Review of Health Hazards in High-Entropy Alloy Processing Under Laboratory Conditions and Risk Assessment Using a Simple Risk Scoring Model.

Certain metal powders used in the synthesis and processing of high-entropy alloys (HEAs) pose significant health hazards, as many of these metals are toxic substances with no biological role in the human body. These metals can mimic essential elements or interfere with metabolic processes (the chemical reactions in living organisms that sustain life), leading to detrimental health effects. While some metals, such as aluminum, can be eliminated from the body through natural biological processes, others tend to accumulate, causing chronic illnesses over time. This review examines the toxicity mechanisms and health impacts of metals used in HEA synthesis, focusing on laboratory-scale processing. It also identifies potential health risks associated with occupational exposure in laboratory environments, including the inhalation of toxic metal powders and nanoparticles. A simple risk scoring model is introduced to systematically assess and quantify these risks based on factors such as toxicity levels, exposure limits, and carcinogenic potential (the ability of a substance to cause cancer) as given by the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) standards. The proposed model can be applied to evaluate the relative hazards of commonly used HEA constituent powders (e.g., Ni, Co, Cr, and Al), offering practical guidance for safer laboratory handling and material selection. By integrating this risk assessment framework, this review aims to enhance workplace safety, guide the development of better material handling practices, and assist researchers in mitigating health risks associated with HEA processing.