In the jewelry market, silicone and plastic, thanks to their low cost and ease of processing, have become mainstream materials for beads and ornaments. However, consumers often raise concerns about the safety of these materials: Do these two materials truly live up to the rumored "toxic" label? This article will analyze the safety differences between the two from a scientific perspective.
Silicone as an Inert Material
Chemical Stability Lays the Foundation for Safety
Silicone's core component is silicon dioxide (SiO₂), an amorphous, highly active adsorption material. The silicon-oxygen (Si-O) bond energy in its chemical structure is as high as 466 kJ/mol, far exceeding the bond energy of ordinary organic compounds. This makes silicone virtually unreactive at room temperature. Experimental data shows that silicone maintains structural stability within a temperature range of -40°C to 230°C, making it a preferred material for medical-grade products such as baby pacifiers and breast implants.
Processing to Control Toxicity Risks
Regular silicone products must pass three safety checks:
Raw Material Purity: Medical-grade silicone must contain heavy metals (such as lead and mercury) below 0.1 ppm;
Vulcanization Process: A platinum vulcanization system is used instead of traditional peroxide vulcanization, reducing volatile residues by over 90%;
Post-processing Testing: FDA (U.S. Food and Drug Administration) testing under 21 CFR 177.2600 ensures the absence of endocrine disruptors such as phthalates and bisphenol A.
Usage Limitations
Although silicone itself is non-toxic, two risks should be considered:
Blue Silicone Beads: Color-changing silicone containing cobalt oxide (CoO) may release cobalt ions. Ingestion requires immediate medical attention;
Inferior Recycled Silicone: Some small workshops use recycled tire rubber powder for adulteration, resulting in polycyclic aromatic hydrocarbon (PAH) levels exceeding the permitted limit by over 10 times.
Universal Plastics
The Toxic Trap of Plastic Additives
The hazards of plastic jewelry primarily stem from three types of additives:
Plasticizers: Diisophthalate (DEHP) can increase plastic's flexibility by 300%, but it can interfere with human hormone secretion. Studies have shown that children exposed to DEHP-containing plastic beads over a long period of time have a 2.3-fold increased risk of precocious puberty.
Bisphenol A (BPA): Used in rigid plastics such as PC, it releases more rapidly at temperatures above 80°C. Animal studies have shown that BPA can increase prostate weight in mice by 40%.
Heavy Metal Stabilizers: Stabilizers containing cadmium and lead can increase plastic's heat resistance by 50%, but they can increase blood lead levels in children by 3.7-fold.
The Double-Edged Sword Effect of Processing
Regular plastic jewelry must comply with GB 4806.7-2023, "Plastic Materials and Articles for Food Contact," but the current market situation is worrying:
Abuse of recycled materials: A random inspection of one market revealed that 32% of plastic beads were produced from recycled medical waste, with total bacterial counts exceeding the standard by 150 times;
High-Temperature Precipitation: Polypropylene (PP) is stable at 100°C, but polystyrene (PS) begins to release styrene monomer at 65°C, a substance classified as a Class 2B carcinogen by the International Association for Research on Cancer (IARC);
Colorant Risks: Plastic beads containing azo dyes can decompose into 24 aromatic amines within 48 hours under ultraviolet light, of which benzidine is 10 times more carcinogenic than tobacco.
The Invisible Threat of Microscopic Particles
Plastic jewelry can generate microplastics (<5mm) when worn:
Skin contact: Friction-induced microplastic shedding can reach a rate of 0.3mg/day, entering the bloodstream through hair follicles;
Oral contact: Children can ingest 12,000 microplastic particles per hour when chewing plastic beads;
Environmental accumulation: It takes 450 years for each gram of plastic jewelry to degrade in the natural environment, continuously releasing microplastics and polluting the ecosystem.
Three Criteria for Safe Jewelry
Certifications and Markings Prioritized
Select products with the following markings:
Silicone: FDA certification, LFGB certification, China GB 4806.11-2016;
Plastics: EU CE certification (RoHS Directive (Restriction of Hazardous Substances)) and REACH (Registration of 197 Substances of Very High Concern).
Usage Adaptation
Children's jewelry: Prefer silicone beads (must pass EN71-3 testing) and avoid plastic beads.
High-temperature environments: For car ornaments, choose silicone (temperature resistant to 230°C) and avoid PC/PS plastics.
Long-term contact: For bracelets, choose platinum-cured silicone and avoid PVC containing DEHP.
Daily Maintenance Tips
Silicone jewelry: Disinfect with 5% saline monthly. Avoid contact with oil and grease (which may reduce adsorption).
Plastic jewelry: Stay away from alcohol (which may dissolve some plasticizers) and use a neutral detergent when cleaning.
General Guidelines: Discard damaged jewelry immediately to prevent exposure to internal additives.
The toxicity difference between silicone and plastic is essentially a trade-off between inert materials and active additives. When consumers hold a silicone bead, its safety stems from the stable structure of silica. However, when handling plastic ornaments, caution should be exercised against the chronic penetration of additives. In today's booming market for silicone beads, a rational understanding of material properties and rigorous selection of certified products are crucial for achieving both aesthetic appeal and health.