Toxicology and migration
Regulatory references on this page are to EU frameworks: Regulation (EC) No. 1935/2004 (general food contact), Regulation (EU) No. 10/2011 (plastics), and IARC classifications. US regulatory references (FDA, NSF) appear only where directly relevant to a product or material. EU-specific migration limits (mg/kg food simulant) apply throughout.
The question "is this plastic safe to use with beer?" has two distinct answers depending on what you mean by safe. The first answer is about material compatibility — does the material degrade under contact with beer or cleaning chemicals, and does that degradation compromise the structural function of the component? That answer lives in the materials register and the wet-dry cycle model.
The second answer is about toxicology — if the material does degrade, are the degradation products harmful at the concentrations that might reach the beer? That is what this page addresses.
The two questions are related but not the same. A material can degrade mechanically (cracking, swelling, softening) without producing toxic degradation products. And — critically — a material can migrate harmful compounds into beer without showing any visible sign of degradation at all.
The key principle — and where it fails
For most materials, visible failure precedes meaningful toxicological concern. Chalking, whitening, cracking, dimensional change, surface crazing — these are visible signals that degradation has progressed to the point where the component should be replaced. If you inspect your equipment and it looks intact, the migration risk from those materials is generally low.
This principle fails for NRNR — Natural Rubber Vulcanised latex of Hevea brasiliensis. Used in budget grommets and washers. Carries N-nitrosamine precursor risk from sulphur-cure accelerators — invisible to inspection. Replace immediately with EPDM./SBRSBR — Styrene-Butadiene Rubber A synthetic rubber sharing NR's unsaturated backbone and sulphur-cure chemistry. Same N-nitrosamine precursor risk as NR. Replace immediately with EPDM. rubber. N-nitrosamine migration from natural rubber occurs from a structurally intact, visually normal surface. There is no inspection that can detect it. The only reliable safeguard is avoiding NRNR — Natural Rubber Vulcanised latex of Hevea brasiliensis. Used in budget grommets and washers. Carries N-nitrosamine precursor risk from sulphur-cure accelerators — invisible to inspection. Replace immediately with EPDM./SBRSBR — Styrene-Butadiene Rubber A synthetic rubber sharing NR's unsaturated backbone and sulphur-cure chemistry. Same N-nitrosamine precursor risk as NR. Replace immediately with EPDM. in food-contact applications entirely.
This distinction — the one material where the "inspect and replace when damaged" protocol does not provide meaningful protection — is the most important practical point on this page.
Risk ranking
The risks below are ranked by practical priority: the likelihood that a homebrewer encounters the material, the severity of the toxicological concern, and the degree to which the risk is invisible versus inspectable.
1. NR/SBR — N-nitrosamine precursors
Priority: Replace immediately. No exceptions.
Natural rubber (NRNR — Natural Rubber Vulcanised latex of Hevea brasiliensis. Used in budget grommets and washers. Carries N-nitrosamine precursor risk from sulphur-cure accelerators — invisible to inspection. Replace immediately with EPDM.) and styrene-butadiene rubber (SBRSBR — Styrene-Butadiene Rubber A synthetic rubber sharing NR's unsaturated backbone and sulphur-cure chemistry. Same N-nitrosamine precursor risk as NR. Replace immediately with EPDM.) are sulphur-cured rubbers. The sulphur cure system requires amine accelerators — compounds such as dibenzothiazyl disulphide (MBTS) and zinc dibutyldithiocarbamate (ZDBC) — that remain in the cured rubber as residues and continue to migrate into contact liquids over time.1
In mildly acidic conditions — beer pH 4.0–4.5 — these secondary amine accelerator residues can react with trace nitrogen oxides (which are present in fermentation headspace as products of normal yeast metabolism) to form N-nitrosamines. N-nitrosamines are classified by IARC as Group 2A (probably carcinogenic to humans) or higher. Several specific N-nitrosamines (NDMA, NDEA) have well-established carcinogenicity at low concentrations in animal studies.1
The EU has established specific migration limits for N-nitrosamines from rubber food contact materials that are among the most stringent in the entire food contact framework, reflecting the seriousness of the toxicological concern.2
The critical point: this migration does not require visible failure. An NRNR — Natural Rubber Vulcanised latex of Hevea brasiliensis. Used in budget grommets and washers. Carries N-nitrosamine precursor risk from sulphur-cure accelerators — invisible to inspection. Replace immediately with EPDM. grommet that appears intact, supple, and undamaged is still migrating nitrosamine precursors into beer in contact with it. Temperature accelerates migration — warmer fermentation temperatures increase both the rate of accelerator leaching and the rate of nitrosation. Prolonged contact time (a beer fermenting for two weeks against an NRNR — Natural Rubber Vulcanised latex of Hevea brasiliensis. Used in budget grommets and washers. Carries N-nitrosamine precursor risk from sulphur-cure accelerators — invisible to inspection. Replace immediately with EPDM. grommet) accumulates migration that a single brief exposure does not.
NRNR — Natural Rubber Vulcanised latex of Hevea brasiliensis. Used in budget grommets and washers. Carries N-nitrosamine precursor risk from sulphur-cure accelerators — invisible to inspection. Replace immediately with EPDM. grommets are present in older bucket fermenter configurations, particularly those sold without formal food contact documentation. Black rubber grommets should be treated with suspicion unless the material is positively confirmed as EPDMEPDM — Ethylene Propylene Diene Monomer A saturated-backbone elastomer rubber used in fermenter grommets and tap washers. Better chemical resistance than NR or SBR. Rated B for DDBSA in realistic homebrewing use with post-batch cleaning.. If in doubt, replace with a confirmed EPDMEPDM — Ethylene Propylene Diene Monomer A saturated-backbone elastomer rubber used in fermenter grommets and tap washers. Better chemical resistance than NR or SBR. Rated B for DDBSA in realistic homebrewing use with post-batch cleaning. grommet before the next brew. EPDMEPDM — Ethylene Propylene Diene Monomer A saturated-backbone elastomer rubber used in fermenter grommets and tap washers. Better chemical resistance than NR or SBR. Rated B for DDBSA in realistic homebrewing use with post-batch cleaning. grommets are widely available, inexpensive, and eliminate this risk category entirely.
SBRSBR — Styrene-Butadiene Rubber A synthetic rubber sharing NR's unsaturated backbone and sulphur-cure chemistry. Same N-nitrosamine precursor risk as NR. Replace immediately with EPDM. is less common in homebrewing applications than NRNR — Natural Rubber Vulcanised latex of Hevea brasiliensis. Used in budget grommets and washers. Carries N-nitrosamine precursor risk from sulphur-cure accelerators — invisible to inspection. Replace immediately with EPDM. but carries the same concern and the same recommendation.
See also: Natural rubber (NR/SBR)
2. POM (acetal) — formaldehyde migration under degradation
Priority: High. Inspect and replace any degraded POMPOM — Polyoxymethylene Also known as acetal or Delrin. An engineering thermoplastic used in John Guest push-fit fittings and older DuoTight collars. Susceptible to acid-catalysed chain-unzipping under WDC conditions, releasing formaldehyde. Rated D–X for ABNS.→ Full details fittings immediately.
Polyoxymethylene (POMPOM — Polyoxymethylene Also known as acetal or Delrin. An engineering thermoplastic used in John Guest push-fit fittings and older DuoTight collars. Susceptible to acid-catalysed chain-unzipping under WDC conditions, releasing formaldehyde. Rated D–X for ABNS.→ Full details, also called acetal) was used in the collar mechanism of DuoTight push-fit fittings in their original design and remains in use in John Guest push-fit fittings. The acetal polymer backbone cleaves under acid or alkaline catalysis, releasing formaldehyde as the primary degradation product.
Formaldehyde is an IARC Group 1 carcinogen — classified as definitely carcinogenic to humans. The EU specific migration limit for formaldehyde from food contact materials is 15 mg/kg.3 In the DuoTight failure scenario documented by KegLand's design revision, visibly degraded POMPOM — Polyoxymethylene Also known as acetal or Delrin. An engineering thermoplastic used in John Guest push-fit fittings and older DuoTight collars. Susceptible to acid-catalysed chain-unzipping under WDC conditions, releasing formaldehyde. Rated D–X for ABNS.→ Full details collars were releasing formaldehyde into beer flowing through them.4
Visible failure — chalking, whitening, surface dimpling, dimensional change at the collar — generally precedes the most significant migration levels. But early-stage POMPOM — Polyoxymethylene Also known as acetal or Delrin. An engineering thermoplastic used in John Guest push-fit fittings and older DuoTight collars. Susceptible to acid-catalysed chain-unzipping under WDC conditions, releasing formaldehyde. Rated D–X for ABNS.→ Full details degradation that has not yet produced visible surface changes can still release formaldehyde below the migration limit but above zero. The safe position is: replace any POMPOM — Polyoxymethylene Also known as acetal or Delrin. An engineering thermoplastic used in John Guest push-fit fittings and older DuoTight collars. Susceptible to acid-catalysed chain-unzipping under WDC conditions, releasing formaldehyde. Rated D–X for ABNS.→ Full details fitting that shows any surface change, and replace POMPOM — Polyoxymethylene Also known as acetal or Delrin. An engineering thermoplastic used in John Guest push-fit fittings and older DuoTight collars. Susceptible to acid-catalysed chain-unzipping under WDC conditions, releasing formaldehyde. Rated D–X for ABNS.→ Full details fittings proactively in setups where ABNSABNS — Acid-Based No-Rinse Sanitiser The class of acid-based sanitisers used in homebrewing, combining phosphoric acid with an anionic alkylbenzenesulfonate surfactant. The acid creates a low-pH environment hostile to microorganisms; the surfactant disrupts cell membranes. Examples: Star San, Sanipro Rinse, StellarSan, Chemsan. Approved for use on food-contact surfaces without rinsing when used at the manufacturer's specified dilution. has been applied to external fittings without rinsing (the wet-dry cycle mechanism that caused the original DuoTight failures).
KegLand replaced the POMPOM — Polyoxymethylene Also known as acetal or Delrin. An engineering thermoplastic used in John Guest push-fit fittings and older DuoTight collars. Susceptible to acid-catalysed chain-unzipping under WDC conditions, releasing formaldehyde. Rated D–X for ABNS.→ Full details collar with a POKPOK — Polyketone An engineering thermoplastic used in current KegLand DuoTight push-fit fittings and the RAPT Pill body. Replaced POM due to POM's vulnerability to acid-catalysed degradation under WDC conditions. A-rated for all homebrewing chemicals.→ Full details (polyketone) collar in the revised DuoTight design. John Guest fittings continue to use POMPOM — Polyoxymethylene Also known as acetal or Delrin. An engineering thermoplastic used in John Guest push-fit fittings and older DuoTight collars. Susceptible to acid-catalysed chain-unzipping under WDC conditions, releasing formaldehyde. Rated D–X for ABNS.→ Full details. If you have John Guest fittings in a gas or liquid line that contacts beer, and those fittings have been subject to repeated ABNSABNS — Acid-Based No-Rinse Sanitiser The class of acid-based sanitisers used in homebrewing, combining phosphoric acid with an anionic alkylbenzenesulfonate surfactant. The acid creates a low-pH environment hostile to microorganisms; the surfactant disrupts cell membranes. Examples: Star San, Sanipro Rinse, StellarSan, Chemsan. Approved for use on food-contact surfaces without rinsing when used at the manufacturer's specified dilution. spray-and-leave exposure without rinsing, inspection and proactive replacement is appropriate.
See also: POM/Acetal, KegLand DuoTight Design Revision
3. PC (polycarbonate) — BPA migration
Priority: Medium. Largely eliminated from current equipment; legacy items require awareness.
Polycarbonate (PC) releases bisphenol A (BPA) through hydrolysisHydrolysis The chemical reaction in which a molecule is split by water, typically at a bond that connects two parts of the molecule. In food contact materials, hydrolysis is the primary mechanism by which acid or alkaline cleaning solutions attack susceptible polymers — particularly those with ester linkages (PET, Tritan, PC) or ether linkages (POM). Polymers with all-carbon backbones (PP, HDPE, PTFE) have no hydrolysable bonds and are inherently resistant to aqueous chemical attack. of its ester linkage. BPA is not carcinogenic in the IARC classification but is a well-established endocrine disruptor with evidence of biological effects at very low concentrations. The EU has banned BPA in food contact materials for sensitive populations and has set a migration limit of 0.05 mg/kg.5
The hydrolysisHydrolysis The chemical reaction in which a molecule is split by water, typically at a bond that connects two parts of the molecule. In food contact materials, hydrolysis is the primary mechanism by which acid or alkaline cleaning solutions attack susceptible polymers — particularly those with ester linkages (PET, Tritan, PC) or ether linkages (POM). Polymers with all-carbon backbones (PP, HDPE, PTFE) have no hydrolysable bonds and are inherently resistant to aqueous chemical attack. pathway is accelerated by alkaline conditions — hot PBWPBW — Powdered Brewery Wash A sodium metasilicate and percarbonate-based alkaline cleaner widely used in brewing. Removes organic soil through alkaline hydrolysis. A-rated for all common homebrewing plastic and elastomer materials at working concentrations. on PC is the worst-case scenario for BPA release, producing the combination of high pH and elevated temperature that drives ester bond cleavage most rapidly. Beer contact at ambient temperature and beer pH (~4.0–4.5) drives hydrolysisHydrolysis The chemical reaction in which a molecule is split by water, typically at a bond that connects two parts of the molecule. In food contact materials, hydrolysis is the primary mechanism by which acid or alkaline cleaning solutions attack susceptible polymers — particularly those with ester linkages (PET, Tritan, PC) or ether linkages (POM). Polymers with all-carbon backbones (PP, HDPE, PTFE) have no hydrolysable bonds and are inherently resistant to aqueous chemical attack. more slowly; the acidic conditions actually slightly suppress it. But ethanol in beer increases BPA solubility and migration.
PC carboys, auto-siphons with PC bodies, and site glasses are the homebrewing items most likely to contain PC. Most current equipment has moved away from PC — current KegLand site glasses use materials other than PC. But if you have older PC equipment or are uncertain about the material, avoid hot alkaline cleaning and minimise sustained beer contact time.
Visual inspection does not reliably indicate whether BPA migration is occurring — PC can appear intact while slowly releasing BPA below structural failure threshold.
See also: Polycarbonate (PC)
4. PS (polystyrene) — styrene migration
Priority: Low to medium. Material- and context-specific.
Polystyrene (PSPS — Polystyrene A family of transparent, rigid styrene-based plastics used in homebrewing airlocks and accessories. Three grades appear in this register: GPPS (General-Purpose Polystyrene), SAN (Styrene-Acrylonitrile copolymer), and Styrolux SBC (styrene-butadiene block copolymer). All three are visually indistinguishable. Grade is often unspecified by manufacturers — treat as GPPS if unknown, which is the most conservative assumption for ABNS and DES compatibility.) releases styrene monomer as its primary migration concern. Styrene is an IARC Group 2A carcinogen (probably carcinogenic to humans). The EU specific migration limit for styrene from PSPS — Polystyrene A family of transparent, rigid styrene-based plastics used in homebrewing airlocks and accessories. Three grades appear in this register: GPPS (General-Purpose Polystyrene), SAN (Styrene-Acrylonitrile copolymer), and Styrolux SBC (styrene-butadiene block copolymer). All three are visually indistinguishable. Grade is often unspecified by manufacturers — treat as GPPS if unknown, which is the most conservative assumption for ABNS and DES compatibility. food contact materials is 0.045 mg/kg — among the most conservative in the EU food contact framework, reflecting the carcinogenicity classification.3
The relevance to homebrewing is primarily through airlocks. Many compact and S-shaped airlocks are manufactured from general-purpose polystyrene (GPPSGPPS — General-Purpose Polystyrene The standard grade of polystyrene — amorphous, rigid, transparent, and inexpensive. Carries RIC code 6. Susceptible to DDBSA-driven environmental stress cracking (ESC) under WDC conditions — rated B at working dilution, D under accumulated WDC. Confirmed in Enolandia compact airlock (cod. 14037/14038) and cylindrical fermenter with float (cod. 11965) by Declaration of Conformity.). DDBSADDBSA — Dodecylbenzenesulfonic acid The active surfactant in acid-based no-rinse sanitisers (ABNS). A long-chain anionic surfactant that disrupts microbial cell membranes at low pH. Non-volatile — it concentrates on surfaces as water evaporates. — the active ingredient in ABNSABNS — Acid-Based No-Rinse Sanitiser The class of acid-based sanitisers used in homebrewing, combining phosphoric acid with an anionic alkylbenzenesulfonate surfactant. The acid creates a low-pH environment hostile to microorganisms; the surfactant disrupts cell membranes. Examples: Star San, Sanipro Rinse, StellarSan, Chemsan. Approved for use on food-contact surfaces without rinsing when used at the manufacturer's specified dilution. — has a π–π stacking interaction with the aromatic rings in PSPS — Polystyrene A family of transparent, rigid styrene-based plastics used in homebrewing airlocks and accessories. Three grades appear in this register: GPPS (General-Purpose Polystyrene), SAN (Styrene-Acrylonitrile copolymer), and Styrolux SBC (styrene-butadiene block copolymer). All three are visually indistinguishable. Grade is often unspecified by manufacturers — treat as GPPS if unknown, which is the most conservative assumption for ABNS and DES compatibility. that can mobilise residual styrene monomer and oligomers from the PSPS — Polystyrene A family of transparent, rigid styrene-based plastics used in homebrewing airlocks and accessories. Three grades appear in this register: GPPS (General-Purpose Polystyrene), SAN (Styrene-Acrylonitrile copolymer), and Styrolux SBC (styrene-butadiene block copolymer). All three are visually indistinguishable. Grade is often unspecified by manufacturers — treat as GPPS if unknown, which is the most conservative assumption for ABNS and DES compatibility. matrix. At working-dilution ABNSABNS — Acid-Based No-Rinse Sanitiser The class of acid-based sanitisers used in homebrewing, combining phosphoric acid with an anionic alkylbenzenesulfonate surfactant. The acid creates a low-pH environment hostile to microorganisms; the surfactant disrupts cell membranes. Examples: Star San, Sanipro Rinse, StellarSan, Chemsan. Approved for use on food-contact surfaces without rinsing when used at the manufacturer's specified dilution. concentrations this effect is limited. At the CFCF — Concentration Factor How many times more concentrated the non-volatile residue is compared to the original working solution, after evaporation. CF at complete drying is set by the product's working dilution: CF = 1,000 ÷ dose in mL/L. For StellarSan at 1.5 mL/L, CF ≈ 667.=250 dry residue conditions produced by the wet-dry cycle, it becomes more significant.
The specific scenario of concern: a PSPS — Polystyrene A family of transparent, rigid styrene-based plastics used in homebrewing airlocks and accessories. Three grades appear in this register: GPPS (General-Purpose Polystyrene), SAN (Styrene-Acrylonitrile copolymer), and Styrolux SBC (styrene-butadiene block copolymer). All three are visually indistinguishable. Grade is often unspecified by manufacturers — treat as GPPS if unknown, which is the most conservative assumption for ABNS and DES compatibility. airlock used as a reservoir for working-dilution ABNSABNS — Acid-Based No-Rinse Sanitiser The class of acid-based sanitisers used in homebrewing, combining phosphoric acid with an anionic alkylbenzenesulfonate surfactant. The acid creates a low-pH environment hostile to microorganisms; the surfactant disrupts cell membranes. Examples: Star San, Sanipro Rinse, StellarSan, Chemsan. Approved for use on food-contact surfaces without rinsing when used at the manufacturer's specified dilution. fill liquid, subject to repeated wet-dry cycling as the airlock top evaporates and is refilled. This geometry (confined, not drained, repeatedly re-wetted) produces conditions closer to sustained WDCWDC — Wet-Dry Cycle The process by which liquid applied to a surface evaporates, leaving non-volatile components concentrated as a dry residue. A single WDC deposits concentrated DDBSA and phosphoric acid on every sanitised surface. Repeated WDC events without cleaning cause residue to accumulate, progressively increasing exposure. Post-brew cleaning resets accumulation to zero. See: The wet-dry cycle model. exposure than a fermenter body. A better practice: use working-dilution ABNSABNS — Acid-Based No-Rinse Sanitiser The class of acid-based sanitisers used in homebrewing, combining phosphoric acid with an anionic alkylbenzenesulfonate surfactant. The acid creates a low-pH environment hostile to microorganisms; the surfactant disrupts cell membranes. Examples: Star San, Sanipro Rinse, StellarSan, Chemsan. Approved for use on food-contact surfaces without rinsing when used at the manufacturer's specified dilution. or undiluted glycerol as airlock fill, not repeatedly topping up — or confirm that the airlock is SANSAN — Styrene-Acrylonitrile copolymer A transparent plastic used in some airlocks and equipment. The acrylonitrile content gives better chemical resistance than GPPS, particularly against DDBSA in acid-based sanitisers. Rated A for ABNS, unlike GPPS which is rated B/D. (styrene-acrylonitrile copolymer) rather than GPPSGPPS — General-Purpose Polystyrene The standard grade of polystyrene — amorphous, rigid, transparent, and inexpensive. Carries RIC code 6. Susceptible to DDBSA-driven environmental stress cracking (ESC) under WDC conditions — rated B at working dilution, D under accumulated WDC. Confirmed in Enolandia compact airlock (cod. 14037/14038) and cylindrical fermenter with float (cod. 11965) by Declaration of Conformity..
GPPSGPPS — General-Purpose Polystyrene The standard grade of polystyrene — amorphous, rigid, transparent, and inexpensive. Carries RIC code 6. Susceptible to DDBSA-driven environmental stress cracking (ESC) under WDC conditions — rated B at working dilution, D under accumulated WDC. Confirmed in Enolandia compact airlock (cod. 14037/14038) and cylindrical fermenter with float (cod. 11965) by Declaration of Conformity. vs. SANSAN — Styrene-Acrylonitrile copolymer A transparent plastic used in some airlocks and equipment. The acrylonitrile content gives better chemical resistance than GPPS, particularly against DDBSA in acid-based sanitisers. Rated A for ABNS, unlike GPPS which is rated B/D.: SANSAN — Styrene-Acrylonitrile copolymer A transparent plastic used in some airlocks and equipment. The acrylonitrile content gives better chemical resistance than GPPS, particularly against DDBSA in acid-based sanitisers. Rated A for ABNS, unlike GPPS which is rated B/D. is a copolymer that does not share the π–π interaction vulnerability. Many airlocks are SANSAN — Styrene-Acrylonitrile copolymer A transparent plastic used in some airlocks and equipment. The acrylonitrile content gives better chemical resistance than GPPS, particularly against DDBSA in acid-based sanitisers. Rated A for ABNS, unlike GPPS which is rated B/D. rather than GPPSGPPS — General-Purpose Polystyrene The standard grade of polystyrene — amorphous, rigid, transparent, and inexpensive. Carries RIC code 6. Susceptible to DDBSA-driven environmental stress cracking (ESC) under WDC conditions — rated B at working dilution, D under accumulated WDC. Confirmed in Enolandia compact airlock (cod. 14037/14038) and cylindrical fermenter with float (cod. 11965) by Declaration of Conformity., but the distinction is not reliably documented by homebrew equipment manufacturers. The Enolandia compact airlock material has not been confirmed to this documentation (confirmation request pending). Until confirmed, treat unknown PSPS — Polystyrene A family of transparent, rigid styrene-based plastics used in homebrewing airlocks and accessories. Three grades appear in this register: GPPS (General-Purpose Polystyrene), SAN (Styrene-Acrylonitrile copolymer), and Styrolux SBC (styrene-butadiene block copolymer). All three are visually indistinguishable. Grade is often unspecified by manufacturers — treat as GPPS if unknown, which is the most conservative assumption for ABNS and DES compatibility. airlocks as GPPSGPPS — General-Purpose Polystyrene The standard grade of polystyrene — amorphous, rigid, transparent, and inexpensive. Carries RIC code 6. Susceptible to DDBSA-driven environmental stress cracking (ESC) under WDC conditions — rated B at working dilution, D under accumulated WDC. Confirmed in Enolandia compact airlock (cod. 14037/14038) and cylindrical fermenter with float (cod. 11965) by Declaration of Conformity. and minimise sustained ABNSABNS — Acid-Based No-Rinse Sanitiser The class of acid-based sanitisers used in homebrewing, combining phosphoric acid with an anionic alkylbenzenesulfonate surfactant. The acid creates a low-pH environment hostile to microorganisms; the surfactant disrupts cell membranes. Examples: Star San, Sanipro Rinse, StellarSan, Chemsan. Approved for use on food-contact surfaces without rinsing when used at the manufacturer's specified dilution. contact with the airlock body material.
See also: PS and SAN
5. DDBSA in beer from ABNS residue
Priority: Negligible in normal use. Calculated, not assumed.
The wet-dry cycle model provides the quantitative answer: approximately 4.2 mg of non-volatile DDBSADDBSA — Dodecylbenzenesulfonic acid The active surfactant in acid-based no-rinse sanitisers (ABNS). A long-chain anionic surfactant that disrupts microbial cell membranes at low pH. Non-volatile — it concentrates on surfaces as water evaporates. and phosphoric acid residue remains on the interior surfaces of a 20 L fermenter after correct gravity drainage. When wortWort Liquid extracted from malted grain during mashing and boiling, before fermentation. The starting point for beer. is added, this residue dissolves and produces a DDBSADDBSA — Dodecylbenzenesulfonic acid The active surfactant in acid-based no-rinse sanitisers (ABNS). A long-chain anionic surfactant that disrupts microbial cell membranes at low pH. Non-volatile — it concentrates on surfaces as water evaporates. concentration of approximately 0.21 ppm in the wortWort Liquid extracted from malted grain during mashing and boiling, before fermentation. The starting point for beer..
The flavour detection threshold for DDBSADDBSA — Dodecylbenzenesulfonic acid The active surfactant in acid-based no-rinse sanitisers (ABNS). A long-chain anionic surfactant that disrupts microbial cell membranes at low pH. Non-volatile — it concentrates on surfaces as water evaporates. in beer is approximately 1–5 ppm. The worst-case calculation produces a concentration 5–25 times below the flavour threshold, and orders of magnitude below any acute toxicological threshold.
The calculation is important precisely because it is a calculation, not an assertion. "Don't worry about Star SanSAN — Styrene-Acrylonitrile copolymer A transparent plastic used in some airlocks and equipment. The acrylonitrile content gives better chemical resistance than GPPS, particularly against DDBSA in acid-based sanitisers. Rated A for ABNS, unlike GPPS which is rated B/D. foam" is a common homebrewing instruction; the WDCWDC — Wet-Dry Cycle The process by which liquid applied to a surface evaporates, leaving non-volatile components concentrated as a dry residue. A single WDC deposits concentrated DDBSA and phosphoric acid on every sanitised surface. Repeated WDC events without cleaning cause residue to accumulate, progressively increasing exposure. Post-brew cleaning resets accumulation to zero. See: The wet-dry cycle model. model shows why that instruction is valid, and where the margin is, so you can evaluate it rather than simply accepting it.
The margin is not thin. You would need approximately 40,000 pints of beer made in this fermenter to approach the acute oral toxicity threshold for DDBSADDBSA — Dodecylbenzenesulfonic acid The active surfactant in acid-based no-rinse sanitisers (ABNS). A long-chain anionic surfactant that disrupts microbial cell membranes at low pH. Non-volatile — it concentrates on surfaces as water evaporates.. The no-rinse approval is validated by the numbers.
6. Microplastics
Priority: Low. Sources predominantly environmental. Discussed separately.
Microplastics are present in beer regardless of packaging material — including in glass-bottled commercially produced beer, which in some studies contains higher microplastic counts than PETPET — Polyethylene terephthalate The plastic used in the FermZilla All Rounder, Oxebar mini keg, and PET bottles. Recycling code ♻️1. Extensively tested for food contact with carbonated beverages. Do not exceed 40 °C when cleaning.-bottled beer. The sources are predominantly environmental and process-related. The risk from homebrewing plastic equipment specifically is not meaningfully elevated compared to commercial production.
This topic is developed fully in the Microplastics page. The toxicology risk ranking here reflects the current scientific position that microplastics in beer at measured concentrations have not been shown to cause harm at doses typical of beer consumption, while acknowledging that the evidence base is incomplete.
The regulatory framework
Food contact materials in the EU operate under Regulation (EC) No. 1935/2004, which establishes the general principle that materials must not transfer constituents to food in quantities that endanger human health, bring about an unacceptable change in the composition of the food, or bring about a deterioration in the organolepticOrganoleptic Relating to the sensory properties of a food or drink — taste, smell, appearance, and texture. EU food contact regulations require that materials do not cause unacceptable organoleptic changes to food. characteristics of the food.
Plastics are regulated specifically under Regulation (EU) No. 10/2011, which sets specific migration limits (SMLSML — Specific Migration Limit The maximum permitted amount of a substance that may migrate from a food contact material into food or a food simulant, set by EU Regulation 10/2011. Expressed in mg/kg of food.) for listed monomers and additives, an overall migration limit (OMLOML — Overall Migration Limit The maximum total amount of all substances that may migrate from a food contact material into food or a food simulant under EU Regulation 10/2011, set at 10 mg/dm² of contact surface (or 60 mg/kg of food for articles where dm² is impractical to measure). The OML is a ceiling on total migration; individual substances also have their own Specific Migration Limits (SMLs) which may be more restrictive. A DoC that shows overall migration within 10 mg/dm² confirms OML compliance but does not reveal how close individual additives are to their own SMLs.) of 10 mg/kg food simulant, and a positive list of permitted substances. Materials complying with Regulation 10/2011 and carrying a Declaration of Conformity (DoCDoC — Declaration of Conformity A manufacturer's written statement that a food contact material or article complies with the applicable EU regulations (primarily 1935/2004 and 10/2011). Required at each stage of the commercial supply chain, but not legally required to be provided to end consumers at retail.) have been assessed for migration within the constraints of that regulation.
The EU migration limits cited on this page — formaldehyde (15 mg/kg), styrene (0.045 mg/kg), BPA (0.05 mg/kg) — are SMLSML — Specific Migration Limit The maximum permitted amount of a substance that may migrate from a food contact material into food or a food simulant, set by EU Regulation 10/2011. Expressed in mg/kg of food. values from Regulation 10/2011 Annex I.
A DoCDoC — Declaration of Conformity A manufacturer's written statement that a food contact material or article complies with the applicable EU regulations (primarily 1935/2004 and 10/2011). Required at each stage of the commercial supply chain, but not legally required to be provided to end consumers at retail. is necessary but not sufficient. Compliance with Regulation 10/2011 is assessed under standardised test conditions. Non-standard use — elevated temperatures, ABNSABNS — Acid-Based No-Rinse Sanitiser The class of acid-based sanitisers used in homebrewing, combining phosphoric acid with an anionic alkylbenzenesulfonate surfactant. The acid creates a low-pH environment hostile to microorganisms; the surfactant disrupts cell membranes. Examples: Star San, Sanipro Rinse, StellarSan, Chemsan. Approved for use on food-contact surfaces without rinsing when used at the manufacturer's specified dilution. cleaning agents, repeated wet-dry cycling — can produce conditions outside the scope of the compliance testing. The analysis in this documentation addresses these non-standard conditions directly.
Dose-response and the precautionary position
For most substances, regulatory migration limits are set at levels where risk assessment frameworks consider exposure acceptable — not zero, but within a range judged to carry negligible risk given normal patterns of food consumption. For a homebrewer consuming perhaps 50–100 litres of their own beer per year from equipment they control, the aggregate exposure from any single migration source is expected to be very low.
For carcinogens and endocrine disruptors — formaldehyde, styrene, BPA, N-nitrosamines — there is legitimate scientific debate about whether safe thresholds exist at all. The regulatory limits are set based on risk assessment models; they are not statements that exposure below the limit carries no risk. For homebrewers, the correct precautionary position is: avoid exposure where practical, without treating the concern as greater than the evidence supports.
Replacing an NRNR — Natural Rubber Vulcanised latex of Hevea brasiliensis. Used in budget grommets and washers. Carries N-nitrosamine precursor risk from sulphur-cure accelerators — invisible to inspection. Replace immediately with EPDM. grommet with EPDMEPDM — Ethylene Propylene Diene Monomer A saturated-backbone elastomer rubber used in fermenter grommets and tap washers. Better chemical resistance than NR or SBR. Rated B for DDBSA in realistic homebrewing use with post-batch cleaning. is practical, inexpensive, and eliminates a category of risk entirely. That is the right response to the nitrosamine concern. Discarding a functional PETPET — Polyethylene terephthalate The plastic used in the FermZilla All Rounder, Oxebar mini keg, and PET bottles. Recycling code ♻️1. Extensively tested for food contact with carbonated beverages. Do not exceed 40 °C when cleaning. fermenter because microplastics are detectable in beer from all sources is a response that is not proportionate to the evidence.