I. Why Test for Heavy Metals?
Lead: affects the nervous system and hematopoietic system, posing potential hazards to children's intellectual development;
Mercury: rapidly inhibits melanin production (often illegally added to "rapid whitening" products), but may damage kidneys and disrupt the skin barrier;
Arsenic: carcinogenic; long-term accumulation may lead to skin lesions and internal organ damage;
Cadmium: interferes with calcium metabolism, damages bones and kidneys, and is classified as an IARC (International Agency for Research on Cancer) Group 1 carcinogen.
II. Key Heavy Metals for Testing (Core Regulated Elements by Country)
III. Domestic and International Testing Standards (Limit Requirements)
1. China Standard (GB 7916-2013, Safety and Technical Standards for Cosmetics)
Lead: ≤10 mg/kg (≤0.3 mg/kg for infant and children's cosmetics);
Mercury: ≤1 mg/kg (intentional addition prohibited, except for naturally occurring background levels);
Arsenic: ≤2 mg/kg;
Cadmium: ≤5 mg/kg.
2. International Standards
EU (EC 1223/2009): Lead ≤10 mg/kg, Mercury ≤1 mg/kg, Arsenic ≤2 mg/kg, Cadmium ≤5 mg/kg (largely consistent with China);
USA (FDA): No mandatory limits, but mercury addition is prohibited (except for eye-area cosmetics, which allow ≤65 mg/kg of organic mercury preservatives), and lead must be kept "as low as reasonably achievable";
Japan (Pharmaceutical Affairs Law): Lead ≤10 mg/kg, Mercury ≤1 mg/kg, Arsenic ≤2 mg/kg, Cadmium ≤5 mg/kg.
IV. Laboratory Testing Methods (Core Technologies)
1. Sample Pretreatment
Wet digestion: using strong acids such as nitric acid and perchloric acid with heating to decompose samples; suitable for liquid/paste cosmetics;
Microwave digestion: microwave heating with strong acids in sealed vessels; highly efficient with low contamination risk; suitable for various sample types;
Dry ashing: high-temperature incineration of samples to ash, followed by acid dissolution; suitable for solid powders (e.g., mineral foundations).
2. Testing Instruments (Ranked by Sensitivity)
Inductively Coupled Plasma Mass Spectrometry (ICP-MS): highest sensitivity (detectable at ppb level, i.e., parts per billion), capable of simultaneously detecting multiple elements including lead, mercury, arsenic, and cadmium; currently the mainstream method;
Atomic Absorption Spectroscopy (AAS): divided into flame method (suitable for high concentrations) and graphite furnace method (suitable for low concentrations, e.g., lead, cadmium); can only measure one element at a time; lower cost;
Atomic Fluorescence Spectrometry (AFS): high sensitivity for arsenic and mercury; easy to operate; often used as a supplementary method;
UV-Vis Spectrophotometry: measures concentration via colorimetric reaction; lower accuracy; used only for rapid screening.
V. How Can Consumers Avoid Excessive Heavy Metal Risks?
Reject "rapid-result" products: products claiming "7-day whitening" or "rapid spot removal" may contain illegally added mercury (which has a significant short-term melanin-inhibiting effect); exercise heightened vigilance;
Choose authorized channels + registered products: purchase through official channels such as brand websites and authorized counters; domestically sold cosmetics must be registered on the National Medical Products Administration (NMPA) website (where test reports can be verified);
Avoid risky ingredients: ingredients listed as "unspecified mineral extracts" or "substandard pigments" (e.g., colorants with non-compliant index numbers) may conceal heavy metal contamination;
Review test reports: before purchase, request third-party test reports from sellers (focusing on whether lead, mercury, arsenic, and cadmium levels comply with national standards), especially for niche brands and overseas products;
Stricter requirements for infant and children's cosmetics: infants and children have thinner skin and weaker metabolism; look for "cosmetic registration number" + "infant/children" labeling, and avoid products containing mineral powders and complex ingredients.