Fire Retardants

Regulations on furniture flammability

• 1977 - Woolworths Manchester Burned down → introduced flame retardants

  • polyurethane foam in stuffing was highly flammable

• Reduced fire related deaths

• UK (and a few other EU countries) have regulations covering furniture flammability

  • GPSD → General Product Safety Directive

  • EN Standards → especially EN 1021 and EN 597

Flame retardants

• example

• mechanism

• issues

• Bromodiphenyl ether (BDE-47)

• Halogenated compound which thermally decomposes to release bromine free radicals

• halogen free radicals can then quench radicals which sustain combustion (H, OH and O free radicals)

  • This stops the fire

• Poor biodegradability → bromine not found in environment so not used naturally or digested by enzymes

• Lipophilic → not water soluble

  • can cross BBB and accumulate in body fat

  • LogP ~ 6

Forever chemicals

• Persistent organic pollutants (POP)

• Bioaccumulates → persist in the environment for long periods of time

• Half-life of days/years in humans

• Often contain halogens (Br and Cl)

• Present from poles to equator

  • In natural environments (especially water)

  • in organisms (mammals, fish, birds) → gets into food chain

  • in people → found in 100% of 298 human milk samples (Canada. 2008-11)

  • in buildings and vehicles

• Includes flame retardants

Half-life of brominated compounds

• Half-life of BDE-47 is around 664 days (1.8 years)

  • time for concentration to half

• This is the time for elimination in the absence of further uptake

• follows exponential decay

• time for elimination varies with diet and metabolism

• decay from systemic circulation results in continuous exposure to the nervous system

• Can be much longer in other compounds

BDE-47 systematic reviews and meta-analysis

• how

• findings

• collation of data from several studies, with adjustment for major confounders (maternal education, income, smoking, alcohol, home environment, breast feeding)

• BDE-47 in maternal blood, child blood and breast milk measured

  • Blood BDE-47 up to 1470ng/g of lipid

  • Breast milk BDE-47 up to 200mg/g lipid

• BDE-47 in infants is associated with decrements in motor development, cognitive development and attention-related behaviours

  • IQ decreased by 3.7

  • Prenatal exposure is the strongest predictor

  • limited association with ADHD

• Exposure begins in-utero by breast feeding

Mechanisms of BDE-47 in neurobiology

• studied by in-vitro and in-vivo studies

• looked at Cerebellar granule neurones involved in motor learning, coordination and sensory processing

• effects on mouse neurones:

  • alters signal transduction

  • oxidative stress

  • apoptosis

• Increases reactive oxygen species (ROS) and reactive carbonyls

• decrease cell viability

• increase apoptotic markers (Caspase-3)

Limitations of using animal studies in BDE-47 studies

• In-vivo duration and dosage

  • micromolar over days

  • doesn’t represent human exposure

• In-vivo tissue concentration

  • hard to compare to humans as they are an order larger

• studies are post-natal not in-utero

• No behavioural follow up → learning, memory, motor function

• ROS production is a causal factor in the neuronal dysfunction caused by BDE-47

International legislation and mitigation for flame retardands

• mitigation and legislation consensus published in Environmental International in 2023

  • UK has highest use

  • unsure of whether and to what extent flame retardants contribute to fire safety

  • flawed tests for fire safety (eg. ignition test)

  • recommendations:

    • minimise use

    • use less combustible materials

    • evaluate fire risks and therefore need for flame retardants

    • promote culture which considers environmental impact

• implications of global health

• prognosis for future generations

UK legislation (2025)

• PBDE regulations (poly-BDE)

  • tetra-, penta-, hexa-, hepta- and deca-BDEs

  • manufacture and sales banned

• Waste containing PBDEs

  • destroy or irreversibly transform

• Electronics

  • Max 0.1% PBDE content

• Water/envrionment

  • classified as priority hazzardous pollutants

  • ongoing surevilance

• Waste mannagement

  • no recycling avove POP limits

  • mandatory destruction by incineration for water exceeding threshold

  • strict control of old electronics, foams, textiles and plastics