PFAS in Waterproof Hiking Socks, Which Brands Grade Best and Worst

Based on available materials and public disclosure data, the clearest pattern in our database is that wool-blend hiking socks from Smartwool, Darn Tough, Bridgedale, Merrell, and The North Face mostly land in the "Good" tier, while the dedicated waterproof membrane socks from Bridgedale's StormSock line and two Merrell Moab waterproof models fall into the "Bad" tier. The split is not about brand reputation, it is about construction. Standard cushioned hiking socks rely on wool and nylon fibers, while fully waterproof socks typically depend on a laminated membrane that has historically used PFAS-based treatments to block water without blocking breathability.

If you want a model-based estimate of lower concern in this category, the Darn Tough Men's Spaced Out Micro Crew Lightweight Hiking Socks and the other "Good" graded socks below are reasonable starting points for further research. None of these gradings are lab certifications. They are our model's estimate from materials disclosure and public data, not a chemical test of the actual sock you'd buy. For a broader look at how clothing fares across categories, see our clothing roundup, and for a wider search across products, try /finder.

Summary comparison table

Product	PFAS Grade (model estimate)	Verdict
Smartwool Mountaineer Classic Edition Max Cushion Crew	Good, 65/100	Lower concern, standard wool-blend construction
Smartwool Hike Full Cushion Crew Socks	Good, 65/100	Lower concern, no waterproof membrane
Smartwool Hike Classic Edition Full Cushion Crew	Good, 65/100	Lower concern, similar profile to sibling models
Darn Tough Spaced Out Micro Crew Lightweight	Good, 65/100	Lower concern, merino wool based
Darn Tough Hiker Encounter 2-Pack	Good, 65/100	Lower concern, classic trail sock build
Darn Tough Weird and Wild Hiking 2-Pack	Good, 65/100	Lower concern, same category construction
Bridgedale Lightweight Boot Socks	Good, 65/100	Lower concern, non-membrane boot sock
Merrell Moab Hiker Low Cut Sock	Good, 65/100	Lower concern, standard trail sock
Merrell Premium Wool Trail Low Cut Sock	Good, 65/100	Lower concern, wool-based build
Merrell Premium Wool Trail Crew Socks	Good, 65/100	Lower concern, wool-based build
The North Face Hiking Crew Socks	Good, 65/100	Lower concern, standard crew sock
Bridgedale StormSock Waterproof Heavyweight Boot Socks	Bad, 20/100	Higher concern, waterproof membrane construction
Bridgedale StormSock Midweight Knee	Bad, 20/100	Higher concern, same membrane family
Merrell Moab Hiker Crew Hiking Socks	Bad, 20/100	Higher concern, waterproof crew construction
Merrell Moab Hiking Quarter Socks	Bad, 20/100	Higher concern, waterproof quarter construction

How we are grading these, and what the grade actually means

Every grade listed here is a model-based estimate built from publicly available materials disclosures, brand marketing language, and category-level patterns, not a laboratory chemical analysis of each specific pair of socks. A "Good" grade (65/100 in our system) means the product shows a lower concern profile based on available materials and data, primarily because it relies on wool, nylon, and elastane rather than a laminated waterproof membrane. A "Bad" grade (20/100) flags higher concern, typically because the product is explicitly marketed as waterproof and that function is commonly achieved in this category using fluoropolymer or fluorocarbon-based membrane treatments. We have not seen third-party lab verification for any specific product in this list confirming the presence or total absence of PFAS. Any association we describe between waterproofing claims and PFAS use is a pattern-level inference, not a certified test result for the individual sock on the shelf.

Why waterproof socks are the PFAS risk zone

Hiking socks that are not explicitly waterproof generally rely on merino wool, synthetic wicking fibers, and simple knit construction. There is no functional need for a fluorochemical coating in a standard cushioned crew sock, which is one reason the wool-dominant products in our table land in the "Good" tier. Waterproof socks are a different category entirely. To stop water from passing through a knit fabric while still letting some vapor escape, manufacturers have historically used membranes similar to those found in waterproof jackets and boots, and those membranes have frequently depended on PFAS chemistry for their water-blocking performance. This is the same dynamic we see across waterproof boots and other waterproof textile categories, so if you are assembling a PFAS-conscious hiking kit, socks are only one piece of the puzzle.

Products graded Good, lower concern

Smartwool Mountaineer Classic Edition Maximum Cushion Crew Socks

Materials, according to brand-stated information, center on merino wool blended with nylon and elastane for cushioning and shape retention. Smartwool markets this sock for cold-weather mountaineering and heavy boot use, not as a waterproof product. Pros include a well-established wool-blend construction and a "Good" model-based grade in our database. A reasonable con is that no brand or third party has published a specific PFAS-free lab certification for this exact SKU, so the "lower concern" label reflects materials-based estimation rather than confirmed absence. View the full profile here.

Smartwool Hike Full Cushion Crew Socks and Hike Classic Edition Full Cushion Crew Socks

Both of these use the same general wool-synthetic blend approach that Smartwool applies across its hiking line, based on available product descriptions. Smartwool's brand claims emphasize moisture management and durability rather than waterproofing, which lines up with their "Good" 65/100 grade. The main pro is consistency across the product family, with multiple SKUs scoring the same in our system. The con, again, is that this is an estimate derived from category and materials patterns, not a verified independent lab test of these exact socks. See Hike Full Cushion Crew and Hike Classic Edition Full Cushion Crew.

Darn Tough Spaced Out Micro Crew, Hiker Encounter 2-Pack, and Weird and Wild Hiking 2-Pack

Darn Tough's hiking line is built primarily from merino wool and nylon, and the brand is known for a lifetime warranty rather than waterproof membrane marketing. All three of these models carry the same "Good" 65/100 estimate in our database. Pros include brand consistency, a non-membrane construction, and strong durability claims from the company. Cons are the same transparency gap seen across this tier, Darn Tough has not published third-party PFAS test results for these specific socks that we are aware of, so "lower concern" remains an estimate rather than a guarantee. Explore Spaced Out Micro Crew Hiker Encounter 2-Pack, and Weird and Wild Hiking 2-Pack.

Bridgedale Lightweight Boot Socks

This is the non-waterproof entry in Bridgedale's lineup, built from a wool-synthetic blend rather than a membrane. It scores "Good" at 65/100, a sharp contrast to Bridgedale's own StormSock line covered below. The pro here is clear differentiation within the same brand, when Bridgedale is not marketing a product as waterproof, the estimated concern level drops. The con is the usual caveat, this is a model estimate based on materials and disclosure patterns, not a chemical assay. See the Lightweight Boot Socks listing.

Merrell Moab Hiker Low Cut Sock, Premium Wool Trail Low Cut Sock, and Premium Wool Trail Crew Socks

These three Merrell products all use conventional wool-blend knits and all land in the "Good" tier at 65/100. Notably, Merrell's non-waterproof Moab and Premium Wool Trail socks score very differently from the brand's waterproof Moab Crew and Moab Quarter socks discussed in the next section, which is one of the clearest single-brand illustrations in this guide of how waterproofing function, not brand identity, drives PFAS concern level. Pros include straightforward wool-based construction and consistent scoring. Cons remain the standard transparency limitation, no specific third-party lab confirmation is cited for these exact products. Review Moab Hiker Low Cut Sock Premium Wool Trail Low Cut Sock, and Premium Wool Trail Crew Socks.

The North Face Hiking Crew Socks

The North Face's hiking crew sock follows the same pattern as the rest of the "Good" tier, using a wool-synthetic knit rather than a waterproof laminate. It carries a 65/100 estimate. The pro is alignment with the broader non-membrane sock category trend toward lower estimated concern. The con is identical to every other product in this tier, this is a materials-based model estimate, not a laboratory result. View The North Face Hiking Crew Socks.

Products graded Bad, higher concern

Bridgedale StormSock Waterproof Heavyweight Boot Socks and StormSock Midweight Knee

Both StormSock products are explicitly marketed by Bridgedale as waterproof, which typically means a membrane layer is laminated into the sock to block water while attempting to preserve some breathability. Both score "Bad" at 20/100 in our model. Brand-stated claims focus on keeping feet dry in wet conditions, which is a real functional benefit for hikers, but that functionality is commonly associated with fluorochemical treatments across the broader waterproof textile industry. We have not seen a published third-party lab test confirming PFAS presence or absence in these specific socks, so the grade reflects category-level and disclosure-based estimation. Pros include genuine waterproofing performance for wet trail conditions. Cons include the elevated estimated concern level and the lack of independent verification either way. StormSock Waterproof Heavyweight Boot Socks and StormSock Midweight Knee carry the full detail.

Merrell Moab Hiker Crew Hiking Socks and Moab Hiking Quarter Socks

These two waterproof Moab socks sit in sharp contrast to the non-waterproof Moab Low Cut sock covered above, despite sharing a brand and product line name. Both score "Bad" at 20/100. Merrell's brand-stated claims emphasize waterproof protection for trail use, again a function historically achieved through membrane technology that has frequently relied on PFAS chemistry across the outdoor industry. Pros include the practical dry-foot benefit hikers are buying these for. Cons include the higher estimated concern grade and the absence of specific third-party testing data confirming either presence or absence of PFAS in these exact products. Moab Hiker Crew Hiking Socks and Moab Hiking Quarter Socks have the full listings.

What to avoid

• Any sock explicitly marketed as "waterproof" without a clear statement of what membrane technology is used and whether it is PFAS-free, based on brand disclosure you can actually find and read.
• Vague marketing phrases like "advanced water repellent technology" with no named chemistry, which in our experience across categories often correlates with older fluorocarbon-based durable water repellent (DWR) treatments.
• Assuming that because a brand makes one PFAS-lower-concern sock, its entire waterproof line follows the same profile. The Merrell and Bridgedale data in this guide shows the opposite can be true within a single brand.
• Treating any grade in this guide, "Good" or "Bad," as a certified lab result. All scores here are model-based estimates from materials and public disclosure, not chemical testing of the specific retail product.

Our pick

Based on available materials and data, the wool-blend hiking socks without waterproof membrane claims are the more reasonable starting point if PFAS exposure is your primary concern, and the Darn Tough Spaced Out Micro Crew Lightweight Hiking Socks and the Smartwool Hike Full Cushion Crew Socks are representative of that lower-concern tier at 65/100 in our model. If you specifically need waterproofing for wet trail conditions, recognize that you are likely trading estimated lower PFAS concern for functional dryness, since the waterproof-specific products in this category, including both Bridgedale StormSock models and the two waterproof Merrell Moab socks, graded "Bad" at 20/100 in our system. No claim here should be read as "PFAS-free" or "safe" in an absolute sense, brand-stated claims and our model estimates are not the same as independent laboratory verification. For a wider view of how clothing and footwear categories compare, visit our clothing category guide or search any product directly at /finder.

Frequently asked questions

Does a Good grade mean a sock is PFAS-free?

No. A "Good" grade of 65/100 in our system reflects a model-based estimate of lower concern, built from publicly available materials disclosures and category patterns, not a laboratory test confirming the total absence of PFAS. Treat it as a reasonable starting point for your own research, not a certification.

Why do waterproof hiking socks score worse than regular hiking socks?

Based on available materials and data, waterproof socks typically rely on a laminated membrane to block water while allowing some breathability, and that membrane technology has historically been associated with fluorochemical treatments across the outdoor textile industry. Non-waterproof socks generally use wool and synthetic knit fibers that do not require this kind of coating, which is reflected in the grade difference shown in our comparison table above.

Is there a proven health risk from wearing PFAS-treated socks?

Research has found associations between certain PFAS compounds and health concerns in some studies, but association is not the same as proven causation for any specific consumer product or individual. Skin contact exposure levels and pathways also differ from the exposure routes studied in most PFAS health research. If you want to reduce potential exposure, choosing lower-concern graded products in categories like waterproof boots or everyday clothing is a reasonable precaution, not a guarantee of any specific health outcome.