Zojirushi Ms. Bento Stainless Lunch Jar
Lower concern. Stainless steel container with standard plastic closures.
Ms. Bento lunch jars are primarily stainless steel with polypropylene seals, inherently lower PFAS risk materials. No PFAS disclosure or special coatings reported. Typical food-contact product with standard manufacturing.
We flunk more products than we pass. This one earned its grade. How we grade
Material
Stainless steel body, polypropylene seals/lids
Lab data
No public lab test
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What Zojirushi Ms. Bento Stainless Lunch Jar is made of, ingredients and materials
The Ms. Bento's main container is stainless steel, which is chemically inert and does not leach metals or compounds into food under normal use. The seals and lids are polypropylene (PP, #5 plastic), a food-grade polymer with low migration risk at room temperature. Stainless steel avoids the concerns that plague ceramic-glazed or aluminum-core containers, where lead, cadmium, or aluminum ions can transfer into acidic or salty foods.
What’s concerning
Category baseline
The starting point for this type of product, before anything specific to this product is counted.
No PFAS disclosure
No public statement from the brand about PFAS in this product.
Polypropylene seal degradation under heat
PP seals and gaskets can soften, warp, or degrade if exposed to temperatures above 70C repeatedly (e.g., boiling water for cleaning or steam). Degradation may increase migration of non-intentional additives, though acute risk is low at normal meal temperatures.
Microplastic generation from seal wear
Repeated opening/closing and UV exposure can cause microscopic wear particles to shed from polypropylene seals into food, especially if seals are damaged or become brittle. Risk is minimized by proper care and timely replacement of worn components.
What’s reassuring
Bare uncoated material
Recorded as a bare, uncoated material with no surface coating or treatment.
BPA & bisphenols
Polypropylene does not require bisphenol A (BPA) or bisphenol S (BPS) in its formulation and is not a known source of these chemicals. Food-grade PP used in Zojirushi products is unlikely to contain these plasticizers, but manufacturer does not publish detailed material specifications.
Source, FDA ↗Lead
Food-grade stainless steel (typically 304 or 316) does not leach lead or cadmium under normal storage or use. No recalled batches of Zojirushi stainless containers with heavy-metal issues have been documented.
Source, ATSDR ↗Phthalates
Polypropylene seals do not require phthalate plasticizers for flexibility; food-contact polypropylene is subject to FDA limits on phthalates even if present as residual contaminants. Zojirushi maintains no published phthalate statement, but the material class presents low risk.
Source, ATSDR ↗How is this PFAS grade calculated?
The brand's record and disclosure
Zojirushi is a Japanese manufacturer with decades of market presence in food storage and thermal containers. The company maintains no published PFAS stance or third-party chemical certifications (e.g., FDA, NSF), but has not faced documented product recalls or safety violations related to chemical hazards in food-contact materials. Their silence on PFAS does not indicate use; stainless steel containers rarely require PFAS for performance.
How it compares in its category
Stainless steel lunch containers have lower concern in the food-storage category because they avoid polymer-leaching and ceramic-glaze hazards associated with other materials. Most competitors use either plastic bodies (higher chemical migration risk), ceramic liners (lead/cadmium glaze risk), or aluminum cores (leaching under acidic conditions). The Ms. Bento's design, stainless exterior with PP seals, represents a lower-hazard choice for daily food transport.
If you buy it
Do not microwave or expose the plastic seals to boiling water; temperatures above 70 degrees Celsius (158 F) can degrade polypropylene and increase migration of residual oligomers. Wash lids and gaskets by hand in warm (not hot) soapy water, and inspect seals annually for cracks or cloudiness, replacing if damaged. Keep the container out of direct sunlight for extended periods, as UV exposure can embrittle plastic closures over time. The stainless steel body itself requires no special maintenance beyond normal washing.
What is not known about PFAS in this product?
- Basis
- Model estimate, 82% confidence, not a lab result
- Lab test
- None on record for this exact product
- Brand statement
- Zojirushi has made a specific claim
Formulations change between production runs, so check the current label. How we grade.
What are the PFAS-free alternatives to Zojirushi Ms. Bento Stainless Lunch Jar?
Klean Kanteen
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- Stainless steel body, silicone gasket lid seal
- The brand calls it PFAS-free, which we have not verified
- Silicone gasket degradation
3 hazards checked on this product, all on its full breakdown.
More lunch boxes 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.