Is Zinc safe?

Introduction

Zinc is an essential trace element necessary for various biological functions, including growth, neuronal development, and immune function. However, concerns about its safety, particularly in high doses or specific forms like zinc oxide nanoparticles (ZnO NPs), have been raised. This synthesis aims to evaluate the safety of zinc based on multiple research studies.

Key Insights

General Safety and Toxicity of Zinc:
- Zinc is generally non-toxic at normal dietary levels but can cause toxicity at high doses, leading to symptoms like nausea, vomiting, and fatigue .
- Long-term high-dose zinc supplementation can interfere with copper uptake, leading to copper deficiency and associated health issues .
Zinc Oxide Nanoparticles (ZnO NPs):
- ZnO NPs used in sunscreens do not penetrate the viable epidermis and do not cause local skin toxicity, making them safe for repeated application.
- ZnO NPs are virtually non-toxic in animal models, with no carcinogenic potential and low skin penetration.
- Environmental concerns exist regarding ZnO NPs, as they can cause physical damage, release zinc ions, and generate reactive oxygen species (ROS), affecting various organisms.
Zinc in Environmental Contexts:
- Safe concentrations of zinc for protecting riverine macroinvertebrate diversity are higher than current water quality standards, suggesting that existing standards may be overly protective.
- Zinc toxicity in the environment can alter microbial diversity in soil and water, affecting the bioavailability of other metals.
Zinc and Brain Health:
- Zinc plays a role in neuronal death associated with brain injuries like ischemia and seizures, indicating that while essential, zinc can also contribute to cytotoxic events in the brain .
Zinc in Animal Nutrition:
- Zinc oxide is safe for use in animal feed, with no concerns for consumer safety when used within regulatory limits. However, there are potential environmental concerns related to zinc runoff into groundwater and surface water.

Conclusion

Zinc is generally safe and essential for human health at normal dietary levels. High doses can lead to toxicity, primarily through copper deficiency. Zinc oxide nanoparticles, commonly used in sunscreens, are safe for skin application but pose environmental risks. Regulatory standards for zinc in environmental contexts may be overly conservative. Overall, zinc is safe when used appropriately, but caution is needed with high doses and specific forms like nanoparticles.

Summary

Consensus Meter

Introduction

Key Insights

Conclusion

Sources and full results

The Essential Toxin: Impact of Zinc on Human Health

Zinc deficiency, caused by malnutrition, aging, certain diseases, or deregulated homeostasis, is a more common risk to human health than excessive exposure to zinc, affecting growth, neuronal development, and immunity.

Support for the Safe Use of Zinc Oxide Nanoparticle Sunscreens: Lack of Skin Penetration or Cellular Toxicity after Repeated Application in Volunteers.

Repeated application of zinc oxide nanoparticle sunscreens to the skin is safe, with no evidence of penetration into the viable epidermis or cellular toxicity.

Risk assessment of zinc oxide, a cosmetic ingredient used as a UV filter of sunscreens

Zinc oxide, a common ingredient in sunscreens, is safe for use within current regulatory limits in Korea, with no carcinogenic potential and low skin penetration.

Zinc Essentiality, Toxicity, and Its Bacterial Bioremediation: A Comprehensive Insight

Zinc is essential for human growth and plays a role in protein regulation, but its toxicity can be mitigated through bacterial bioremediation in polluted soil and wastewaters.

Effect of zinc on diversity of riverine benthic macroinvertebrates: Estimation of safe concentrations from field data

The safe concentration of zinc for protecting riverine macroinvertebrate diversity is more than twice the current water quality standard in Japan (30 g/L), suggesting that the standard is likely overprotective for macroinvertebrate diversity.

Toxic effects of different types of zinc oxide nanoparticles on algae, plants, invertebrates, vertebrates and microorganisms.

Zinc oxide nanoparticles have toxic effects on various organisms, mainly due to physical damage, dissolved zinc ions, and ROS-mediated mechanisms.

Zinc toxicity.

Extremely high zinc intake can cause toxicity symptoms, while even low levels can interfere with copper and iron utilization and negatively affect HDL cholesterol levels.

Nanostructures of zinc oxide

Zinc oxide nanostructures show promise for optoelectronics, sensors, transducers, and biomedical science due to their unique properties and bio-safe nature.

Zinc and brain injury.

Reducing extracellular zinc accumulation or vulnerability to toxic zinc exposure may help ameliorate neuronal death in brain injury and neurological diseases.

Scientific Opinion on safety and efficacy of zinc compounds (E6) as feed additive for all animal species: Zinc oxide, based on a dossier submitted by Grillo Zinkoxid GmbH/EMFEMA

Zinc oxide is a safe feed additive for all animal species, with no concerns for consumer safety and no environmental impact, but may affect groundwater and drainage.

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