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Exposure to Silver and Titanium Dioxide Nanoparticles at Supra-Environmental Concentrations Decreased Sperm Motility and Affected Spermatozoa Subpopulations in Gilthead Seabream, Sparus aurata

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Oliveira et al. expose gilthead seabream sperm samples ex vivo to silver nanoparticles (AgNPs) and dissolved Ag+ ions at concentrations ranging from environmentally realistic (0.25 µg/L) to supra-environmental (250 µg/L), and to titanium dioxide nanoparticles for comparison. Silver NPs and Ag+ ions significantly reduced total and progressive sperm motility at all tested concentrations, while TiO2 NPs affected motility only at the two highest concentrations.

Key numbers

  • AgNP concentrations tested: 0.25 µg/L (realistic), 25 µg/L, and 250 µg/L (supra-environmental) (abstract, body text).
  • Ag+ ion concentrations tested: 0.25, 25, and 250 µg/L (abstract).
  • Effect: total and progressive motility significantly reduced at all three AgNP and Ag+ concentrations (abstract).
  • Fast sperm subpopulation reduction: from 53.4% in controls to 34.8% with AgNP 250 µg/L and 45.0% with Ag+ 250 µg/L (abstract).
  • TiO2 NP concentrations tested: 1, 10, 100, 1000, and 10,000 µg/L; motility effects only at the two highest (1,000 and 10,000 µg/L) (abstract).
  • AgNP mean particle diameter: 19.34 +/- 6.72 nm (abstract).
  • TiO2 NP mean diameter: 21.50 +/- 8.27 nm (abstract).

Methods (brief)

Sperm from mature male seabream were collected and incubated with nanoparticles in non-activating medium (0.9% NaCl) for 1 hour. Motility was measured by computer-assisted sperm analysis (CASA). Sperm subpopulations were identified by two-step cluster analysis of motility parameters.

Evidence fitness

Supports documentation of silver nanoparticle reprotoxicity in a marine fish model at concentrations that include the realistic environmental range. This paper is relevant to hazard characterization of silver nanoparticles released into marine environments. The finding that even 0.25 µg/L AgNPs reduced seabream sperm motility is notable for environmental risk assessment. The paper does not measure silver in edible fish flesh and does not address human dietary exposure.

Limitations

Ex vivo exposure; sperm cells were isolated from the fish before exposure, which does not replicate in vivo route of exposure or bioavailability. Single species; temperate marine context (Iberian Peninsula). No dose-response analysis connecting sperm motility effects to population-level reproductive outcomes.

Update history

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