Glasslock · Food Storage Containers
Glasslock 6-Piece Square Oven Safe Container Set
Lower PFAS concern; glass food containers pose minimal risk unless lids use treated polymers.
Glasslock containers are primarily borosilicate glass, which is inherently PFAS-free and non-reactive for food storage. The main uncertainty is whether plastic lids contain Teflon-family coating coatings or PFAS-based water/grease repellents, Glasslock does not publicly disclose lid composition or PFAS testing.
Shop Glasslock on Amazon →Material
borosilicate glass with plastic lids
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
Why this grade
Category baseline
food packaging is a category where PFAS exposure is more common.
No PFAS disclosure
No public statement about PFAS in this product.
Uncoated safe material
Bare, uncoated material (cast iron, stainless, carbon steel, or glass) with no surface treatment to contain PFAS.
The full breakdown
What it's made of and why it matters
Glasslock uses borosilicate glass, a material engineered to resist thermal shock and chemical leaching. Borosilicate is fundamentally safer than standard soda-lime glass because its silica backbone is cross-linked with boron oxide, making it chemically inert at typical cooking temperatures (up to 400F for this product). The plastic lids are the material variable: they appear to use polypropylene (PP) or similar, which is stable below 200F but the seal gasket composition is not publicly disclosed by the brand.
The brand's record and disclosure
Glasslock has not published a public PFAS reduction statement or third-party certifications (no NSF, BPA-free badges found in standard product literature). The brand has no documented safety recalls related to this container line in FDA or CPSC databases as of current records. Glasslock maintains basic product safety compliance but does not emphasize transparency beyond regulatory minimums.
How it compares in its category
Borosilicate glass containers outperform silicone, stainless steel with epoxy liners, and plastic-based alternatives because glass does not leach into food. Compared to Pyrex (also borosilicate, better-known brand) or OXO (plastic hybrid), Glasslock is competitively priced and functionally equivalent; the main trade-off is brand transparency rather than material safety. Plastic lid quality is the differentiator across all glass container brands, and Glasslock's lids are standard-grade without advanced polymer treatment.
If you buy it
Hand wash lids and do not microwave them; the gasket can degrade or off-gas if exposed to sustained heat above 160F. Inspect the plastic rim and seal annually for discoloration, brittleness, or mold growth in the seal groove. Do not use containers on a direct flame or stovetop; oven use is safe to the stated 400F limit. Replace lids if gaskets crack or residue staining appears, as degraded seals compromise both food freshness and chemical integrity of the storage system.
Beyond PFAS: other things we checked
Established hazard classes for this product type, assessed from public information. These never change the PFAS grade; a Likely flag caps the Verdict at “Buy with care.”
BPA/BPS and endocrine-active plasticizers in lids
Lid material composition is not disclosed by Glasslock. Polypropylene itself is BPA-free, but the gasket seal often uses elastomers or copolymers that may contain BPA, BPS, or phthalate plasticizers. Risk is low if lids are kept below 140F and not microwaved, but repeated hot water washing increases leaching probability.
Microplastics from plastic lid degradation
Polypropylene lids degrade over 2-3 years of thermal cycling and detergent exposure. Microscopic fragments may shed into stored foods, especially acidic or fatty foods that accelerate polymer breakdown. This is a time-dependent hazard, not an immediate one.
Seal gasket mold and bacterial colonization
The silicone or rubber gasket groove is a known micro-environment for mold growth if not completely dried after washing. Glasslock users have reported visible mold in seal areas after refrigerator storage; this is a maintenance issue, not a manufacturing defect, but requires vigilant cleaning.
Borosilicate glass thermal shock and breakage
Borosilicate glass is engineered to resist thermal stress, and Glasslock containers have no documented breakage recalls. However, rapid temperature changes (e.g., cold fridge to 400F oven) can still cause fracture if containers have micro-flaws. Risk is low but not zero.
Lid seal failure and food freshness compromise
Glasslock's clip-lock system is mechanical, not airtight-sealed. Over time, clips weaken or gaskets compress, reducing seal integrity. This does not pose a chemical safety risk but undermines the product's primary function and may lead to mold or bacterial growth in stored foods.
What we don’t know
This grade is a model-based estimate from public materials, coatings, and brand disclosure at 82% confidence. It is not a lab result.
No independent PFAS lab test is on record for this exact product. A lab test could move the score in either direction.
The brand has not made a specific, verifiable PFAS-free statement, so part of this score reflects that missing disclosure rather than a confirmed material.
Formulations and coatings change between production runs. Always check the current label before buying.
Safer alternatives in Food Storage Containers
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⚠Risky category by default
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⚠Risky category by default
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Cream 6.6-Cup Non-Stick Glass Food Storage Container with Lid
borosilicate glass with non-PFAS lid
Lower PFAS concern, glass container with stated non-PFAS lid, though third-party verification absent.
⚠Risky category by default
More food storage containers grades
How we score: every product runs through the same public 0–100 rubric based on materials, coatings, brand disclosure, lab findings, and recalls. See the full methodology → Spotted a mistake? Report an error.