Glossary of terms

A

Acetylcholinesterase inhibitor

An enzyme or substance that blocks acetylcholinesterase, the enzyme responsible for breaking down the neurotransmitter acetylcholine after nerve signals are transmitted. Without this enzyme, acetylcholine accumulates at nerve junctions, causing continuous nerve stimulation. Organophosphate pesticides work through this mechanism, which is why they are also related to nerve agents developed for chemical warfare.

B

Bioaccumulation

The process by which a chemical builds up in a living organism faster than it can be broken down or excreted. Bioaccumulation is particularly relevant for fat-soluble chemicals like PFAS, PBDEs and heavy metals, which concentrate in fatty tissues over a lifetime of exposure. The higher up the food chain an organism is, the higher its body burden tends to be, a related phenomenon called biomagnification.

Biomonitoring

The direct measurement of chemicals or their metabolites in human tissue, blood, urine or breast milk. Biomonitoring studies by agencies including the CDC (through its NHANES programme) and European equivalents provide the most accurate picture of actual human chemical exposure at a population level. Results consistently find industrial chemicals in virtually all people tested, regardless of lifestyle.

BPA (Bisphenol A)

An industrial chemical used since the 1960s to make hard polycarbonate plastics and epoxy resins that line food and drink cans. BPA is an endocrine disruptor that mimics oestrogen and has been linked to reproductive harm, metabolic disruption and behavioural effects in developing children. Most countries have restricted its use in baby products, but BPA and its replacements remain common in food packaging and thermal paper.

BPS (Bisphenol S)

The most common replacement for BPA in plastics and coatings, introduced after public pressure led to BPA restrictions. BPS shows similar oestrogenic activity to BPA in laboratory research and may be more persistent in the environment. The switch from BPA to BPS is a textbook example of what toxicologists call regrettable substitution.

C

Carcinogen

A substance capable of causing cancer through cellular or genetic damage. Carcinogens are classified by the International Agency for Research on Cancer (IARC) into Group 1 (confirmed human carcinogens), Group 2A (probable), Group 2B (possible) and Group 3 (not classifiable). Many household chemicals fall into Group 2A or 2B, meaning evidence is substantial enough to warrant concern but human data are not yet conclusive.

Chelation

A medical process in which chelating agents are administered to bind heavy metals in the body and facilitate their excretion in urine. Chelation therapy is used for acute heavy metal poisoning, such as lead poisoning in children with very high blood levels. It is not appropriate or recommended for general environmental exposure reduction, and is not an alternative to reducing ongoing exposure.

Circadian rhythm

The approximately 24-hour biological cycle that regulates sleep, hormone production, metabolism, immune function and virtually every organ system. The circadian rhythm is set primarily by light exposure, particularly blue wavelengths (460 to 495nm) detected by specialised cells in the eye. Disruption of the circadian rhythm through light pollution, shift work or poor sleep habits is associated with increased risk of obesity, metabolic disease, mood disorders and certain cancers.

E

EDC (Endocrine Disrupting Chemical)

A chemical that interferes with the endocrine (hormone) system by mimicking hormones, blocking hormone receptors, or altering hormone production and metabolism. EDCs are particularly concerning because they can cause harm at very low doses, and sometimes at lower doses than higher ones, a phenomenon that confounds traditional toxicology risk assessment.

EFSA

The European Food Safety Authority, an independent EU agency that provides scientific advice on food and chemical safety to inform EU regulations. EFSA has published important risk assessments on PFAS, BPA, phthalates and other household chemicals. Its 2023 re-evaluation of BPA dramatically lowered the tolerable daily intake by a factor of 20,000.

Endocrine system

The network of glands and organs that produce, store and release hormones into the bloodstream to regulate bodily functions. Key components include the thyroid gland, adrenal glands, pituitary gland, ovaries and testes, and pancreas. The endocrine system controls growth, metabolism, reproduction, mood, sleep and immune response, making it a particularly sensitive target for chemical disruption.

EPA

The United States Environmental Protection Agency, the federal agency responsible for regulating environmental contaminants including chemicals in air, water, soil and consumer products. The EPA sets maximum contaminant levels for drinking water pollutants, conducts chemical risk assessments through its Integrated Risk Information System (IRIS), and can restrict or ban chemicals under the Toxic Substances Control Act (TSCA).

G

GOTS certification

The Global Organic Textile Standard, the gold standard certification for organic textiles covering the entire supply chain from farming to finished product. GOTS certification requires at least 70% organic fibres, prohibits hundreds of harmful chemicals in processing, and includes social and labour criteria. It is the most reliable way to verify that clothing and bedding is genuinely organic and free from harmful textile finishes.

H

Half-life

The time required for half of a substance to be eliminated from the body or environment. A chemical with a long biological half-life accumulates with repeated exposure. PFOS (a type of PFAS) has a human half-life of approximately 5 to 8 years; BPA has a half-life of around 6 hours; phthalates clear within 24 to 48 hours. Half-life determines how quickly body burden falls after reducing exposure.

Halogenated compound

A chemical compound containing one or more halogen atoms: fluorine, chlorine, bromine or iodine. Halogenated compounds are often highly stable and persistent in the environment because the carbon-halogen bond is very strong. PFAS are halogenated (fluorinated) compounds. PBDEs are brominated. Many of the most persistent environmental pollutants are halogenated.

I

IARC

The International Agency for Research on Cancer, a specialised cancer research agency of the World Health Organization. IARC evaluates and classifies potential human carcinogens, with its classifications (Group 1, 2A, 2B, 3) widely used by regulators and researchers globally. IARC classified formaldehyde as Group 1 (confirmed human carcinogen) in 2004 and is currently reviewing PFAS.

INCI (International Nomenclature Cosmetic Ingredient)

The standardised naming system used on cosmetic ingredient labels globally. INCI names are Latin-based and specific, unlike marketing terms. For example, the INCI name for vitamin E is tocopherol, for water is aqua, and synthetic fragrance appears simply as parfum. Reading the INCI list is the only reliable way to identify what is actually in a personal care product.

M

Microplastics

Plastic particles smaller than 5mm, ranging down to nanoplastics invisible to the naked eye. Microplastics originate from the breakdown of larger plastic items, from synthetic textile fibres released in washing, and from industrial processes. They are now found in virtually every environment on Earth and in human blood, lung tissue, breast milk, placenta and brain tissue. Health effects are an active area of research.

N

Nanoplastics

Plastic particles smaller than 1 micrometre (1000 nanometres), invisible to the naked eye and small enough to cross cell membranes and the blood-brain barrier. Nanoplastics form from the continued breakdown of microplastics and are more concerning than microplastics because of their ability to penetrate biological barriers. Detection methods for nanoplastics in human tissue are still being developed, making quantification challenging.

O

Off-gassing

The release of volatile organic compounds (VOCs) from solid or liquid materials into the surrounding air at room temperature. New furniture, flooring, paint, mattresses, electronic devices and many consumer products off-gas upon manufacture and continue doing so for weeks, months or years. The characteristic smell of a new car, new carpet or fresh paint is off-gassing.

Organophosphate

A class of synthetic compounds sharing a phosphate ester chemical structure, originally developed as nerve agents and later adapted as agricultural pesticides. Organophosphates inhibit acetylcholinesterase, disrupting nerve signal transmission. They degrade relatively quickly in the environment but leave residues on food. Chlorpyrifos, malathion and glyphosate adjuvants are common examples.

P

Paraben

A class of synthetic preservatives widely used in cosmetics, pharmaceuticals and food products to prevent bacterial and fungal growth. Parabens (methylparaben, propylparaben, butylparaben, ethylparaben) are absorbed through skin and act as weak oestrogen mimics. They have been detected in breast tumour tissue and are associated with reproductive disruption in epidemiological studies.

Persistent organic pollutant (POP)

A toxic chemical that resists environmental degradation, bioaccumulates in food chains and can travel long distances from its point of origin. POPs are regulated under the Stockholm Convention, an international treaty. Examples include PCBs, DDT, PBDEs and PFAS. They are detected in remote environments including Arctic ice and organisms that have never been near industrial activity.

PFAS

Per- and polyfluoroalkyl substances, a family of over 12,000 synthetic chemicals sharing an extremely strong carbon-fluorine bond. This bond makes PFAS essentially indestructible in the environment and the human body, earning them the name forever chemicals. PFAS are used in non-stick coatings, water-resistant treatments, food packaging and fire-fighting foam. Health effects include thyroid disruption, immune suppression, cancer and reproductive harm.

Photobiomodulation

The use of specific wavelengths of light, primarily red (630 to 700nm) and near-infrared (800 to 1100nm), to stimulate cellular energy production in mitochondria and produce therapeutic effects. Research has demonstrated benefits for wound healing, inflammation reduction, muscle recovery and cognitive function. The photobiomodulation benefits of near-infrared light are a secondary benefit of incandescent and halogen bulbs, which produce significant infrared radiation unlike LEDs.

Phthalate

A class of chemical plasticisers added to PVC and other plastics to make them soft and flexible, and used as solvents and fixatives in synthetic fragrance. Phthalates are endocrine disruptors that interfere with testosterone signalling and are associated with reproductive harm, neurodevelopmental effects and thyroid disruption. They are found in virtually all people tested in biomonitoring studies.

Precautionary principle

A regulatory approach that places the burden of proof on demonstrating safety rather than harm. Under the precautionary principle, a chemical should be restricted or prohibited if there is credible evidence of potential harm, even if causation is not conclusively established. The EU generally applies this principle more broadly than the US, which tends to require stronger evidence of harm before restricting chemicals.

R

REACH (EU regulation)

Registration, Evaluation, Authorisation and Restriction of Chemicals, the EU chemicals regulation framework in force since 2007. REACH requires manufacturers to register chemicals and demonstrate safety before placing them on the market, placing the burden of proof on industry rather than regulators. It has led to the restriction or phasing out of hundreds of substances of very high concern in European products.

Regrettable substitution

The pattern where a chemical of concern is replaced with a structurally similar chemical that turns out to have the same or similar problems. BPA replaced with BPS is a classic example. Penta-BDE flame retardants replaced with organophosphate flame retardants is another. Regrettable substitution occurs partly because regulatory frameworks assess chemicals individually rather than by chemical class.

S

SVHC (Substance of Very High Concern)

A classification under EU REACH for chemicals that are carcinogenic, mutagenic or toxic to reproduction (CMR), persistent bioaccumulative and toxic (PBT), or endocrine disrupting. SVHCs are placed on a candidate list and may be subject to authorisation requirements, meaning companies must apply for permission to continue using them and demonstrate no safer alternatives exist.

T

Trihalomethane (THM)

A class of disinfection byproducts formed when chlorine reacts with naturally occurring organic matter in water. The most common THMs are chloroform, bromodichloromethane, dibromochloromethane and bromoform. THMs are present in virtually all chlorinated tap water. Chloroform is classified as a possible human carcinogen by IARC. Exposure occurs through drinking, cooking and showering.

V

VOC (Volatile Organic Compound)

A chemical compound with a low boiling point that evaporates readily at room temperature, releasing into the air as a gas. VOCs include a wide range of compounds from natural (terpenes from plants) to synthetic (benzene from paint, formaldehyde from pressed wood). Indoor VOC concentrations are typically 2 to 5 times higher than outdoors, and can spike significantly higher when using paints, cleaning products or adhesives.