Testing and Standards

Cytotoxic means harmful to living cells. The laboratory takes whatever the fabric releases into sweat, puts it in contact with living cells, and measures whether those cells keep growing normally. It is a first check on skin compatibility, and it gives one overall figure rather than naming individual substances.

Standard

ISO 10993-5:2009

Method Detail

A sweat extract was made from the whole garment by soaking it in acid perspiration solution to ISO 105-E04 for 24 hours at 37°C with light shaking, then adjusted to pH 7.3 to 7.4 and sterile filtered, at a ratio of 0.1 g per ml. L929 mouse fibroblast cells were grown for 68 to 72 hours in four dilutions of that extract, and cell growth was measured by MTT assay at 570 nm against solvent, positive and negative controls. Sample preparation followed ISO 10993-12 and the evaluation was framed by ISO 10993-1.

Sample Tested

One Her Bloom Boyshort, style 29-3 (the Shortie, Heavy Flow), size 4XL, in black. The sweat extract was made from the whole garment.

Laboratory

Hohenstein Laboratories, Bönnigheim, Germany

Report Issued

7 May 2026

Result

Growth inhibition of 13 percent. ISO 10993-5 treats growth inhibition of more than 30 percent against the solvent control as a cell toxic effect, so this result sits well below the threshold. No dose dependent growth inhibition was seen across the four dilutions.

Skin irritation means damage to skin that heals, such as redness or soreness, brought on by contact with a material. The laboratory applies what the fabric releases to a laboratory grown model of human skin and measures how much of that tissue is still alive afterwards. It is a different question from an allergy, which builds up over repeated exposure and is covered by the sensitization test below.

Standard

ISO 10993-23:2021

Method Detail

Two extracts were made from the whole garment following ISO 10993-12, one in 0.9 percent saline and one in sesame oil, each for 24 hours at 37°C with light shaking at a ratio of 0.1 g per ml. Using both a water based and an oil based solvent means substances that dissolve in either one are picked up. Each extract was applied to reconstructed human epidermis, a three dimensional model of human skin, and left for 18 hours. Tissue viability was then measured by MTT reduction at 570 nm against solvent, positive and negative controls. The evaluation was framed by ISO 10993-1.

Sample Tested

One Her Bloom Boyshort, style 29-3 (the Shortie, Heavy Flow), size 4XL, in black. The extracts were made from the whole garment.

Laboratory

Hohenstein Laboratories, Bönnigheim, Germany

Report Issued

26 May 2026

Result

Tissue viability of 104.7 percent with the saline extract and 112.9 percent with the sesame oil extract. ISO 10993-23 treats viability at or below 50 percent with either solvent as potentially irritating, so both results sit well above the threshold. Viability is measured against an untreated control set at 100 percent.

Skin sensitization means becoming allergic to something after more than one exposure, so that contact later on brings on a reaction. The laboratory takes what the fabric releases into sweat, puts it together with human immune cells, and looks for the signal those cells give off when they meet something that can cause an allergy. It is a screening test, and it gives one overall figure rather than naming individual substances.

Standard

OECD Guideline 442E

Method Detail

A sweat extract was made from the whole garment by soaking it in acid perspiration solution to ISO 105-E04 for 24 hours at 37°C with light shaking, then adjusted to pH 7.3 to 7.4 and sterile filtered. U937 human immune cells were grown in that extract for 45 hours. Flow cytometry then measured how strongly those cells expressed the CD86 surface marker, reported as relative fluorescent intensity against a solvent control, a positive control and a negative control. Sample preparation followed ISO 10993-12 and the test was run to the laboratory's accredited method.

Sample Tested

One Her Bloom Boyshort, style 29-3 (the Shortie, Heavy Flow), size 4XL, in black. The sweat extract was made from the whole garment.

Laboratory

Hohenstein Laboratories, Bönnigheim, Germany

Report Issued

7 May 2026

Result

Relative fluorescent intensity below 150 percent. OECD Guideline 442E treats a result of 150 percent or above as potentially sensitizing, so this sits below the threshold. The laboratory recorded that a sensitizing potential was not detected and that the test was passed.

PFAS are a large group of manufactured chemicals used to make fabric repel water and stains. They break down very slowly, which is the reason they are a concern. We asked for them to be measured in every layer, including the leakproof barrier, since a waterproof layer is the part of a period garment most likely to have been treated with them.

Standard

DIN EN 17681-1 and DIN EN 17681-2, against the AFIRM restricted substance list

Method Detail

Each fabric was solvent extracted with alkaline hydrolysis and analyzed by HPLC-MS/MS. Two fluorotelomer iodides were extracted and analyzed separately by GC-MS/MS. The screen covered more than fifty individual PFAS compounds named by CAS number, measured against the limits in the AFIRM restricted substance list used across the apparel industry. The limit of quantitation was 10 µg/kg for most compounds, 20 µg/kg for the fluorotelomer alcohols and 200 µg/kg for the two fluorotelomer iodides.

Sample Tested

Four fabrics, one for each layer of the garment: the body, the gusset, the absorbent layer and the leakproof barrier. All black. Each layer was tested separately.

Laboratory

Hohenstein Laboratories, Hong Kong

Report Issued

28 August 2026

Result

None of the listed compounds were detected in any of the four fabrics. Not detected means the laboratory found nothing above the limits of quantitation stated above using these methods.

Bisphenols are a group of chemicals used in some plastics and coatings, best known as BPA. Bisphenols can be detected where a fabric has been laminated or coated, so the laboratory looked for them in every layer rather than only in the coated one (leakproof barrier).

Standard

DIN EN ISO 11936, against the AFIRM restricted substance list

Method Detail

Each fabric was solvent extracted and analyzed by HPLC-MS/MS, with a modified extraction solvent. The test covered bisphenol A, bisphenol B, bisphenol S and bisphenol F. The limit of quantitation was 0.1 mg/kg. For textiles the AFIRM list sets 10 mg/kg for bisphenol A and 200 mg/kg for each of the other three.

Sample Tested

Four fabrics, one for each layer of the garment: the body, the gusset, the absorbent layer and the leakproof barrier. All black. Each layer was tested separately.

Laboratory

Hohenstein Laboratories, Hong Kong

Report Issued

28 August 2026

Result

None of the four bisphenols were detected in any of the four fabrics, at a limit of quantitation of 0.1 mg/kg.

Wash durability means how well a garment keeps its color, surface and stitching through repeated laundering. The laboratory washed and dried the garments over and over, and three trained observers graded them at intervals against reference scales.

Standard

AATCC TS-008, laundering to AATCC 150

Method Detail

The garments were machine washed cold on a gentle cycle and line dried, then assessed after 10, 20, 30 and 40 cycles. Each load carried 1.8 kg of cotton ballast so the wash behaved like a normal one rather than a nearly empty drum. Three observers graded color change and staining against the AATCC grey scales, where 5 means no change and 1 means severe change, and also checked pilling, fuzzing, seams, fastenings and printed labels.

Sample Tested

Two garments in black, recorded by the laboratory as Boyshort (the Shortie, Medium Flow) and Detachable brief (the Keep it Brief, Brief).

Laboratory

Hohenstein Laboratories, Hong Kong

Report Issued

27 February 2026

Result

After 40 wash cycles, color change graded 4.0 on the main fabric and lining and 4.5 elsewhere, against a requirement of 4.0 or better. Staining onto adjacent fabrics graded 4.5, against a requirement of 3.5 or better. No pilling or fuzzing, and no significant change to seams, fastenings or printed labels. The laboratory concluded that the general appearance of the samples tested was satisfactory.