What are Japanese plastic bento boxes made of? Are they ...

What are Japanese plastic bento boxes made of? Are they ...

[I've substantially updated this article recently to answer some emailed questions about bento accessories and so on, so here it is again for your reading pleasure. Originally posted in August .]

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I recently received an email from a Just Bento reader concerned about the plastic used to make bento boxes. She was worried since she couldn't read the Japanese writing on the packaging. I'm sure many other readers share similar concerns due to recent media reports about plastics leaching chemicals into food and beverages. Please keep in mind that I am not a scientist or expert, just a concerned consumer like you. Here's what I've been able to find through research on various Japanese and English-language websites.

Bento Boxes from Japanese Manufacturers

The parts of plastic bento boxes that contact food, made by well-known Japanese manufacturers, are generally composed of three types of plastics: polyethylene terephthalate (PET), polypropylene (PP), or a compound of PET and acrylonitrile butadiene styrene (ABS) known as PET-A. A common practice is to use PP or PET-A for the box body and outer lid, while polyethylene is utilized for the flexible inner lids or main lids on small side boxes.

For instance, cheaper bento boxes produced by Nakano Co. (manufactured in China), including popular brands like Puti Fresh, Lube Sheep, and Clickety-Clack sold at Daiso and similar '100-yen' stores, are made of PP. According to The Green Guide, owned and operated by National Geographic, PP is classified as safe, although it isn't very recyclable.

Higher-end plastic bento boxes, such as the extremely popular models by Hakoya (also known as Tatsumiya Shikki) or Yellow Studio (mostly manufactured in Japan, with some accessories produced in China), predominantly use PET or PET-A. Hakoya also employs other plastics for parts of their boxes that do not make direct contact with food. According to The Green Guide, the main objection against PET lies in its porous nature; thus, it isn’t recommended to reuse thin PET water bottles. However, several Japanese reports indicate that PET-A is regarded favorably as a recyclable and food-safe plastic. In practice, I find that my Hakoya and Yellow Studio bento boxes are easier to clean and present a better finish than my Lube Sheep boxes. (Update: As of late 2020, I've stopped using my Lube Sheep boxes—not due to safety concerns, but they tend to look a bit worn out with prolonged use. Well, you can't expect much from boxes that retail for 100-200 yen ($1-2 or so) in Japan.)

What about BPA?

The substance generating the most controversy and concern regarding plastic food containers is bisphenol-A, or BPA. This exists in polycarbonate, a clear plastic used for some water bottles, as liners in metal cans, and other applications. None of the major Japanese bento box manufacturers incorporate polycarbonate into components of their plastic bento boxes or water bottles that contact food. (I have encountered a few thermal mugs that use polycarbonate for the exterior parts that do not touch the liquid.) It's worth mentioning that the Japanese canning industry began voluntarily reducing BPA use as can liners as early as 2001, a decade before BPA sparked discussions in the United States, for example. (see.)

In summary, any bento box from a reputable Japanese maker should be perfectly safe. Food safety regulations in Japan are generally as stringent as those in North America or Europe.

However, you should always adhere to the instructions regarding whether a box is microwave-safe or dishwasher-safe. If in doubt and concerned, consult the seller of your bento box, or simply refrain from microwaving it. It's needless to say, plastic is not suitable for oven or stovetop use!

(Research on the safety of BPA, especially for adults, remains inconclusive. As with any health-related news, try to read as many reputable studies as possible and maintain an open mind.)

Bento Accessories (picks, inner cups, baran, etc.)

Most rigid plastic bento accessories produced by companies like Torune, such as picks, are fabricated from ABS and/or polystyrene. Many reusable inner cups utilize silicone. Flexible plastic items like baran (dividers resembling 'sushi grass') produced by Torune are made from PET.

It is important to note that most of these accessories (except for silicone cups) are not microwave-safe. Therefore, use your cute little picks and similar items for bentos that you don't intend to heat, or remove them beforehand.

Nori cutters made by Arnest (the Niko Niko Punch line) and Kaijirushi (the Chuboos line) consist of ABS (the body) and zinc or a zinc alloy (the cutting parts). I lack information on repurposed cutters meant for use on paper and other non-food products. If you're particularly safety-conscious, you may want to avoid using these cutters on food.

Food cutters made by Arnest, such as the Kyarappa line, are composed of polystyrene.

What Some Popular Non-Japanese Manufacturers Use:

• Rubbermaid: Their website offers a useful page listing which products contain BPA (i.e., are made of polycarbonate) and which do not. (Generally, their clear plastic containers contain BPA.)
• Lock & Lock food containers (unknown regarding their non-food containers): PP
• Fit & Fresh: PP
• IKEA (at least their 365+ line): polypropylene carbonate (PP-C)
• Tupperware (food containers): low-density polyethylene (LDPE) or PP

Plastics to Avoid

It might be tempting to reuse takeout containers. However, according to The Green Guide, that may not be the best idea. Essentially, you should avoid reusing plastic containers that are not designed for multiple uses, like takeout boxes, if you're concerned about plastic safety.

Plastic Alternatives?

The most practical alternative to plastic for bento boxes is likely stainless steel. See Stainless steel bento boxes. My favorite model has a silicone sealing element around the inner rim of the lid; this is acceptable to me as a 'green' bento box, making it very practical. There are also 100% stainless steel bento boxes or lunch boxes, such as those from Lunchbots (their orange-lid model is suitable for a bento box). Be cautious with moist foods, as these lids are not leak-resistant.

Stainless steel bento boxes are generally more expensive than plastic ones, but they should last considerably longer with proper care.

A stylish yet high-maintenance alternative to plastic is wood. Traditionally, bento boxes were made from wood, either untreated or lacquered. Wooden bento boxes are exquisite but require careful handwashing and immediate drying with a soft cloth after cleaning. The renowned Magewappa wooden box, crafted from uncoated bent Japanese cedar, is a beautiful example.

This is my personal opinion, but when it comes to wooden bento boxes, you truly get what you pay for. Avoid cheap wooden options—these typically have rough finishes, poor craftsmanship, and can be quite unpleasant. Anticipate spending at least $40-50 or more for a quality wooden bento box. A genuine Magewappa box will cost at least 6,500 yen (around $70) from reputable stores in Japan. On the plus side, a high-quality wooden bento box will endure for years when taken care of properly.

See Also

(Update added 1/09: All links in this article to The Green Guide site are broken, as they apparently changed them without proper redirects. Worse, their internal search results lead back to the homepage too. As a web developer, I find this very disappointing. However, once you navigate to their site (all links direct to the new homepage), you can browse for relevant information. This page regarding Bisphenol-A (BPA) is current, at least until they alter things again.)

(Update added 2/10: Added link to Rubbermaid BPA page; included information on bento accessories and the plastic alternatives section.)