SLES vs SLS vs LABSA: choosing an anionic surfactant

The answer, up front

LABSA, SLES and SLS are all anionic surfactants, but they are not alternatives to each other in any sense a purchase order can treat as equivalent. Three differences govern, and all three are commercial before they are technical.

1. LABSA is a free sulphonic acid. Linear alkylbenzene sulphonic acid is corrosive and is consigned as a Class 8 dangerous good. It becomes a surfactant only when it is neutralised with a base, and that step brings its own hazards, its own base to buy, and water and sodium salts into your formulation. SLES and SLS arrive already neutralised, as sodium salts.
2. Active matter as sold differs by a factor of three or more. SLS needles are around 90–99% active; SLES paste is around 70%; SLES liquid is around 25–28%; LABSA is 85% or 95% depending on the Indian type. A price per kilogram of material is not a price, and a weight-for-weight substitution is not a substitution.
3. The chains the molecules are built from are different, so the price drivers are different. LABSA comes from linear alkylbenzene, a petrochemical. SLES and SLS come from lauryl alcohol, which is made both from the lauric oils — coconut and palm kernel — and petrochemically, by routes that build the chain up from ethylene. So the cost of SLES and SLS can sit on an edible-oil chain, on a petrochemical one, or on both at once depending on the producer’s route. Do not assume the lauric-oil price is the whole story, and do not assume it is irrelevant.

Everything else in this article is downstream of those three facts. Compare on a 100% active basis, read the certificate rather than the trade percentage, and treat LABSA as a chemical reaction you are buying rather than an ingredient.

This is a buyer’s and formulator’s reading guide, not a formulation and not a procedure. It publishes no neutralisation procedure: no quantity, no order of addition and no set-point for your plant — see the section on neutralisation for why. Where it reports a figure from a published process, it says whose process and what the figure was for. Velora is a bulk supplier and trader sourcing from qualified manufacturers, not a manufacturer, and nothing here states or implies that Velora holds any licence or registration.

What the three actually are

LABSA — linear alkylbenzene sulphonic acid, trade name acid slurry

Linear alkylbenzene is sulphonated to give a brown viscous acid. It is the detergency workhorse of the Indian market and it is what most detergent powder and cake is built on, but it is an acid, and the surfactant is its sodium salt. One producer’s technical data sheet for 96% material gives CAS 68584-22-5, a molar mass in the region of 316–326 g/mol, a melting point around 10 °C, and a neutralisation value of 175–188 mg KOH/g. That last figure repays five minutes with a calculator, because what it measures is not stated. Taken on the material as sold, one gram of 96% material at a molar mass of 322 is about 0.00298 mol of monobasic acid, needing roughly 167 mg KOH — below most of the published range, which would mean the balance is other acidity, most obviously the free sulphuric acid, which is dibasic and would contribute something like 23 mg KOH/g at 2%. But 167 plus 23 is about 190, which overshoots the top of the range, so a lot sitting inside 175 to 188 would carry something closer to 0.6 to 1.8% free acid on that reading. And taken on a 100% active basis instead, the sulphonic acid on its own gives about 174 to 178 mg KOH/g across the quoted molar mass range — which lands inside the published band and needs no free acid to explain it at all.

Both readings are arithmetically fine, and the data sheet does not say which basis it is quoting. That is the point worth taking away: a single published range can be a measure of the surfactant or a measure of total acidity depending on a convention nobody wrote down, and either way it is a range. Which is already the first argument against doing this from a textbook equation rather than from an assay of the lot in front of you.

The Indian standard is IS 8401:1994, Alkyl Benzene Sulphonic Acid (Acid Slurry), First Revision — the standard most relevant to anyone trading this material, and the one most often missing from a specification. It defines two types: Type 1 at not less than 95.0% active matter and Type 2 at not less than 85.0%, with free alkyl benzene capped at 2.0% for both and free sulphuric acid capped at 2.0% for Type 1 but 9.0% for Type 2. Hold on to that free-acid difference: it reappears in the caustic requirement and, possibly, in the UN number.

One identity point that matters when you read a safety document. Commercial LABSA under CAS 68584-22-5 is a mixture of homologues, benzenesulphonic acid C10–16-alkyl derivatives, not a single compound. The ILO international chemical safety card most often cited for it, and quoted later in this article, is for dodecylbenzenesulfonic acid — the single C12 compound. The hazards transfer, which is why we use it; the identity is not the same. The card is for CAS 27176-87-0, dodecylbenzenesulfonic acid with the position of the alkyl attachment unspecified, so it is itself an isomer mixture rather than one molecule. And neither that card nor either CAS number tells you anything about the free sulphuric acid in the lot you bought.

SLES — sodium lauryl ether sulphate, INCI sodium laureth sulphate

Lauryl alcohol is ethoxylated — reacted with ethylene oxide — and then sulphated and neutralised. The number of ethylene oxide units is a real product variable, not a detail. One major producer’s standard range lists separate grades at 1 EO, 2 EO and 3 EO in paste form, all around 68–73% active, and liquid grades at 2 EO around 25–28% active. The 2 EO paste is the common article of trade; its data sheet gives CAS 68891-38-3 and describes a flowable paste derived from natural fatty alcohols, supplied unpreserved.

There is an Indian standard, but it is a cosmetics standard rather than a detergent one: IS 11487:1985, Sodium Lauryl Ether Sulphate (SLES) for Cosmetic Industry, written around a 30% solution, with minimum active detergent 27%, cloud point below 0 °C, pH of a 5% solution between 6.0 and 11.0 as amended, and an average ethoxylation of about 2 to 2.5 units on a predominantly C₁₂ chain from coconut or palm kernel. It also carries the 1,4-dioxane limit discussed below.

SLS — sodium lauryl sulphate, also sodium dodecyl sulphate

The same lauryl alcohol, sulphated and neutralised without the ethoxylation step. It is sold as needles, powder or granules at high active matter, and also as a roughly 28–30% liquid. IS 3986:1988, Sodium Lauryl Sulphate for Cosmetic Industry, Third Revision, defines three types — two solid and one liquid — at minimum SLS content of 94.0%, 85.0% and 30.0% respectively, with limits on unsulphated fatty alcohols, sodium sulphate, sodium chloride, arsenic and heavy metals, and pH of a 1% solution between 7.5 and 10.5 for the solid types. Producer literature for high-active solids sits in the same region, at 90% to 99% depending on grade.

If you buy SLS as needles or powder, the handling hazard is dust, and it is the exposure most likely to reach someone in a small plant. The ILO international chemical safety card gives harmful if swallowed or in contact with skin, skin and eye irritation, possible respiratory irritation, and records that airborne particles can reach harmful concentrations when the material is dispersed, especially as powder, and that repeated or prolonged skin contact may cause dermatitis; the reagent-grade safety data sheets we read go further on eyes, to serious eye damage, and add harmful if inhaled. So the controls that matter are at the bag tipping, sieving and transfer points — contain the dust rather than manage the symptoms, and protect eyes against airborne needles. On fire: the card records that it is combustible and decomposes on burning to toxic and corrosive gases the reagent-grade suppliers whose sheets we read classify the solid as a flammable solid for transport. We found no dust explosion class or ignition-energy data for sodium lauryl sulphate, so we do not characterise it as an explosible dust and nor should anyone else without a test on the actual grade. Work from the safety data sheet for the grade you buy, and get a competent person to advise on the dust controls.

SLS is also the one of the three with a life outside detergents. It is a pharmacopoeial excipient with a harmonised monograph: the USP–NF standard, with USP as coordinating pharmacopoeia, became official on 1 May 2021, and requires not less than 85.0% of sodium alkyl sulphates calculated as sodium lauryl sulphate. A European Medicines Agency report on the same excipient cites a matching 85% figure from the European Pharmacopoeia. It is also a permitted direct food additive in the United States under 21 CFR 172.822. None of which means a technical-grade consignment meets any of those monographs — a grade name is not a monograph, which is the whole subject of a separate article in this series.

The commercial point: everything has to be on a 100% active basis

This is the section worth reading twice, because it is where money is lost quietly. The three materials are sold at active matters that differ by a factor of three or more, and the trade descriptions do not line up with the Indian grades.

Read the second column as a purchasing instruction. At 28% active, roughly seventy-two parts in every hundred are not surfactant — mostly water, but with salt and unsulphated organic matter in there too, which the Indian cosmetic-grade standard permits at up to 3.5% and 2.5% respectively in a 30% solution. You pay freight on all of it, and the salt is not inert: it is what controls the viscosity. Swapping SLES 70 for SLES 28 kilogram for kilogram removes about three-fifths of the surfactant from the batch. Comparing a LABSA offer at 85% against one at 95% on rupees per kilogram of material rather than per kilogram of active compares the wrong thing. None of this is subtle; it is simply not usually written down.

SLES 70 and SLES 28 are not two points on a continuum

There is a physical reason the two standard grades sit where they do, and it is in the producer’s own data sheet. Ether sulphate solutions form gel structures on dilution: viscosity climbs steeply at first, then falls away sharply once active substance drops below about 30%. Stable liquid solutions form up to about 28% active, and above that the material goes pasty.

That is why the two common articles of trade are a paste and a dilute liquid rather than a continuous range of strengths — though products do exist at intermediate concentrations, made pourable with hydrotropes or other additions, so this is a reason the simple grades cluster rather than a law about what is possible. A formulator who buys the paste and dilutes it in-house to 28% does not get SLES 28 at a better landed price — they get a different rheology, arrived at through a viscosity peak, in a vessel that has to handle it. The same data sheet makes the related point about salt thickening: sodium chloride should be added as a saturated aqueous solution rather than as a solid. Whether in-house dilution is worth doing is a real question with a real answer, and the answer belongs to whoever runs the mixing plant — not to a landed-cost spreadsheet that treats active matter as linear.

The Indian standards, and the editions, because this is where pages go stale

Most Indian material on this subject cites the right standard numbers with the wrong years, which is the more damaging error because it looks authoritative. These are the editions we could verify as current from BIS’s own records at the date of this article.

Two cautions, and they apply to us as much as to anyone. We verified these edition designations from BIS records, and we read the texts of IS 8401:1994, IS 3986:1988 and IS 11487 (the last two from scanned or mirrored copies rather than official BIS PDFs). We have not read IS 4955:2020, IS 285:2021, IS 2887:2017, IS 13498:2017 or IS 286:2018, so no value or clause in this article is attributed to them. Separately, a second revision of IS 8401 was reported to have gone out for public comment during 2026; we could not confirm that from BIS, whose record still shows the 1994 edition with no superseding standard. Read the current text before writing any of this into a contract. One oddity worth knowing if you order the standard: the copy we read is titled First Revision on its cover while a 2008 amendment sheet styles it Second Revision. That is an inconsistency in the document itself, not a second standard, and either designation refers to the 1994 edition.

What “LABSA 90%” does and does not tell you

IS 8401 has two types and both are minima, not bands: Type 1 at not less than 95.0% active matter, Type 2 at not less than 85.0%. There is no 90% type. So a 90% slurry rules Type 1 out, and on active matter alone it is consistent with Type 2 — which is the useful reading, and it is not what either party usually has in mind when the invoice says 90%.

What the trade percentage does not tell you is the free sulphuric acid, and that is the parameter that matters. Type 2 permits up to 9.0% of it against 2.0% for Type 1, and free sulphuric acid drives the caustic requirement and may drive the transport classification. Nor does it tell you the free alkyl benzene. So ask for the IS type and the certificate of analysis rather than the trade percentage, and where the trade grade does not correspond to the type you want, specify the active matter and the free acid as numbers.

The same reading applies to SLS, where the familiar 90 to 95% spans IS 3986 Type 1 at not less than 94% and Type 2 at not less than 85%: 95% meets Type 1, 90% meets Type 2 on active matter, and the number alone does not say which type was intended. The liquid is where a minimum actually bites: IS 3986 Type 3 requires not less than 30.0%, so a liquid offered at 28% does not meet Type 3, however reasonable the material — and in that case naming the type specifies something the goods cannot deliver.

A live regulatory item: the Quality Control Order on LAB

This is a LABSA story even though LABSA is not the subject of it. The Linear Alkyl Benzene (Quality Control) Order, 2022 was notified as S.O. 1648(E) of 5 April 2022 by the Department of Chemicals and Petrochemicals, under section 16 read with section 25(3) of the BIS Act, 2016, and brings LAB — the feedstock from which LABSA is made — under compulsory conformity to IS 12795:2020.

Conformity under that Order has been suspended, and it has been suspended three times over. As we read the Department’s own notifications index: S.O. 1655(E) of 30 March 2026 suspended it from 1 April 2026 to 1 July 2026; S.O. 3456(E) of 25 June 2026 suspended it for 1 July to 30 September 2026; and S.O. 5343(E) of 29 September 2026 substitutes a single restated window running from 1 April 2026 to 31 December 2026 — which is also the implementation date BIS carries against IS 12795:2020 in its own register of notified Quality Control Orders. The reason given is the avoidance of supply-chain disruption. As at the date of this article we found no later notification.

That it has been extended twice already is the commercially important part, and it cuts in both directions: a requirement deferred three times may be deferred again, and it may equally be allowed to come into force on the stated date. It is a planning assumption, not a fact about 2027.

This item has a date on it and the current window closes at the end of December 2026. Anyone relying on it — for an import, a domestic purchase or a tender — should read the Department of Chemicals and Petrochemicals notifications page on the day rather than rely on this page, and should take the position from the gazette notification rather than from trade-press summaries, which have not always reconciled the dates. Two further points. We looked for a Quality Control Order covering LABSA, SLES, SLS, soaps or synthetic detergents and did not find one; that is the result of our search rather than a statement that none exists. And caustic soda, the base most often used to neutralise LABSA, is the subject of a Quality Control Order of its own — on the same Department’s list against IS 252:2013, notified in April 2018 — so if you are buying the base as well as the acid, check its position for the grade you buy. Read that list with the same caution as everything else here: it still carries entries for chemicals whose Orders have since been rescinded, so appearing on it is not by itself proof that an Order is in force.

Hard water: the one performance difference we could source properly

Comparative foam and detergency data for these three, measured head to head, is not something we were able to verify from a primary source, and this article does not publish a performance rating table for that reason. One performance difference is genuinely demonstrated, and it happens to be the one that drives formulation cost: calcium tolerance.

A 1996 study in Water Environment Research tested ethoxylated alkyl sulphates against calcium directly, across zero, one, two, three and four ethylene oxide units. The non-ethoxylated material — sodium dodecyl sulphate, that is SLS — precipitated visibly, forming a white floc. The one-unit ethoxylate gave a very fine precipitate over part of the range. The three- and four-unit materials did not precipitate anywhere in the calcium range tested, up to 0.1 M. The mechanism is that the ethylene oxide units keep the calcium salt in solution.

The two-unit result — which is the grade most people actually buy — is the equivocal one, and it would be dishonest to leave it out. The paper’s own figure puts a precipitation boundary for the two-unit material at the upper edge of the region tested, while its abstract reports no significant precipitation at two or more ethoxylate units. Read that as the two-unit material being substantially better than the non-ethoxylated one and not as good as the three-unit one, with a boundary somewhere near the top of the calcium range tested — which is a reason to state the ethoxylation degree in the purchase order, not a number to formulate against.

So the practical consequence is a builder consequence. In hard water, a surfactant that precipitates with calcium is lost to the wash and shows up as scum, which is a large part of why detergent powders carry builders and sequestrants at all. Choosing between a sulphate and an ether sulphate can change the builder requirement, not just the surfactant line in the formula.

Scope, honestly stated: that study tested calcium and not magnesium, and its application context was groundwater remediation rather than laundry. The mechanism transfers; the concentrations are not wash-liquor concentrations. We did not find comparable calcium-tolerance data for LABSA or its sodium salt, so this article makes no claim about where LAS sits on that scale.

Mildness: what the evidence actually supports, and what it does not

“SLES is milder than SLS” is the most repeated claim in this subject and it is directionally supportable — on eyes, by a one-category regulatory difference, and nowhere else that we could verify.

Two Australian government hazard assessments of the two groups, both dated 28 June 2013, reach different eye conclusions. The lauryl sulphate group is assessed as serious eye damage, Category 1, H318, on the basis that a 25% solution produced effects in rabbits that were not reversible within 21 days. The laureth sulphate group is assessed one category less severe: serious eye irritation, Category 2A, H319. For skin, both are Category 2, H315 — there is no classification difference, and the laureth assessment itself records severe irritation in some studies at 15 to 30%. Neither is assessed as a skin sensitiser.

Three things follow, and the third is the commercially useful one. First, “mild” is the wrong word for either: both are classified skin and eye irritants and both are concentration-dependent, with rinse-off exposure far lower than leave-on. Second, there is no defensible mildness ratio — we could not obtain the head-to-head human study that most writing on this subject cites, so this article does not rely on it and nor should a specification. Third, and this is where procurement meets formulation: part of the mildness gap people observe in practice is a dilution gap. SLS needles are 90% active and up; SLES 70 is around 70%, so roughly three-quarters of that; SLES 28 is around 28%, so roughly a third of it. A comparison at equal as-supplied weight is a comparison at unequal active, and the irritation data are concentration-banded. The gap is real at 28% and much smaller at 70%, which is a reason to say which grade you mean rather than to argue about the molecules.

There is also a reputational artefact worth knowing about. SLS is the cosmetic and dermatological industry’s standard reference irritant — the European Medicines Agency’s report on it as a pharmaceutical excipient records that it is used as a standard irritating agent and has become the standard reagent for experimental patch testing, with slight to moderate irritation reported in the 0.5 to 10% band and corrosion between 10 and 30% — and, under occluded patches in animal studies, at doses as low as 0.1%. The floor is lower than the headline bands suggest, and occlusion is what moves it. A molecule chosen deliberately to provoke irritation in a test acquires a reputation out of proportion to its behaviour in a product that is on the skin for thirty seconds.

The cancer claim, since it will come up

SLS is not classified as a carcinogen by any authority we could find, and the claim that it causes cancer has no authoritative support. A 2017 Canadian government screening assessment of the alkyl sulphates found no evidence of carcinogenicity or genotoxicity and concluded the group does not meet any of the criteria in section 64 of the Canadian Environmental Protection Act. The 2013 Australian assessment recommends no carcinogenicity classification and finds the material not genotoxic. The European Medicines Agency reports negative bacterial and mouse lymphoma mutation tests and no clastogenic effect in vivo. The ILO international chemical safety card lists no carcinogenicity hazard, which is a reading of an absence rather than a positive finding. Separately, and it is a permission rather than an assessment: in the United States SLS is a permitted direct food additive.

The honest form of that statement matters, though. The same European report records that no conventional lifetime rodent carcinogenicity study has been performed on SLS. So the defensible claim is that there is no evidence of carcinogenicity and no authority lists it as a carcinogen — not that it has been proved not to cause cancer. Nor is it banned: the United States regulator’s list of prohibited and restricted cosmetic ingredients contains no sulphate surfactant, and SLS has a current pharmacopoeial monograph and an Indian Standard reaffirmed in August 2024.

1,4-dioxane: an ethoxylation question, so an SLES question

1,4-dioxane is a solvent in its own right, but in a surfactant it is nobody’s ingredient: it is a trace by-product of ethoxylation. The United States food and drug regulator identifies the ingredients that can carry it by their naming markers — PEG, polyethylene, polyethylene glycol, polyoxyethylene, and the syllables eth and oxynol — and has recommended vacuum stripping to reduce it since the 1980s.

Apply that to our three and the answer falls out of the name. Sodium laureth sulphate carries the marker; sodium lauryl sulphate does not; and LABSA has no ethoxylate in it at all. Reasoning from the naming rule and the structures, SLES is the one of the three with an ethoxylation route to 1,4-dioxane — which is also why the Indian SLES standard carries a 1,4-dioxane limit while the SLS and LABSA standards do not. That inference is ours, not a regulator’s statement about the other two.

The limits, and who actually sets them

• India has a limit, and it is barely ever cited. IS 11487 sets 1,4-dioxane on a 100% basis at a maximum of 30 ppm — a limit introduced by one amendment and tightened from 100 ppm to 30 ppm by a later one. Two qualifications: it is a BIS specification, so it binds where a contract or another instrument invokes it rather than of its own force, and we could not establish that any Indian law invokes it; and it sits in a cosmetic-industry standard for 30% SLES, not a detergent standard.
• New York State is the strict one, and it is now fully in force. Household cleansing and personal care products are capped at 1 ppm since 31 December 2023, having stepped down from 2 ppm; cosmetics are capped at 10 ppm. The waiver route for manufacturers who could not yet comply expired at the end of December 2025. This matters to an Indian exporter, not only to an American formulator.
• The European Union’s scientific committee holds 10 ppm to be safe in cosmetics, in an opinion adopted on 15 December 2015, which rejected a two-phase approach in favour of phasing the 10 ppm figure in over a short transition.
• The United States federal regulator sets no limit at all. It says in terms that it has not independently conducted a hazard identification and risk assessment, and that it would advise industry and the public if it found a health hazard. It runs surveys instead: the highest level in its 2008 survey was 11.6 ppm, with around 80% of samples non-detect at a 1 ppm detection limit. The 10 ppm figure that appears on its page is the European committee’s conclusion, and its page says so — but it is widely re-quoted as though it were an American limit, and it is not.

What a buyer does with this is specify it. If your product is going into a market with a limit, or into a customer’s specification that carries one, the 1,4-dioxane content of the SLES has to be a certified parameter on the certificate of analysis with a stated test method and quantitation limit, not an assumption. A result reported as “not detected” against an unstated limit answers nothing.

Neutralising LABSA is not arithmetic

If you buy LABSA, you are buying a reaction. This article will not tell you how to run it, and the reason is not caution for its own sake: the hazard is not stoichiometric, so getting the stoichiometry right does not make it safe.

Both reagents are rated for severe burns. LABSA: producer safety data sheets classify it corrosive — skin corrosion Category 1B and serious eye damage Category 1, H314, with H290 for corrosivity to metals. The ILO international chemical safety card for dodecylbenzenesulfonic acid records severe eye burns and possible loss of vision, decomposition to sulfur oxides and hydrogen sulfide above about 205 °C, attack on metals, and toxicity to aquatic organisms. Read the metals point as a flammable-gas hazard and not only a corrosion one: the United States emergency-response chemical database puts this acid in a reactive group whose members can react with active metals, iron and aluminium among them, liberating hydrogen and other toxic gases, and which generate hydrogen sulphide and sulphur oxides on contact with thiosulphates. A mild steel vessel pressed into service for the acid is the obvious failure mode in a small plant. Caustic soda, the usual base: the ILO card gives severe skin burns and eye damage, violent reaction with acids, hydrogen generation on contact with aluminium, tin, lead and zinc, and heat generation on contact with water — with the instruction never to pour water into the substance. On transport, the solid is UN 1823, Class 8, Packing Group II, while the lye solution most plants actually use is UN 1824, Class 8, Packing Group II or III depending on concentration, so take the classification from the grade you buy. This is work for a competent formulator with engineered temperature control, not for a calculation.

Four things make the arithmetic insufficient, each from a separate source:

1. The heat is local, not average. The reactive-group data the United States emergency-response database assigns this family of acids to warns that a neutralisation can release a dangerous amount of heat into a small space, and that diluting a concentrated acid can put enough heat into the small region where the streams meet to boil water there explosively and throw acid about. A batch whose overall temperature rise looks manageable can still be boiling where the streams meet.
2. The acid has to be assayed, not assumed. Producers publish the neutralisation value as a range, and IS 8401 permits free sulphuric acid up to 2% in Type 1 and up to 9% in Type 2. That free acid consumes base of its own, so two consignments both honestly described as LABSA need different quantities of caustic.
3. Neutralisation is not instantaneous. A detergent-granule process patent describes the reaction as starting in the high-shear mixer and continuing during subsequent processing, with the mixer preferably cooled to keep the temperature below 40 °C. A batch that reads neutral can still be reacting. That patent also runs its neutralising agent at a large stoichiometric excess — preferably at least five times — but read that figure in its own context and not as a caustic dose: it is a dry granulation process in which a solid carbonate is both the base and the carrier for the granule. Nothing here indicates an excess of caustic soda.
4. It foams. LABSA is described in its own producer literature as a high-foaming anionic surfactant, which is the point: the product of the reaction foams, so a vessel sized on volume arithmetic will not have the freeboard a foaming exotherm needs.

A published process description of detergent manufacture records the same thing in plain terms: powder slurry is made by reacting caustic soda with linear alkylbenzene sulphonic acid, liquids are made by neutralising with a caustic soda solution, and the neutralisation is exothermic, with the mixture heating as ingredients are added. Producer safety data sheets list uncontrolled neutralisation with bases among the things to avoid. Soda ash is a real alternative base in granulation processes — the same patent names sodium or calcium carbonate as especially suitable — but it is a different process with different equipment, not a drop-in substitution for caustic, and this article makes no claim about what it does to a liquid formulation.

Biodegradability is not environmental safety

“LABSA is biodegradable” is true and is routinely made to carry more weight than it can. Two corrections, both from the primary literature.

First, the biodegradation that is established is aerobic. An industry-consortium risk assessment of linear alkylbenzene sulphonate, revised in April 2013, gives a protective primary biodegradation half-life of about 3 hours in surface water and 7 days in agricultural soil, and removal in activated-sludge treatment plants typically in the region of 98 to 99.9%, with trickling filters averaging around 96%. Those are good numbers and they are the reason linear alkylbenzene replaced the branched material. The same report states that LAS does not pass standard tests for anaerobic biodegradation, and then argues that an anaerobic requirement would not be an effective protection measure. An independent European scientific committee agreed on the facts and disagreed on what follows from them. In an opinion adopted on 18 June 2020 it found the potential negligible in freshwater across all the environmental conditions tested, and anaerobic degradation in marine conditions only under particular conditions, its example being sandy sediments low in organic carbon. It then concluded that because the material is a very high volume substance released continuously to wastewater-impacted sites, the absence of degradation may lead to accumulation in anaerobic sediments and may therefore present a relevant environmental concern. Both of those hedges are the committee’s own and we have not strengthened them. But even hedged, it is the opposite direction of travel from the industry report’s conclusion on the same test failure. Whether sandy, low-carbon sediments are typical of sites receiving detergent effluent is our question rather than the committee’s statement. It matters wherever effluent reaches anaerobic sludge, a septic system or sediment.

Second, biodegradability and aquatic toxicity are different properties and both are true at once. The same assessment gives LAS an aquatic predicted-no-effect concentration of 0.27 mg/l. For the alkyl sulphates, a 2022 Australian evaluation classifies the group aquatic acute Category 2, H401, toxic to aquatic life, and aquatic chronic Category 3, H412, while categorising them as not persistent, not bioaccumulative and not toxic on the domestic criteria, with risk quotients below one at modelled use. The ILO card for SLS likewise flags it as toxic to aquatic life. Readily biodegradable, low risk at use concentration, and toxic to aquatic life are all accurate descriptions of the same material.

Why the myth survives is itself instructive. European detergent law gates market access on ultimate aerobic biodegradability. Regulation (EC) No 648/2004 allows surfactants meeting the ultimate aerobic criteria onto the market without further biodegradability limitation, and requires primary biodegradability to be measured for those that fail the ultimate test, as the gate on a derogation for industrial and institutional detergents. On anaerobic biodegradation it does something narrower than either side of this argument usually admits: its recitals record that the issue is not dealt with in the Regulation, that the Commission should examine it and propose action where justified, and that member states may maintain or set national rules in the meantime — which is material if you export. The upshot is that compliance is available to a material that fails the anaerobic test, and “compliant” gets read as “harmless”. The practical consequence for an Indian formulator is in the effluent, not in the claim: surfactant run-off foams through drains and will upset a treatment works.

Edition warning on the law itself, because this one turned over recently: Regulation (EU) 2026/405, the new European detergents and surfactants regulation, entered into force on 22 March 2026 and applies from 23 September 2029, repealing Regulation (EC) No 648/2004. As we read the summaries, it drops primary biodegradation from the framework and removes the industrial and institutional derogation. We have not read the new Regulation’s text, so nothing above is attributed to it — but if you are planning a European-market formulation for 2029 onwards, read it rather than this page.

We did not find an Indian effluent standard specific to the soap and detergent industry, or any Indian rule restricting phosphate in detergents outside the detergent-powder standard itself. That is the result of our search rather than a finding that none exists, and anyone needing the position should take it from Central Pollution Control Board and ministry documents directly. Separately, the Ecomark Rules were notified on 26 September 2024, replacing the 1991 scheme, with the Control Board implementing in partnership with BIS; we did not read the schedule of product criteria, so we make no claim about what they require of a detergent.

Transport and hazard classification, which are supplier-dependent

Two traps here, and both have cost exporters money.

LABSA does not always take the same UN number. Alkyl and aryl sulphonic acids in liquid form split on free sulphuric acid content, and the split is in the UN model regulations rather than any one country’s rules, so an Indian exporter meets it in the sea, road and air codes alike: UN 2586 where there is not more than 5% free sulphuric acid, and UN 2584 where there is more than 5% — both Class 8, both on the same emergency response guide. Producer safety data sheets and the ILO card for the low-free-acid material give UN 2586, Class 8, Packing Group III. Now recall that IS 8401 permits Type 2 acid slurry up to 9% free sulphuric acid. That reading of the two documents together is ours and is not a ruling — but it is enough to make “LABSA is always UN 2586” an assumption worth putting to a dangerous goods adviser with the actual free-acid figure in hand.

SLS’s transport classification is genuinely disputed, and the dispute is about physical form rather than chemical identity. Laboratory-reagent suppliers’ safety data sheets for sodium dodecyl sulphate classify it as a flammable solid, Category 2, H228, and consign it as UN 1325, flammable solid organic not otherwise specified, Class 4.1, Packing Group III, for road, sea and air alike — the two we read are dated 2016 and 2023, so this is not a position anyone has quietly dropped. Those same sheets carry serious eye damage and harmful-if-inhaled statements for the solid, which is the dust point made earlier. The ILO international chemical safety card for the same substance carries a UN classification heading with no value and a GHS entry with no flammable-solid statement — which we read as assigning no transport class, though that is a reading of an absence. A 28 to 30% aqueous SLS liquid cannot be a flammable solid at all. So the position to work from is that the classification belongs to the grade and the packaging, not to the name: the shipper takes it from the safety data sheet for the exact lot. We did not this time locate a bulk producer’s sheet stating that its SLS is not regulated for transport, so we do not attribute that position to anyone.

The general rule this leaves is the useful one. Classification belongs to the grade, the form and the packaging, and authorities and producers do not always agree. Where they differ, the conservative classification is the one to work to operationally, and the existence of the disagreement is itself the reason to read the lot’s own safety data sheet rather than a general rule or a page like this one.

HSN classification, and what we can and cannot say about it

India adopted the 2022 restructuring of heading 3402, and the old anionic, cationic and non-ionic sub-headings — 3402 11, 3402 12, 3402 13 and 3402 19 — were deleted, along with 3402 20, which was a retail-preparations line. Within the anionic group the current eight-digit lines are 3402 31 00, linear alkylbenzene sulphonic acids and their salts, and 3402 39 00, other; the import policy shown against both in the ITC(HS) notification, as we read it, is free. The heading does not stop there — it carries cationic, non-ionic and other anionic groups, and then splits the preparations by packaging: 3402 50 for preparations put up for retail sale, and the 3402 90 series, which is not for retail sale and is where the Indian tariff carries its synthetic detergent lines. That split matters to this audience more than the raw-material lines do: if you sell finished detergent in consumer packs it is the retail line you are classifying under, and if you sell it in bulk it is the 3402 90 lines. Either way you are dealing with more than two codes.

LABSA, and its sodium salt, fall to 3402 31 00, because the heading text names linear alkylbenzene sulphonic acids and their salts. SLES and SLS are anionic surfactants that are neither, so on the heading texts they fall to 3402 39 00. That second assignment is our reading of the tariff, not a ruling, and classification is the importer’s or exporter’s own responsibility — take it from your customs broker against the actual goods.

On rate: these goods sit at 18% GST under the rate notification of 17 September 2025, which superseded the 2017 notification that a great deal of published material still cites as the operative one. Note that the rate attaches to the entry rather than to the heading as a whole — the same notification carries a 5% entry under 3402 for sulphonated castor, fish or sperm oil, which is not these goods. We publish no customs duty rate, because we could not verify one from a primary source.

What we could not verify, and therefore did not write

This is here because the gaps are as useful to a buyer as the findings, and because a page that pretends to have no gaps should not be trusted.

• No comparative foam or detergency data. We found no primary head-to-head measurement of the three. That is why there is no performance rating table on this page, and why you should be sceptical of the ones you will find elsewhere.
• No Krafft temperature, no cloud point for the commercial grades, no solubility figures, and no pH for SLES 70 or LABSA as supplied. The only pH figures here are the Indian Standards’ own requirements for diluted solutions.
• No claim about which surfactant suits powder, liquid or bar. The common assertion that SLES is unsuitable for spray-dried powder, and the hydrolytic stability of ether sulphates and alkyl sulphates at low pH, are both things we could not source.
• No price, no price correlation and no market size. The feedstock chains are verified — lauric oils to lauryl alcohol for SLES and SLS, linear alkylbenzene for LABSA, with oleochemical prices moving with the oil price and with ethylene. A quantified correlation to palm kernel oil or to crude is not, so we state the mechanism and no numbers.
• No molar relationship, heat of neutralisation or caustic requirement. Deliberately. See the neutralisation section.

The short version

Four things decide this well. Buy on active matter and compare on a 100% basis, because the trade percentages are not comparable across materials and a trade percentage is not a grade. Name the Indian Standard and its type, because the free sulphuric acid in LABSA and the active matter in SLS are both type-dependent, and because both standards set minima rather than bands. Treat LABSA as a reaction you are buying, with two reagents both rated for severe burns and an exotherm, and put the work in competent hands. And if 1,4-dioxane matters to your market, make it a certified parameter on the SLES certificate with a method and a quantitation limit beside it. None of those costs anything at the enquiry stage.