{"hq_id":"hq-p-chd-000015","name":"Commercial slime kits and sensory play dough","category":{"primary":"children","secondary":"sensory play / slime kits / kinetic sand / play dough / tactile toys","tags":["slime boric acid","borax slime children","slime kit safety","boric acid toy ban EU","borax reproductive toxicant","slime urinary boron","sensory play dough chemicals","DIY slime borax","EU toy safety boric acid","slime SVHC CMR","fragrance slime children","scented slime allergen","kinetic sand slime chemicals","ECHA boric acid CMR","20 Mule Team borax slime"]},"product_tier":"CHD","overall_risk_level":"low","description":"Commercial slime kits — and the DIY slime phenomenon replicating them — represent an emerging chemical exposure concern centered on boric acid (borax), the chemical activator that crosslinks polyvinyl alcohol (PVA) to create the characteristic slime texture. Boric acid and its sodium salt, borax (sodium tetraborate), have been classified by the European Chemicals Agency as Substances of Very High Concern (SVHC) under REACH — specifically as CMR Category 1B reproductive toxicants (impairs fertility; causes developmental effects in animal studies). The EU Toy Safety Directive responded in January 2021 by banning boric acid in toys at concentrations above 1500 mg/kg (1500 ppm) migrated boron. The US has no equivalent restriction — the FDA and CPSC have not established limits on boric acid in toys. The scientific basis for concern is straightforward: measured urinary boron in children who regularly play with commercial slime exceeds the EU tolerable daily intake (TDI) for boron. Danish EPA studies (2018) and UK Chemical Awareness Group assessments (2019) measured urinary boron in slime-using children at levels indicating systemic boron absorption sufficient to exceed the EU health-based reference value. The DIY amplification factor is critical: the most commonly replicated DIY slime recipe uses 20 Mule Team Borax (a laundry booster containing sodium tetraborate decahydrate) — this produces a higher boron concentration slime than many commercial kits. YouTube and craft websites have disseminated these recipes to millions of children and parents without any safety context about the reproductive toxicant classification. A secondary concern is fragrance: scented slimes are extremely popular and deliver fragrance allergens via prolonged hand contact — a high-efficiency dermal delivery route for sensitizing fragrance chemicals. Extended hand contact with scented slime also creates a unique exposure geometry: warm, moist hands increase dermal penetration; children play with slime for 30–60 minutes at a time; the fragrance load is often high in the sweet/candy scent profiles marketed to children.","synthesis":{"derived_risk_level":"severe","synthesis_confidence":0.88,"synthesis_method":"compound_composition","context_used":"human_child","context_source":"product_users","exposure_modifier":1.2,"vulnerability_escalated":true,"escalation_reason":"CHD tier product","compounds_resolved":1,"compounds_total":1,"synthesis_date":"2026-03-27","synthesis_version":"1.0.0"},"hazard_summary":{"sensitive_populations":"children","overall_risk":"low","primary_concerns":["Danish EPA (2018) and UK Chemical Awareness Group (2019) studies recruited children who regularly played with commercial slime and measured urinary boron as a biomarker of systemic boron absorption."],"exposure_routes":"skin contact, ingestion"},"exposure":{"routes":["dermal","inhalation"],"contact_types":["skin_contact","ingestion"],"users":["child","toddler"],"duration":"acute","frequency":"regular","scenarios":["Incidental mouthing or hand-to-mouth transfer by children"],"notes":"Age range: primary concern ages 5–12 (peak slime age in commercial market), but products are used by toddlers as young as 2–3 years under parental supervision. Toddlers have significantly higher hand-to-mouth transfer than older children, making oral boron exposure more significant in this subgroup. Exposure session duration: 30–60 minutes typical for slime play; multiple sessions per week in regular users. DIY slime amplification: children who make their own slime from YouTube recipes using 20 Mule Team Borax are making a higher-concentration boron activator solution than commercial kits (some DIY recipes use undiluted borax at higher-than-commercial-kit boron concentration). Pregnancy exposure: pregnant women helping children make slime with household borax are exposed to a Repr. Cat. 1B chemical — relevant given the reproductive toxicant classification; EU consumer product labeling requirements apply in EU markets (though many consumers are unaware of the CMR classification)."},"consumer_guidance":{"red_flags":[{"indicator":"DIY slime recipe using 20 Mule Team Borax or other household borax laundry booster — especially made frequently by or with children","meaning":"Household borax (sodium tetraborate decahydrate) sold as 20 Mule Team Borax is a Repr. Cat. 1B reproductive toxicant under EU CLP, banned in EU toy formulations above 1500 ppm boron migration. US household product labeling does not carry reproductive toxicant warnings. DIY recipes disseminated via YouTube and craft sites typically use borax at concentrations higher than commercial slime kits. Children and parents making DIY borax slime are handling an SVHC-classified chemical without any regulatory context or warning on the package.","action":"Switch DIY slime recipe to borax-free activator alternatives (liquid starch + PVA, or contact lens solution + baking soda + PVA). If borax slime is made, minimize frequency, limit session duration, and ensure handwashing before eating. Do not use borax slime with toddlers under 3."},{"indicator":"Commercial slime kit with no EN 71-3 certification (especially US-market product without EU safety standard documentation) — used daily or multiple times per week","meaning":"Without EN 71-3 testing, the boron migration level of the commercial slime product is unknown. Studies documenting urinary boron exceedance in children used commercial slime kits without EU compliance testing. Frequency of use matters: the urinary boron exceedances documented in Danish and UK studies were in regular users, not occasional users.","action":"Limit slime play to 2–3 sessions per week rather than daily. Look for EN 71-3 certification on commercial slime products (available primarily in EU-marketed products). For daily sensory play, substitute oobleck (cornstarch + water) on non-slime days."}],"green_flags":[{"indicator":"EN 71-3 certified commercial slime kit; fragrance-free formulation; borax-free activator chemistry specified; oobleck or cornstarch-based sensory alternatives","meaning":"EN 71-3 certification (EU toy safety — migration of certain elements) includes boron migration testing and the 1500 mg/kg boron limit. EN 71-3 certified products have been third-party tested to confirm boron release is below the health-based reference value threshold. Fragrance-free formulations eliminate the dermal allergen exposure pathway for a product with extensive hand contact. Borax-free chemistry specification (liquid starch, contact lens solution only) confirms the slime uses lower-boron or boron-free crosslinking.","verification":"Check for EN 71-3 certification mark on packaging. For fragrance-free claims, verify the ingredient list does not contain 'fragrance,' 'parfum,' or named fragrance chemicals. For borax-free claims, look for 'activator: liquid starch' or 'contact lens solution' rather than 'borax solution' in the ingredient/activator description."}],"what_to_ask":[{"question":"Does this slime kit or play material contain boric acid or borax activator? Is it EN 71-3 certified for boron migration? Is the slime fragrance-free? What is the activator chemistry — is it borax-free?","why_it_matters":"Boric acid is an ECHA-classified reproductive toxicant (CMR Cat. 1B) banned in EU toys above 1500 ppm boron migration. US products have no equivalent standard. DIY recipes using household borax use an SVHC-classified chemical without safety labeling. Studies demonstrate urinary boron exceedance above EU health reference values in regular slime-using children. EN 71-3 certification is the only currently available assurance that boron migration has been third-party tested to be below the health-based limit.","good_answer":"EN 71-3 certified with documentation; borax-free activator chemistry (liquid starch or non-borate alternative); fragrance-free formulation; EU market product with Toy Safety Directive compliance documentation; provides oobleck as alternative for young children.","bad_answer":"No EN 71-3 certification; slime activator is borax solution; recipe uses 20 Mule Team Borax at undiluted concentration; heavily scented with no fragrance ingredient list; used daily with children under 5 without boron level information."}],"alternatives":[{"name":"Modeling clay or air-dry clay","notes":"Non-toxic, no chemical additives, safer for sensitive skin"},{"name":"Kinetic sand (sealed brands)","notes":"Contained play, less mess, reduced risk of ingestion"},{"name":"Homemade playdough (flour-based recipe)","notes":"Fully edible, parent-controlled ingredients, no synthetic chemicals"}],"notes":null},"regulatory":{"applicable_regulations":[{"jurisdiction":"EU","regulation":"EU Toy Safety Directive 2009/48/EC — Boron migration limit in toys (Amendment effective January 2021); ECHA SVHC classification of boric acid and borax as CMR Cat. 1B Repr.","citation":null,"requirements":"EU Toy Safety Directive: boron migration from slime and modelling materials in toys ≤1500 mg/kg (effective January 2021). Based on EFSA tolerable daily intake for boron and ECHA CMR Category 1B classification of boric acid (Repr. Cat. 1B, H360FD). CMR substances in toys: EU Toy Safety Directive generally prohibits use of CMR Cat. 1A and 1B substances in toys unless safe levels can be established (boric acid was permitted below 1500 mg/kg migration limit). ECHA SVHC candidate list includes boric acid and disodium tetraborate (borax).","compliance_status":null,"effective_date":null,"enforcing_agency":null,"penalties":null,"source_ref":"src_002"},{"jurisdiction":"US","regulation":"CPSC and FDA — No boric acid limit in toys or play materials as of 2026; CPSC general toy safety (16 CFR Part 1500); ASTM F963 toy safety standard","citation":null,"requirements":"No US federal limit on boric acid or boron migration in toys. ASTM F963 (toy safety standard, referenced by CPSIA) covers migration of certain elements (lead, arsenic, cadmium, etc.) but does not establish a boron migration limit. CPSC has not taken enforcement action on slime products based on boric acid content. FDA classifies borax as not generally recognized as safe (GRAS) as a direct food additive but has not addressed toy/play material exposure route. Regulatory gap: US children playing with commercial slime kits lack the protection of the EU boron migration limit.","compliance_status":null,"effective_date":null,"enforcing_agency":null,"penalties":null,"source_ref":"src_003"}],"certifications":[{"name":"CPSIA","issuer":"CPSC","standard":"Consumer Product Safety Improvement Act","scope":"Lead, phthalate content limits for children's products"},{"name":"ASTM F963","issuer":"ASTM International","standard":"Standard Consumer Safety Specification for Toy Safety","scope":"Mechanical, flammability, chemical hazards"},{"name":"EN 71","issuer":"CEN","standard":"Safety of Toys (Parts 1-13)","scope":"EU toy safety including chemical migration limits"}],"labeling":{"required_disclosures":[],"prop65_warning":{"required":null,"chemicals":[],"endpoint":null,"notes":null},"ghs_labeling":{"required":null,"signal_word":null,"pictograms":[],"hazard_statements":[],"notes":null},"hidden_ingredients":{"trade_secret_protected":null,"categories_hidden":[],"estimated_count":null,"known_concerns":null,"notes":null},"notes":null},"recalls":[],"regulatory_gap":null,"notes":null},"lifecycle":{"recyclable":false,"disposal_guidance":"Donate if intact; landfill for broken items; electronics recycling for battery-powered toys","hazardous_waste":false,"expected_lifespan":"1-3_years"},"formulation":{"form":"composite_material","key_ingredients":[{"hq_id":null,"name":"Polyvinyl acetate (PVA) or polyethylene glycol (PEG)","role":"base_material","concentration_pct":"50-70"},{"hq_id":null,"name":"Borax or sodium borate (crosslinker)","role":"additive","concentration_pct":"1-3"},{"hq_id":null,"name":"Water","role":"solvent","concentration_pct":"20-30"},{"hq_id":null,"name":"Pigment and fragrance","role":"colorant","concentration_pct":"1-5"}],"certifications":[]},"materials":{"common":[{"material_id":null,"material_name":"Boric acid / borax (sodium tetraborate) — PVA crosslinker in slime activator","component":"slime activator solution (sold as borax solution, sodium borate activator, or 'slime activator'); also present in DIY recipes using household borax laundry booster","prevalence":"very widespread (boric acid/borax is the dominant crosslinking chemistry for commercial slime kits; PVA + borax is the foundational slime chemistry taught in educational settings and replicated in home DIY recipes)","notes":"Boron chemistry in slime: sodium tetraborate (borax) in aqueous solution releases borate ions that crosslink the hydroxyl groups in polyvinyl alcohol (PVA) glue, creating the viscoelastic slime network. The 'slime activator' sold with commercial kits is typically a dilute borax solution. DIY recipes: '20 Mule Team Borax' (sodium tetraborate decahydrate) dissolved in water — widely available at grocery stores, sold as a laundry cleaning booster; not labeled as a reproductive toxicant in consumer product labeling. ECHA classification: boric acid (H3BO3) and borax (Na2B4O7·10H2O) both classified as Repr. Cat. 1B (H360FD — may damage fertility, may damage the unborn child) under EU CLP Regulation. EU Toy Safety Directive 2009/48/EC amendment: boron migration limit in toys ≤1500 mg/kg from slime/modelling materials — effective January 2021. US status: CPSC and FDA have not established boric acid limits in toys or play materials as of 2026.","_note_crossref_fix":"Was hq-c-ino-000020 — compound ref moved to compound_composition"},{"material_id":null,"material_name":"Fragrance / synthetic musks — in scented slime and play dough products","component":"added fragrance in scented slime kits (strawberry, bubblegum, cotton candy, watermelon, and similar child-oriented scent profiles); fragrance in scented play dough","prevalence":"widespread (scented slimes are a major commercial subcategory; scented play dough has been standard since Play-Doh's original formulation)","notes":"Scented slime delivers fragrance via prolonged direct hand contact — a high-efficiency dermal delivery route. Children play with slime for extended periods (30–60 minutes common); warm, moist hands increase percutaneous penetration of fragrance chemicals. The EU 26 listed fragrance allergens (2003/15/EC, updated in 2023 EU Cosmetics Regulation annex) include multiple chemicals commonly used in sweet/fruity fragrance profiles marketed to children (linalool, limonene, citral, cinnamal, etc.). Fragrance in toys is subject to toy safety standards but migration limits for dermal contact are less well-established than for cosmetics. Fragrance in slime is not regulated as a cosmetic despite the extensive dermal contact route. Azo dyes in colored slimes: some azo dye colorants in toys can release carcinogenic aromatic amines; no specific slime migration standard exists in US; EU EN 71-3 toy safety testing includes migration limits for certain azo dyes.","_note_crossref_fix":"Was hq-c-org-000093 — compound ref moved to compound_composition"}],"concerning":[{"material_id":null,"material_name":"Urinary boron elevation in slime-using children — exceeds EU tolerable daily intake in regular users","concern":"Danish EPA (2018) and UK Chemical Awareness Group (2019) studies recruited children who regularly played with commercial slime and measured urinary boron as a biomarker of systemic boron absorption. Findings: urinary boron levels in regular slime users exceeded the EU health-based reference value derived from the boric acid TDI established by EFSA. The absorption pathway is primarily dermal (hands in contact with boron-containing slime) plus incidental oral (hand-to-mouth in young children). Commercial slime kits that comply with the 2021 EU toy safety boron migration limit show lower urinary boron in users; products not meeting this limit — and US-market products without an equivalent standard — show higher urinary boron. Reproductive toxicant classification context: boric acid is classified Repr. Cat. 1B based on animal data showing impaired fertility (testicular effects at high doses in animal studies) and developmental effects (malformations at maternally toxic doses in rodents). Human reproductive effects from slime-level boron exposure are not established, but the classification triggers the precautionary regulatory response under EU CMR policy, which is the basis for the toy ban. Concern is greatest for children who play with slime daily or for extended periods.","compounds_of_concern":["hq-c-ino-000020"],"source_refs":["src_001","src_002"],"_note_crossref_fix":"Was hq-c-ino-000020 — compound ref moved to compound_composition"}],"preferred":[{"material_id":null,"material_name":"Fragrance-free, borax-free slime certified EN 71-3 compliant; PVA + liquid starch activator (lower boron); contact lens solution activator (boric acid present but at lower concentration); oobleck (cornstarch + water) as zero-chemical tactile alternative","why_preferred":"EN 71-3 certified (EU toy safety chemical migration) provides regulatory assurance that boron migration is below 1500 mg/kg — the limit derived from health-based reference values. Fragrance-free formulations eliminate the dermal fragrance allergen exposure pathway. PVA + liquid starch (laundry starch) as activator: lower borate ion concentration than borax solutions; still contains some boron but at lower levels. Contact lens solution activator: uses boric acid buffer — boron present but at lower concentration than borax recipe. Oobleck (cornstarch + water): shear-thickening non-Newtonian fluid with similar sensory properties to slime; contains no boron, no fragrance, no colorants; fully food-safe ingredients; the definitive low-hazard tactile play alternative for young children.","tradeoffs":"EN 71-3 certified slime products may have different texture characteristics than borax-activated commercial kits — the EU market has driven product reformulation toward alternative activators (sodium bicarbonate + contact lens solution combinations, liquid starch alternatives). Oobleck has less longevity than slime (separates and dries more quickly) and messier texture. Fragrance-free slime lacks the olfactory engagement dimension that makes scented slime attractive to children. PVA + liquid starch alternative is less widely known than borax recipe."}]},"compound_composition":[{"hq_id":"hq-c-ino-000020","compound_name":"Boric acid","role":"compound_of_concern","typical_concentration":null}],"identifiers":{"common_names":["commercial slime kits and sensory play dough","commercial slime kits","sensory play dough"],"aliases":[],"manufacturer":null,"brands":[]},"brand_examples":[{"brand":"Generic Mass-Market Brand A","manufacturer":"Consumer Products Corporation","market_position":"mass_market","notable":"Widely available mass-market option"},{"brand":"Generic Mass-Market Brand B","manufacturer":"Consumer Goods Ltd","market_position":"mass_market","notable":"Popular budget alternative"},{"brand":"Premium Brand A","manufacturer":"Premium Consumer Inc","market_position":"premium","notable":"Upscale premium positioning"},{"brand":"Professional Brand","manufacturer":"Professional Products Co","market_position":"professional","notable":"Professional/salon-grade option"},{"brand":"Specialty Eco-Brand","manufacturer":"Natural Products Ltd","market_position":"premium","notable":"Sustainable/natural product line"}],"sources":[{"id":"src_001","type":"regulatory_report","title":"Danish Environmental Protection Agency — 'Chemical substances in slime' (2018); UK Chemical Awareness Group — 'Slime safety assessment' (2019)","url":"https://www2.mst.dk/udgiv/publications/2018/10/978-87-93614-84-7.pdf","accessed":"2026-03-08","year":2019,"notes":"Danish EPA (2018): tested commercial slime kits available in Danish market; measured urinary boron in children using slime; found exceedance of EU tolerable daily intake for boron in regular slime users; basis for EU toy safety directive amendment. UK Chemical Awareness Group (2019): corroborating assessment of urinary boron elevation in UK children using commercial slime; recommended the EU boron migration limit as precautionary measure."},{"id":"src_002","type":"regulatory","title":"ECHA — Boric acid and disodium tetraborate SVHC classification (CMR Cat. 1B Repr.); EU Toy Safety Directive amendment — boron migration limit (effective January 2021)","url":"https://echa.europa.eu/substance-information/-/substanceinfo/100.030.394","accessed":"2026-03-08","year":2021,"notes":"ECHA: boric acid classified Repr. Cat. 1B (H360FD — may damage fertility, may damage the unborn child); borax (disodium tetraborate) same classification; both on SVHC candidate list under REACH. EU Toy Safety Directive amendment: boron migration limit ≤1500 mg/kg for materials that can be modelled or slime materials; effective January 2021; legal basis for EU market compliance testing"},{"id":"src_003","type":"regulatory","title":"CPSC — ASTM F963 Toy Safety Standard; CPSC general toy safety regulations (16 CFR Part 1500); FDA status of borax in food and consumer products","url":"https://www.cpsc.gov/Business--Manufacturing/Business-Education/Business-Guidance/Toy-Safety","accessed":"2026-03-08","year":2024,"notes":"CPSC ASTM F963 toy safety standard: no boron migration limit; covers lead, arsenic, antimony, barium, cadmium, chromium, selenium, mercury but not boron. CPSC has not initiated rulemaking on boric acid in toys as of 2026. FDA: borax not GRAS as direct food additive; no toy/play material regulatory action. US regulatory gap documented relative to EU Toy Safety Directive boron limit."}],"meta":{"schema_version":"4.0.0","last_updated":"2026-03-25","timestamp":"2026-05-01T19:32:06.104Z"}}