Compounds in this group can cause a wide range of effects on human health and have been linked to skin, lung, bladder, liver and stomach cancers. There are also results available indicating genetic, reproductive and developmental effects.
Polyaromatic hydrocarbons (PAHs) have moderate to acute toxicity to aquatic life and birds. Adverse effects on these organisms include tumours, impaired reproduction and foetal development, and effects on the immune system.
Bioaccumulation has also been shown in terrestrial invertebrates.
Function and use
PAHs appear primarily as unintended impurities formed in industrial processes such as in the cracking of petroleum, or in coal-based oils and smaller molecules that are used in the production of a wide range of materials like rubber and plastics.
Other aromatics included in this group, like benzene, are widely used as solvents or starting materials in the chemical industry and are also found as by-products in consumer products as they are common residues/impurities in materials with fossil origin.
The main function of furan is as a solvent or building block in chemical synthesis.
Resorcinol is mainly used as a building block, primarily in the production of polymers.
Areas of application
Oils used as softeners or extenders in rubber and plastic may be contaminated with PAHs. PAHs may also be formed by thermal decomposition of recycled materials and may be present as impurities in carbon black pigments and dyestuff.
Naphthalene is often present as an impurity from raw materials used in the production of textile dye dispersing agents and may thus be found in textiles.
Furan is mainly used as a solvent in lacquers, while resorcinol is primarily used in the rubber industry and is also commonly used in hair dyes and acne medication.
Many aromatics are restricted in legislation around the world, including in the EU. REACH annex XVII restricts eight PAHs in all products, and additional PAHs are included in POPs regarding emissions and effluents. Many apparel and footwear brands have strongly restricted the presence of this group of compounds in their products.
Benzene is also restricted in the EU (REACH Annex XVII) and in the US. Furan is listed in the REACH Candidate List and resorcinol is under investigation regarding endocrine-disruption properties.
The most efficient way to phase out the presence of aromatics would be to substitute to materials not based on fossil substances. A reduction of the of PAHs present in products could also be achieved by using rubber and plastic materials without extender oils.
Some alternative extender oils with reduced PAH content are available on the market, for example Treated Distillate Aromatic Extract (TDAE) and Mild Extracted Solvate (MES). There are various brands and applications.