Cups, Mugs & Thermoses

Cups, Mugs & Thermoses FAQs

• What is the safest material for a travel mug?

  Food-grade stainless steel (18/8 or 18/10) is the safest and most practical material for travel mugs and thermoses. It is chemically stable, does not leach into hot or cold beverages, retains heat effectively, and holds up to daily use and washing. Borosilicate glass is equally safe and completely inert but is less practical for travel due to fragility. The materials to avoid: plastic in any form in contact with hot beverages (including BPA-free plastics, which often contain BPS or other bisphenol substitutes with similar concerns), interior epoxy or non-stick coatings, and enamel coatings of unknown composition that may contain lead. Also pay attention to the lid — many stainless steel travel mugs have plastic lids that contact hot liquid and steam directly. Look for stainless steel or food-grade silicone lids for a fully clean setup.

• Is BPA-free really safe for hot drinks?

  Not necessarily. BPA-free labeling means a product doesn’t contain bisphenol A specifically — but manufacturers typically replace BPA with structurally similar compounds like BPS, BPF, or BPAF that have comparable or worse endocrine-disrupting activity. Research has shown that some BPA-free plastics actually leach more estrogenic chemicals than BPA-containing plastics, particularly when exposed to heat, UV light, or repeated washing. The problem isn’t BPA specifically — it’s the class of bisphenol chemicals and the broader issue of plasticizers leaching into beverages under heat and stress conditions. The only reliable solution is to avoid plastic contact with hot beverages entirely. Stainless steel and borosilicate glass don’t leach — BPA-free plastic still might.

• What is the safest thermos for coffee?

  The safest thermos for coffee is one made from 18/8 or 18/10 food-grade stainless steel throughout — body, interior, and ideally the lid. Stainless steel is chemically inert with coffee and won’t leach metals or chemicals into your beverage under normal use conditions. Avoid thermoses with plastic interior liners, non-stick or powder-coated interior surfaces, or epoxy resin linings — these coatings can degrade with repeated exposure to hot acidic beverages like coffee and may leach chemicals over time. The lid is often the weak point: many premium stainless thermoses have plastic lids with rubber or silicone seals — food-grade silicone seals are fine, but confirm the lid body itself is stainless or food-grade silicone rather than unspecified plastic. Double-walled vacuum insulation is the best construction for heat retention and adds no safety concerns.

• What are the safest cups and mugs for kids?

  For children’s cups and mugs, the safest options are stainless steel with food-grade silicone lids and straws, or borosilicate glass with silicone sleeves for older children. Children have proportionally higher exposure to chemicals from drinkware than adults — smaller body size combined with higher fluid intake relative to body weight means any leaching from cups has greater potential impact. Avoid cups with soft plastic straws, snap-on plastic lids of unknown composition, or interior plastic liners. Even cups marketed specifically for children often contain plasticizers, colorants, and BPA substitutes — "BPA-free" on a children’s cup doesn’t guarantee safety. Food-grade silicone straws are a clean alternative to plastic straws and hold up well to chewing. For sippy cups and toddler cups specifically, all-stainless-steel or stainless-with-silicone constructions are the most thoroughly vetted options available.

• Glass vs. stainless steel mugs — which is better?

  Both are excellent non-toxic choices — the right one depends on your use case. Borosilicate glass is completely inert, flavor-neutral, and the purest option from a materials standpoint. It’s ideal for home use where you want to taste your coffee or tea without any interference from the vessel. The downsides: fragility, no insulation, and not suitable for travel. Food-grade stainless steel (18/8 or 18/10) is the better choice for travel mugs, thermoses, and everyday on-the-go use — durable, insulating, and chemically stable. Some people notice a faint metallic taste with certain stainless mugs, particularly with acidic beverages, though this diminishes with proper seasoning and is not a safety concern. For home use, glass wins on purity and taste neutrality. For travel and durability, stainless steel wins on practicality. Both are far preferable to any form of plastic.

• How can I tell if a mug or travel cup is truly non-toxic?

  Start with materials: the product listing or packaging should clearly state what every part is made from — body, interior, lid, seal, and straw if included. If a brand won’t disclose materials or describes the lid simply as "BPA-free plastic" without specifying the plastic type, that’s a red flag. Look for 18/8 or 18/10 food-grade stainless steel for the body and interior, borosilicate glass for glass products, and food-grade silicone for lids, seals, and straws. Avoid any interior coatings described as non-stick, enamel (unless verified lead-free), or epoxy. Third-party certifications to look for: California Prop 65 compliance (required for products sold in California, sets limits on lead, cadmium, and other toxics), NSF/ANSI 51 (food equipment safety), and FDA food contact compliance. Brands that publish these certifications and disclose full materials are the most trustworthy. When in doubt, stick to products from brands that specialize in non-toxic drinkware and have transparent ingredient and materials policies.