress levels, and cause lesions in their digestive tracts. Hazardous chemicals added to and accumulated in these plastics may also pose adverse effects. To examine these effects, two experiments were carried out using wild Streaked Shearwater Calonectris leucomelas chicks. We dosed them orally with either 0.43 g plastic pellets with chemical additives (flame retardant and UV stabilizer), or 2.00, 3.00 and 4.00 g virgin plastic pellets without additives. The dose of pellet loads of up to 0.8% of chick body mass did not affect growth in body mass, structural size, meal mass per day, or plasma stress hormone levels. Pellets with chemical additives, however, appeared to adversely affect liver and kidney masses during their early development, raising the concern of potential toxic effects of chemical additives within the microplastics themselves, in the stomachs of seabirds.

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