Zinc exposure highlights importance of marine nanotoxicology


The effect of exposure to zinc anions and nanoparticles (Zn NP) on mussel Mytilus galloprovincialis was written in the journal Science of The Total Environment to explore the impact of heavy metals on the marine environment.

Study: Impacts of dissolved Zn and nanoparticle forms in the fatty acid landscape of Mytilus galloprovincialis. Image Credit: Solarisys/Shutterstock.com

Metal scrap in the ocean

Wastes containing metals are frequently dumped into the ocean, posing a serious health risk to aquatic life. Trace metals, which are deposited in the air by aerosols such as dust and other particles, have a significant effect on ocean biota, impacting biological productivity and altering coastal ecosystems.

Metallic trace elements can begin to cause different levels of toxicity in marine biota, depending on their physicochemical characteristics. Once inside a species, metals can cause a host of problems, often by triggering an excess of reactive oxygen species (ROS) through Fenton-like reactions. This can damage the body’s lipids, proteins and DNA.

Evidence of toxicity

An overwhelming amount of ecotoxicological studies examine the deposition of pollutants inside a life form, as metals can easily bind to cell surfaces or enter cells by endocytosis.

Pollutants have also been shown to cause changes in lipid respiration and fatty acid profiles, including changes in the percentage of saturated fatty acids versus unsaturated fatty acids, and even some LC-PUFA materials.

Lipid peroxidation occurs when metal-generated ROS interact with PUFAs, causing oxidative stress on these particles and the production of malondialdehyde (MDA), the most common lipid peroxidation component.

Changes in phospholipid and triglyceride synthesis and mobilization and membrane spontaneity are all considered viable evidence of toxicity.

Zinc concentration in water and effect on humans

Due to its widespread uses, commercial importance and inherent characteristics, zinc has been identified by the OECD as one of the major anthropogenic introduced metallic materials.

Zinc nanoparticles can be found in cosmetics, livestock feeds and fertilizers and are frequently used in sunscreens because they can block UV light, thereby protecting skin cells. Due to the widespread and ever-increasing production and use of zinc, several researchers decided to measure it in aquatic environments.

They estimated that zinc alone would contribute 170 to 2,985 tonnes per year to receiving waters of all types. Zinc NP concentrations in European surface waters are expected to be around 1 mg/L by 2020.

The result shows different effects on the molds

The team found that the absorption percentages of nano-zinc and ionic zinc were very different, with nano-zinc accumulating at a much higher rate.

The results revealed that zinc has obvious detrimental effects on mussels Mytilus galloprovincialis, both in anionic and nanoparticle configurations. These effects are proportional to the time and the concentration of irradiation.

The concentration levels tested in this study are mathematically possible to achieve in nature, at least in some places closer to the disposal of domestic wastewater. Consequently, the toxic effects produced are of concern, as there is a high risk of negative consequences on marine biota chains and, inevitably, on human health.

This is especially important considering how fishing industries have increasingly sought multiple sources of protein in recent years.

The negative effect of mussels exposed to ionic zinc and the benefit of detection

To summarize, the most toxic effects are correlated with an increased concentration of a metallic stressor, and prolonged exposure worsens the biological effects. Additionally, the negative effects seen in mussels subjected to both the ionic form of zinc and its nanomaterial counterpart underscore the importance of toxicity testing that examines different aspects of the metals.

Metal atoms are increasingly being introduced into aquatic habitats. The negative impacts they can have on biota, such as lipid peroxidation and changes in fatty acid profile, can affect microbes at a higher trophic level, ultimately affecting human health.

Future research

A canonical evaluation of the primary coordinates of fatty acid profiles revealed strong distinction between samples treated with various doses of ionic and nano-zinc, indicating high potential for its use as an indicator set of zinc exposure. Given the existing challenges in determining pollution by micrometallic forms, this discovery offers new possibilities for future environmental monitoring.

Continue reading: Why nanotoxicology should be the first step towards a nanotechnology future.

Reference

Roma, J., et al. (2021). Impacts of dissolved zinc and nanoparticle forms in the fatty acid landscape of Mytilus galloprovincialis. Available at: https://doi.org/10.1016/j.scitotenv.2021.152807

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