Pyrex No-Leak Glass · Food Storage Containers
Pyrex Freshlock 4 Cup Round Food Storage Container
Lower PFAS concern, glass containers rarely require fluorochemical treatments.
Pyrex Freshlock's primary container is borosilicate glass, which does not require PFAS coatings for food contact. The polypropylene plastic lid may carry minimal PFAS risk but is not a known vector for intentional fluorochemical treatment.
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borosilicate glass with plastic (polypropylene) lid
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
The container body is borosilicate glass, a durable, chemically inert material that does not leach into food under normal use or heating. The lid is polypropylene (PP, #5 plastic), which is generally stable and does not contain BPA or phthalates by standard formulation. Borosilicate glass is specifically engineered for thermal shock resistance, making it safer than soda-lime glass for temperature changes. The glass-to-plastic interface (seal/gasket) is the most sensitive point; gaskets can degrade over time with repeated heating cycles and aggressive dishwasher use.
The brand's record and disclosure
Pyrex (now owned by Instant Brands) has a long history in glass cookware and food storage with no major recalls or hazard disclosures related to the container body itself. The brand does not publicly disclose PFAS testing or commitment to PFAS-free formulations for lids and gaskets. Pyrex maintains certification under standard FDA food-contact material guidelines. No established controversies regarding heavy metal contamination or chemical leaching have been documented for their glass containers in recent years.
How it compares in its category
Borosilicate glass containers (Pyrex, Anchor Hocking, OXO) are the safest option in the glass food storage category because the material itself does not leach. Plastic-only containers (polypropylene or polycarbonate) carry higher risk of migration, especially if heated or stored with fatty/acidic foods. Pyrex's polypropylene lids are comparable to most competitors in thermal stability; however, some brands (e.g., Anchor Hocking Brilliance) offer silicone seals which may have longer lifespans. The Freshlock line is mid-range in durability and does not command premium pricing for exceptional seal engineering.
If you buy it
Do not heat the plastic lid on the stovetop or under a broiler; remove it before microwaving or oven use above 350F (the lid is rated to approximately 212F/100C). Hand-wash the lid and gasket rather than subjecting them to high dishwasher heat to extend seal lifespan; if the seal cracks, discolors, or no longer prevents leaks, replace the lid assembly. Store acidic foods (tomato sauce, citrus) in glass, not plastic lids, to minimize any potential plasticizer exposure. Inspect the gasket annually for cracks or shrinkage; if visible degradation appears, the seal should be replaced to avoid moisture entering the container or food contact with aged rubber.
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.”
Polypropylene lid degradation and migration
Polypropylene is stable under normal conditions, but repeated heating (dishwasher cycles, microwaving with lid on) can cause micro-cracking and potential migration of additives. Pyrex does not disclose additive packages for lids publicly.
Gasket material degradation
User reports exist of Pyrex Freshlock gaskets becoming loose, discolored, or failing to seal after 1-3 years of use. Exact gasket composition is not disclosed; if rubber-based, it may contain vulcanization byproducts that leach slightly when degraded.
Borosilicate glass chip or fracture hazard
While borosilicate glass is more impact-resistant than standard glass, thermal shock (moving from freezer to hot oven) or dropping can still cause cracks. Chipped edges create cutting hazard and may harbor bacteria if not discarded immediately.
Lid-to-glass interface mold or bacterial growth
The seal between lid and gasket can trap moisture if not dried thoroughly after washing. Inadequate air drying or dishwasher storage with wet gasket may promote mold or mildew, especially in humid climates.
Heavy metals in glass formulation
Borosilicate glass used in Pyrex containers has no documented history of lead, cadmium, or arsenic contamination in independent testing. FDA standards for borosilicate food-contact glass are stringent and enforced.
What we don’t know
This grade is a model-based estimate from public materials, coatings, and brand disclosure at 88% 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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Lower concern; glass + plastic lids with stated PFAS-free position, but no third-party verification of lid material.
⚠Risky category by default
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Home 9-Piece Mini Food Storage Set
Borosilicate glass containers with plastic lids
Lower-concern option; glass containers avoid PFAS coatings, but verify lid material before purchase.
⚠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.