{"operation":"document","citation":"25-0083","title":"EMD Electronics — Hazardous Materials Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2026-01-07","effective_on":null,"summary":"25-0083 response to EMD Electronics concerning 172.101, 173.22.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0083.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0083.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0083","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2026-01/250083.pdf","body":"<<<PAGE 1>>>\n\n1200 New Jersey Avenue, SE\nWashington, DC 20590\nU.S. Department\nof Transportation\nPipeline and Hazardous\nMaterials Safety\nAdministration\nJanuary 7, 2026\nJeanne Enaux\nHead of Product Compliance US\nEMD Electronics\n116 Fairfield Road\nPrinceton, NJ 08540\nReference No. 25-0083\nDear Ms. Enaux:\nThis letter is in response to your June 23, 2025 email requesting clarification of the Hazardous\nMaterials Regulations (HMR; 49 CFR Parts 171-180) applicable to the term “surfactant” with\nrespect to the use of “UN2927, Toxic liquid, corrosive, organic, n.o.s.” for solutions containing\ntetramethylammonium hydroxide (TMAH). You ask whether a surfactant includes all substances\nthat can potentially accelerate dermal uptake, or if the term refers only to substances that have\nhydrophobic-hydrophilic capability.\nFor the purposes of classifying a non-aqueous solution of TMAH, the HMR does not define the\nterm “surfactant.” However, the term generally refers to amphiphilic substances (containing\nboth hydrophobic and hydrophilic parts), which reduce surface tension in liquids, and not the\nsubstances’ potential to accelerate dermal uptake. In accordance with § 173.22 of the HMR, it is\nthe shipper’s responsibility to properly classify a hazardous material. Note that if a mixture\ncontains a substance that can potentially accelerate dermal uptake, the shipper must use the\nclassification criteria of the HMR to classify the mixture and then select a proper shipping name\n(e.g., UN2927, Toxic liquid, corrosive, organic, n.o.s.) in accordance with § 172.101(c)(10).\nI hope this information is helpful. Please contact us if we can be of further assistance.\nSincerely,\nDirk DerKinderen\nChief, Standards Development Branch\nStandards and Rulemaking Division\n\n<<<PAGE 2>>>\n\n25-0083\nCasey\nFrom: Jeanne Enaux <jeanne.enaux@emdgroup.com>\nSent: Monday, June 23, 2025 11:40 AM\nTo: INFOCNTR (PHMSA) <INFOCNTR.INFOCNTR@dot.gov>\nSubject: LETTER OF INTERPRETATION REQUEST\nGood morning,\nWe have an inquiry regarding the DG classification law and would appreciate your assistance\nin clarifying its requirements.\nBeginning of 2025 updated regulations for the transport of dangerous goods (IATA/IMDG) has\nbeen published and the implemented updates include a change in classification for TMAH\n(Tetramethylammonium hydroxide) and its solutions.\nThe recognized toxicity of TMAH is going to be introduced for all existing proper shipping\nnames along with the limitation to aqueous solutions. Additionally, a new proper shipping\nname (UN 3560) for aqueous solutions with >25% TMAH and classification criteria for other\n(non-aqueous) TMAH solutions are going to be introduced.\nWe have a question about the non-aqueous solution. It is mentioned in the text\nOther formulation containing a surfactant > 1% and ≥ 8.75% TMAH à UN2927, toxic\nliquid, corrosive, PG I\nOther formulation containing a surfactant > 1% and > 2.38% - < 8.75% TMAH à\nUN2927, toxic liquid, corrosive, PG II\n\n<<<PAGE 3>>>\n\nWe would like to get a letter of interpretation on the definition of the term “surfactant” in\nUN2927 classification?\n(Is it only substances that have hydrophobic-hydrophilic capability OR all substances that can\npotentially accelerate dermal uptake? Any other way the term should be defined?...)\nThank you in advance for your help\nRegards\nJeanne Enaux\nHead of Product Compliance US\nEmail: Jeanne.enaux@emdgroup.com\nPost mail: 116 Fairfield Road, 08540 Princeton NJ, USA\nTel: +18483130986\nThe Electronics business of Merck KGaA, Darmstadt, Germany operates as EMD Electronics in the U.S. and Canada.\nThis message and any attachment are confidential and may be privileged or otherwise protected from disclosure. If\nyou are not the intended recipient, you must not copy this message or attachment or disclose the contents to any\nother person. If you have received this transmission in error, please notify the sender immediately and delete the\nmessage and any attachment from your system. Merck KGaA, Darmstadt, Germany and any of its subsidiaries do not\naccept liability for any omissions or errors in this message which may arise as a result of E-Mail-transmission or for\ndamages resulting from any unauthorized changes of the content of this message and any attachment thereto. Merck\nKGaA, Darmstadt, Germany and any of its subsidiaries do not guarantee that this message is free of viruses and\ndoes not accept liability for any damages caused by any virus transmitted therewith.\nClick emdgroup.com/disclaimer to access the German, French, Spanish, Portuguese, Turkish, Polish and Slovak\nversions of this disclaimer.\nPlease find our Privacy Statement information by clicking here: emdgroup.com/privacy-statement (U.S.) or\nemdserono.com/privacy-statement (Canada)","truncated":false,"body_characters":4731}