Substance groups

Substances within a substance group are often similar in structure and can often fulfill the same chemical function and have the same areas of use. The substances may also have similar inherent properties and display similar toxicological properties. This is good to consider regarding substitution. Replacing a hazardous substance with another within the same substance group can be problematic.

Alkylphenols are organic compounds consisting of hydrocarbon chains bound to a phenol. Most frequently a single alkyl chain is linked to the 4-position of the phenol. Alkylphenols are for example used as antioxidants, but also within industry as monomer and to produce alkylphenol ethoxylates. Alkylphenol ethoxylates are for example used in detergents, lubricating oil, and paint.
Many alkylphenols and alkylphenol ethoxylates are toxic to aquatic organisms. Some of them do not easily degrade and may have endocrine disrupting effects. The substance groups in PRIO include monosubstituted derivatives where, among others, nonylphenol and nonylphenol ethoxylate are included. Several alkylphenols and alkylphenol ethoxylates are included on the Candidate List.

Azo dyes are used in dyeing textile fibers, primarily cotton but also silk, wool, viscose and synthetic fibers. Azo dyes can degrade into a group of substances called aromatic amines. These substances can be carcinogenic, interfere with fertility or be allergenic. Azo dyes that can degrade into carcinogenic arylamines are prohibited for use in textiles. Dispersion dyes, which are used to dye synthetic fibers such as polyamide and polyester, are associated with allergenic properties.


Bisphenols such as bisphenol A (BPA) are used, among other things, as intermediates in the production of epoxy and polycarbonate plastics. Epoxy is used in electronics, building materials, glue, as a protective varnish in cans and soda cans, and in the renovation of water and sewer pipes. One use of polycarbonate plastic is in the manufacture of plastic bottles. Other structurally similar bisphenols can potentially replace BPA in several of these applications. Bisphenols can also have other uses such as antioxidants or flame retardants where the technical function depends on the chemical structure.

Many bisphenols are, or are suspected to be, endocrine disruptors. The substance group in PRIO includes BPA and additional substances structurally similar to BPA (see generic structure below). The phenol moieties of the bisphenol generic structure can be unsubstituted or alternatively substituted with alkyl groups or halogens, and the bridge between the phenols is normally -CH2-, -CR2- or -SO2-. The group also includes salts of bisphenols. There may be additional structurally similar substances in PRIO that resemble bisphenols but are not covered by the substance group definition.

Generic structure for substances in the bisphenols substance group

Flame retardants are used to delay or prevent a material from starting to burn. Textiles and furniture in public environments, protective clothing, rubber cables, insulation materials and electrical and electronic equipment are examples of articles that can be flame retarded. Certain flame retardants are hazardous to health and the environment, and some of these are endocrine disruptors. There are several hundred different flame retardants, of which about 70 contain bromine. Several of the most dangerous flame retardants are banned in, for example, electronics. Flame retardants can leak out when articles are manufactured, used and when they are destructed. Brominated flame retardants remain in nature for a long time, accumulate in organisms and are toxic. They can be transported long distances in the air. We can ingest flame retardants, for example through food, mainly fish. Many flame retardants are found in the dust indoors, but by cleaning and ventilating, the amount is reduced.

Chlorinated paraffins are hydrocarbons with a straight carbon chain that consist of 10–30 carbon atoms and where 40–70 percent of the hydrogen atoms are exchanged for chlorine atoms.

Chlorinated paraffins are divided into short-, medium-, and long-chain depending on the length of the carbon chain. Short-chain chlorinated paraffins have 10–13 carbon atoms, medium-chain chlorinated paraffins have 14–17 carbon atoms, and long-chain chlorinated paraffins have more than 17 carbon atoms.

Chlorinated paraffins have a wide range of uses. They are, for instance, used in cutting fluids for metal and as plasticisers and flame retardants in a variety of articles and products, such as PVC cable, foam sealants and textiles. They are also used in, among other things, refrigerants and lubricants in the metalworking industry and as additives in sealants, paints, plastics and rubber. Chlorinated paraffins are stable, persistent and have negative effects on health and the environment. Short- and medium-chain chlorinated paraffins are highly toxic to aquatic organisms and because they are bioaccumulative, they can cause long-term adverse effects. New research data indicate that also long-chain chlorinated paraffins are bioaccumulative.

Chlorinated solvents are hydrocarbons with one to two carbon atoms, where several hydrogen atoms are exchanged for chlorine atoms.

Chlorinated solvents have been used extensively in Swedish industry. Among other things as a solvent and extraction agent in the engineering industry, chemical engineering industry, electronics industry, and in dry cleaning. However, the use of chlorinated solvents has decreased sharply since the bans entered into force and the requirement for exemptions was introduced. Due to their fatdissolving properties, chlorinated solvents are used as degreasing agents for metals, among other things, and as drycleaning fluids. These substances are generally harmful to health. In the environment, they are harmful to aquatic organisms.

Chlorofluorocarbons are hydrocarbons that contain one or two carbon atoms and where the hydrogen atoms have been replaced by chlorine and / or fluorine. They are mainly used as refrigerants in refrigeration systems, are volatile and stable gases but they also contribute to deplete the ozone layer and are therefore banned both by international agreements and at national level.

Hydrofluorocarbons (HFCs), are synthetically produced fluorinated gases that were developed as a substitute for the ozonedepleting chlorofluorocarbons but which are also very potent greenhouse gases and contribute to global warming.

Read more about the regulations of greenhouse gases (in Swedish only).

Complex hydrocarbons are produced by refining crude oil and coal tar. Complex hydrocarbons are mixtures of various organic substances and are often classified as carcinogenic if, for example, they contain substances such as benzene and polyaromatic hydrocarbons (PAH). Most complex hydrocarbons are considered as phase-out substances in the PRIO tool.

Complex hydrocarbons can be treated chemically so that the concentrations of the carcinogenic constituents are reduced. When the concentrations of these substances are below certain limit values, the complex hydrocarbon should no longer be classified as carcinogenic. On the market, most complex hydrocarbons are treated and should therefore not be regarded as phase-out substances. This is the reason why many substances belonging to the group complex hydrocarbons in PRIO are followed by the text “Please note! Not always valid”.

Dioxins and dibenzofurans are chlorinated environmental toxins that are sometimes referred to jointly as "dioxins". The complete names are polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) respectively.

Dioxins and dibenzofurans are formed during the combustion of organic matter together with materials that contain chlorine e.g. PVC plastic. They do not have any areas of use but can be formed as contaminants in the manufacturing of other chlorinated organic substances. The number of possible substances that can be formed is 210 and 17 of them are regarded as particularly toxic. The most toxic is 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).

Dioxins and dibenzofurans are among the substances included in the Stockholm Convention on Persistent Organic Pollutants, so-called POPs.

Read more about dioxins and dibenzofurans on the Swedish Environmental Protection Agency's website (in Swedish only). External link, opens in new window.

High-aromatic oils (HA oils) are a residual product that is formed during the manufacturing of, for example, lubricating oils. They are mostly used in rubber manufacturing and are present in for example car tires to make the tires soft. HA oil contains large amounts of aromatic and polycyclic aromatic hydrocarbons (PAHs), several of which are classified as carcinogenic.

Isocyanates are used as a raw material in the production of polyurethane (PUR) which is used in plastics and as a binder in adhesives, paints and varnishes. In general, isocyanates can cause allergies by skin contact or inhalation and damage to the respiratory system by inhalation of vapors or aerosols. Some isocyanates can cause cancer. Some are also classified as harmful to the environment, as they are toxic to aquatic organisms. Foremost, isocyanates are a work environment problem and there are regulations on work with thermosetting plastics containing isocyanates.

Read more about isocyanates on the Swedish Work Environment Authority's website. External link, opens in new window.

Many metal compounds in PRIO are classified as hazardous to the enironment, e.g. several copper and zinc compounds. The toxicity of the metal compound will depend on the intrinsic properties of the metal ion and to what extent it is released to the environment. Some substance groups, for example lead, cadmium, mercury and their compounds, have also demonstrated negative effects on human health.

Groups of metals and metal compounds in PRIO:

  • Arsenic compounds
  • Lead and lead compounds
  • Cadmium and cadmium compounds
  • Cobalt compounds
  • Copper compounds
  • Chromium compounds
  • Mercury and mercury compounds
  • Nickel compounds
  • Silver compounds
  • Organotin compounds
  • Zinc compounds

PFAS (Per- and polyfluoroalkyl substances) are used, among other things, to create water, grease and dirt-repellent surfaces. They are used, for example, in fire-fighting foam, textiles, impregnating agents, floor wax and ski wax. In the PRIO database there are almost 11 000 PFAS listed. All PFAS substances in PRIO fulfils the OECD PFAS definition (2021). These substances are amongst the most resistant toward degradation in nature. Studies show that the levels of these substances are increasing in seals, reindeer, and polar bears in the Arctic. They have also been found in low levels in the blood of humans. It is mainly through contaminated drinking water and food like fish, that humans ingest PFAS.

Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are among the most studied substances in the PFAS group and also the most regulated ones. The substance groups of PFOS and PFOA include their corresponding acids and salts as well as such substances that can be degraded to PFOS and PFOA. The substance groups are therefore called perfluorooctanesulfonic acid (PFOS) / perfluorooctanoic acid (PFOA) and its derivatives. The members belonging to the PFOS / PFOA groups in PRIO are based on indicative lists in the Stockholm Convention and REACH as well as on assessments by the Swedish Chemicals Agency. There may be additional PFAS substances covered by each substance group.

The substance group of Perfluorohexanesulfonic acid (PFHxS) include the acid form and its corresponding salts, as well as substances that can degrade to PFHxS. The substance group is therefore called Perfluorohexanesulfonic acid (PFHxS) and its derivatives. The members belonging to the PFHxS group in PRIO is based on the indicative list in the Stockholm Convention (UNEP/POPS/POPRC.15/INF/9) and ECHA's example list of PFHxS substances in the POPs Regulation (The Stockholm Convention is implemented in EU legislation through the POPs Regulation). There may be additional PFAS substances covered by this substance group.

Read more about PFAS.

Phthalates are a group of substances that can be used to make plastics and rubber soft and flexible. They can be found in many different types of plastic and rubber products, such as exercise mats, bathroom mats, garden hoses, artificial leather, plastic floors, electric cables, and rubber prints on clothes. There can also be phthalates in paint and glue. The substances can leak out of the materials and be absorbed directly by the skin or enter our bodies indirectly for example via food. The substances have been found in analyses of blood, breast milk and urine. Not all phthalates are harmful, but some can affect the development of the testicles and make it more difficult to have children. Some phthalates are, or are suspected to be, endocrine disruptors. Several phthalates are restricted in toys and childcare articles and in consumer products. The substance group in PRIO includes organic phthalates (phthalic acid esters).

Polychlorinated biphenyls (PCBs) is a collective name for a group of substances that contain a biphenyl, or two aromatic rings, with varying numbers of chlorine atoms on each ring. PCBs are fat-soluble, toxic and persistent substances that are stored in the adipose tissue of living things or in the environment. They have mainly been used as insulation and lubricating oil in capacitors as well as in transformers, sealants, paint, self-copying paper, etc. All use of PCBs in new products was banned in 1978. The regulations to stop the spread of PCBs are found in Regulation (2007:19) on PCBs etc. For PCB products that are waste, there are also provisions in the waste regulation and the waste incineration regulation.

Read more about PCBs on the Swedish Environmental Protection Agency's website (in Swedish only). External link, opens in new window.

PAHs consist of two or more fused aromatic rings and together form a group of several hundred substances where benzene is the simplest aromatic hydrocarbon. PAHs are formed when carbon or hydrocarbons, such as various oils, are heated without there being enough oxygen to provide complete combustion to carbon dioxide. This can take place in industrial processes such as cracking of petroleum, or in internal combustion engines in cars. They are also formed when grilling food. PAHs are the largest group of carcinogens we know today.

Last published 21 May 2024