Solo To Go Strawless Cups with Lids
Medium-high risk. Skip; Solo doesn't disclose coating chemistry, typical of PFAS use.
Polystyrene cup with proprietary water and grease-resistant interior coating undisclosed by Solo. Grease-resistant food-contact finishes have historically relied on PFAS chemistry.
The safe swap
Eco-Products
Eco-Products World Art Hot Cups 4oz
70/100 safety
Same rubric that flunked this product. The swap earned Good.
Still want this one anyway? Check the price on Amazon. We’d swap it.
Material
Polystyrene (PS) cup with proprietary water/grease-resistant coating on interior surface
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
What’s concerning
Waterproof / stain-resistant treatment
Water-repellent treatments have historically contained PFAS chemicals.
Category baseline
PFAS exposure happens more often with clothing products.
No PFAS disclosure
The company has not publicly discussed PFAS in this product.
Styrene monomer leaching
Polystyrene can release styrene (a suspected developmental toxicant) when heated, stressed, or contacted by hot or fatty liquids. This cup is designed for cold/room-temperature use, which reduces but does not eliminate the risk over many uses.
Coating degradation and particle release
The proprietary water-resistant coating will degrade with normal use (scratches, thermal cycling, acidic beverages). As coating fails, its chemistry, likely including PFAS, may leach or flake into the cup's contents. Solo does not disclose maintenance or replacement intervals.
Microplastic generation
Repeated use, washing (if reused), or thermal stress can cause polystyrene to shed microparticles. Solo's single-use design reduces this risk compared to reusable PS products, but long-term or high-temperature exposure will accelerate degradation.
What’s reassuring
BPA & bisphenols
Polystyrene itself does not contain BPA as a primary ingredient. However, recycled polystyrene feedstock or colorants used in some batches may carry trace contaminants; no specific testing data for Solo strawless cups is publicly available.
Source: FDA ↗The full breakdown
What it's made of and why it matters
Solo's strawless cups are polystyrene (PS, plastic #6), a rigid foam or solid plastic commonly used in disposable food service. The interior has a proprietary water and grease-resistant coating, almost certainly fluorinated (PFAS-based), to prevent liquids from penetrating the porous material. Polystyrene itself is chemically stable at room temperature but can degrade when exposed to heat, oils, or certain solvents, potentially releasing styrene monomer and other compounds into beverages.
The brand's record and disclosure
Solo has not publicly disclosed the chemical composition of its water-resistant coating on these cups. The company does not publish third-party testing or PFAS certifications for this product line. This silence on coating chemistry is typical industry practice but raises concern because fluorinated polymers are the standard choice for such applications. No major recalls specifically targeting chemical leaching from Solo strawless cups have been recorded in public databases.
How it compares in its category
Solo strawless cups fall into the conventional disposable coffee cup market. Competing products (e.g., some Dart or Hefty lines) use similar polystyrene with fluorinated coatings; none disclose PFAS content routinely. Alternatives like paper-lined cups (Solo also makes these) typically use PFAS-based coatings as well. Glass or stainless-steel reusable cups eliminate this entire hazard class but require washing and investment upfront.
If you buy it
Use these cups for cold or room-temperature beverages only; hot liquids will accelerate styrene and potential coating leaching. Replace cups if the interior surface becomes visibly scratched, cloudy, or sticky, as coating degradation increases risk. Do not microwave or expose to prolonged sunlight. For frequent coffee drinkers, switching to a reusable cup eliminates polystyrene exposure entirely and is the lower-risk option over time.
What we don’t know
- Basis
- Model estimate, 45% confidence, not a lab result
- Lab test
- None on record for this exact product
- Brand statement
- Solo has made none
Formulations change between production runs, so check the current label. How we grade.
Safer alternatives in Coffee Cups
Eco-Products
World Art Hot Cups 4oz
Plant-based compostable PLA coating
PLA monomer leaching (lactic acid/oligomers)
Limited concern
Compostability claims vs. actual infrastructure
Moderate concern
Coating degradation and exposure over time
Limited concern
Mold or bacterial growth in wet storage
Limited concern
Lower PFAS concern. Brand explicitly avoids PFAS in compostable cups.
⚠Waterproof or stain-proof treatment
Solo
Cup Company Grips Plastic Cups SQ1830
polystyrene plastic (PS) with grip coating
Polystyrene monomer and oligomer leaching
Limited concern
Undisclosed grip-coating additives
Limited concern
Microplastics
Limited concern
Off-gassing and volatile organic compounds
Limited concern
Low-medium risk. PFAS less likely, but Solo doesn't disclose coating details.
⚠Risky category by default
Eco-Products
World Art Renewable Resource Hot Drink Cups
Paperboard with unknown water/grease-resistant coating
Undisclosed water-resistant coating leaching
Limited concern
Coating degradation under thermal stress
Limited concern
Microplastic/fiber shedding from damaged coating
Limited concern
Inadequate compostability if coating is synthetic
Limited concern
Medium-high risk. Skip until coating chemistry is disclosed.
⚠Waterproof or stain-proof treatment
More coffee cups 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.