With the increasing awareness of environmental protection and health, consumers are paying more and more attention to the material safety of daily necessities. From children's tableware to kitchen tools, from medical consumables to electronic product accessories, silicone and plastic are two mainstream materials, and their safety disputes continue. In business promotion, labels such as "food-grade silicone" and "non-toxic plastic" are often confusing, and the sharing of cases of "plastic carcinogenicity" and "silicone allergy" on social media has exacerbated anxiety. So, how to judge from a scientific perspective?
Chemical composition: Silicone structure is stable, and plastic additives are more risky
Silicone: The core component is silicon dioxide (SiO₂), which is connected by silicon-oxygen bonds (Si-O) to form a three-dimensional network structure. This structure gives it extremely strong chemical inertness and almost no reaction with acids, alkalis, and salts. Laboratory simulation tests show that when high-quality silicone comes into contact with common substances such as cooking oil, alcohol, and lemon juice, the exudate content within 24 hours is less than 0.01mg/cm² (far lower than the FDA food contact material standard).
Plastic: With polymer as the main chain, but plasticizers, stabilizers, colorants, etc. need to be added to improve performance. For example:
PVC (polyvinyl chloride) needs to add 20%-40% phthalate plasticizers. Such substances have been proven to have estrogen-like effects and may interfere with the endocrine system;
Bisphenol A (BPA) in polycarbonate (PC) is easily precipitated under high temperature or acidic conditions, and long-term exposure may increase the risk of obesity and diabetes;
Recycled plastics may contain heavy metals (such as lead, cadmium) or polycyclic aromatic hydrocarbons (carcinogens) due to their complex sources.
Research case:
A study in the journal "Environmental Science and Technology" in 2021 showed that 95% of plastic children's toys detected at least one harmful additive;
Silicone medical catheters were tested for 7 days of human implantation, and no migration of silicon molecules was detected (German TÜV certification data).
Temperature resistance: The tolerance limit of silicone is far higher than that of plastic, and the risk of high temperature is lower
Silicone: The temperature resistance range is usually -60℃ to 250℃, and some special silicones can reach above 300℃. Its molecular chain only physically relaxes at high temperatures and will not break or decompose. For example, after a silicone baking mold is used continuously for 100 times in a 250℃ oven, there is no crack on the surface, no odor, and the exudate test is qualified.
Plastic: Temperature resistance varies by type, but is generally lower than silicone:
PP (polypropylene): Temperature resistance of about -20℃ to 120℃, easy to deform and shrink after exceeding;
PS (polystyrene): Temperature resistance of only 0℃ to 70℃, commonly used in disposable lunch boxes, heating will release styrene monomer (classified as a Class 2B carcinogen by the International Agency for Research on Cancer);
Melamine plastic (imitation porcelain tableware): Temperature resistance of about -30℃ to 120℃, overheating may release melamine (toxic dose as low as 50mg/kg).
Experimental comparison:
The silicone spoon is soaked in a 200℃ oil pan for 30 minutes, and the surface temperature only rises to 120℃, without chemical changes;
The plastic spoon softens after being boiled in 100℃ water for 5 minutes, and some edges turn white (low molecular polymers are precipitated).
Biocompatibility: Silicone is widely recognized in the medical field, and plastics need to be strictly screened
Silicone: Due to its extremely low biological reactivity, it is listed as a "generally recognized as safe" (GRAS) material by the FDA and is widely used in medical scenarios:
Artificial heart valves: can work continuously in the body for more than 20 years;
Scar patches: Reduce excessive collagen deposition through the closure of silicone, with an efficiency of over 80%;
Drug sustained release system: Silicone membrane can control the release of hormone drugs, and the blood drug concentration fluctuation is less than 5%.
Plastics: Some types have biosafety disputes:
Polyurethane (PU): used in mattresses and shoe materials, may release isocyanates (irritate the respiratory tract and cause asthma);
Phenolic plastics: used in bakelite tableware, may release formaldehyde (IARC listed as a Class 1 carcinogen) when exposed to acid;
Biodegradable plastics (such as PLA): Although environmentally friendly, the degradation product lactic acid may change the local pH value and cause irritation to sensitive people.
Clinical data:
Ten years after silicone breast implants, the capsular contracture rate is less than 5%;
The plasticizer DEHP (di(2-ethylhexyl) phthalate) in plastic infusion bags may cause liver damage in newborns (European Medicines Agency has restricted its use).
Environmental impact: Silicone degradation cycle is short, plastic pollution lasts for a hundred years
Silicone: Biodegradation can be achieved by adding organic catalysts (such as diatomaceous earth composite silica gel), or decomposed into water and silica under industrial composting conditions. The natural burial degradation cycle is about 50-100 years, and the degradation products are non-toxic.
Plastics:
Traditional plastics (such as PE, PP) take 200-500 years to degrade, and microplastics have penetrated into the human placenta and deep-sea sediments;
Burning plastics produces dioxins (toxicity equivalent to 130 times that of cyanide), and landfilling occupies land resources and pollutes groundwater;
Biodegradable plastics (such as PLA) require specific industrial conditions (above 58°C, high humidity), and degrade slowly in the natural environment.
Ecological research:
Recycling each ton of silicone products can reduce 1.2 tons of CO₂ emissions;
About 8 million tons of plastic flow into the ocean every year, which is equivalent to dumping a garbage truck every minute.
Considering chemical stability, temperature resistance, biocompatibility and environmental impact, high-quality silicone is significantly safer than most plastics, especially suitable for direct contact with food, human body or high temperature environment. However, consumers still need to pay attention to:
Avoid absolute cognition: Plastics are not completely unsafe. For example, PP and PE can be used in storage boxes and water cups at room temperature, but high temperature or acidic environment should be avoided;
Focus on usage scenarios: Although silicone is resistant to high temperature, long-term ultraviolet radiation may cause aging and brittleness; if plastics choose compliant products, they can also meet short-term use needs;
Pay attention to certification standards: Give priority to products certified by FDA, EU 10/2011 (EU Food Contact Materials Regulation) and other certifications to reduce risks.
The core of safe choice lies in "matching needs" and "controlling risks". Whether it is silicone or plastic, understanding its characteristic boundaries can make the material truly serve life, rather than become a health hazard.