Its major uses are in the production of heat-transfer fluids (for example, as an intermediate for polychlorinated biphenyls) and dye carriers for textile dyeing. Lesser uses are as a mould retardant in citrus fruit wrappers, in formation of plastics, optical brighteners, and hydraulic fluids.
Substance name: Biphenyl (1,1-biphenyl)
CASR number: 92-52-4
Molecular formula: C12H10
Synonyms: phenylbenzene; 1,1'-biphenyl; 1,1'-diphenyl; diphenyl; bibenzene; lemonene; phenador-x; phph; xenene
Biphenyl is a colourless to yellow solid with a pleasant odour. It is soluble in alcohol, ether, benzene, methanol, carbon tetrachloride, carbon disulfide, and most organic solvents. It is very slightly soluble in water.
Formula mass: 154.21
Melting Point: 70°C
Boiling Point: 255°C
Specific Gravity: 0.991
Vapour Density: 5.31
1 ppm = 6.3 mg/m3
Biphenyl is one of the most thermally stable of all organic compounds. It is combustible at high temperatures producing carbon dioxide and water when combustion is complete. Partial combustion produces carbon monoxide, smoke, soot, and low molecular weight hydrocarbons.
The National Pollutant Inventory (NPI) holds data for all sources of biphenyl emissions in Australia.
Workers exposed to biphenyl fumes for short periods of time have experienced nausea, vomiting, irritation of the eyes and respiratory tract, and bronchitis. These acute effects are not likely to occur at levels of biphenyl that are normally found in the environment.
Breathing small amounts of biphenyl over long periods has caused damage to the liver and nervous system of exposed workers. Other human health effects associated with exposure to small amounts of biphenyl over long periods are not known. Laboratory studies show that repeat exposure to large amounts of biphenyl by ingestion damages the kidney and blood, and reduces growth and life expectancy of animals. Limited evidence suggests that repeat exposure to biphenyl dust adversely affects the respiratory tract of laboratory animals.
Entering the body
The substance can be absorbed into the body by inhalation and by ingestion.
You may be exposed to biphenyl if you live near an industrial site where biphenyl is used, or a waste dump where it has been discarded. At these sites, biphenyl may be carried in the air on dust particles. If you work in an industry that produces the chemical unintentionally as a by-product or uses biphenyl, you may also be exposed to biphenyl particles or dust particles that carry biphenyl and possibly get it on your skin.
Exposure to biphenyl can occur through eating citrus fruits that have been wrapped in paper impregnated with biphenyl.
Exposure to biphenyl can also occur through contact with biphenyl-contaminated soil, dust particles, or industrial releases into the environment.
Workplace exposure standards
Safe Work Australia sets the workplace exposure standard for biphenyl through the workplace exposure standards for airborne contaminants:
- Maximum eight hour time weighted average (TWA): 0.2 parts per million (1.3 mg/m3)
These standards are only appropriate for use in workplaces and are not limited to any specific industry or operation. Make sure you understand how to interpret the standards before you use them.
Drinking water guidelines
There is no guideline for biphenyl in the Australian Drinking Water Guidelines.
Biphenyl has high acute toxicity, but low chronic toxicity, to aquatic life. Biphenyl is expected to be non-toxic to terrestrial organisms at levels that are normally found in the environment.
Entering the environment
Volatilisation and sorption are important in the transport of biphenyl in water. As it is a solid that binds to soil, biphenyl will only move slowly through the ground and enter groundwater. The half-life of biphenyl in water is up to about 20 days.
Plants and animals may store small amounts of biphenyl.
About 59% of biphenyl will eventually end up in air; about 15.6% will end up in water; and the rest will be divided about equally between terrestrial soils and aquatic sediments.
Where it ends up
Biphenyl dissolves poorly when mixed with water. Most releases of biphenyl are to air. In air, biphenyl breaks down to other chemicals or settles as dry deposits to water or land. Biphenyl attaches to solid material in water. Microorganisms living in water and in soil break down biphenyl to other chemicals.
The dominant tropospheric loss process for biphenyl is reaction with the photochemically produced hydroxyl (OH) radical. The calculated half-life biphenyl due to reaction with the OH radical is estimated to be 1.4 days. The products observed are 2-hydroxybiphenyl and, in much lesser amounts, 3- and 4-hydroxybiphenyl, and 3-nitrobiphenyl.
No national guidelines.
Releases from industries producing, using, or handling biphenyl, or where it is used as a heat transfer agent (for example, electrical transformers).
Diffuse sources, and industry sources included in diffuse emissions data
Biphenyl enters the aquatic environment in wastewater effluents from textile mills that use it as a dye carrier; from industrial processes; and from leaking heat exchangers.
Biphenyl is released to the atmosphere as a fume during its use as a heat transfer fluid and, to a lesser extent, by volatilisation from soil and water.
It occurs naturally in trace amounts, mostly in crude oil.
Where used as a mould retardant in citrus fruit wrappers, in formation of plastics, optical brighteners, and hydraulic fluids.
No consumer products should intentionally contain biphenyl. However, it may be found as a contaminant in some foods, and possibly in dyed products such as textiles.
Sources used in preparing this information
- Australian and New Zealand Environment and Conservation Council (ANZECC) (1992), Australian Water Quality Guidelines for Fresh and Marine Waters.
- CalEPA Air Resources Board Toxic Air Contaminant Summary (accessed, June 1999)
- ChemFinder WebServer Project (1995) (accessed, June 1999)
- Environmental Defense Fund - Summary, Uses, Consumer Products, Rank (industrial, by quantity) (accessed, June 1999)
- IPCS International Chemical Safety Card (accessed, June 1999)
- Meagher, D (1991), The Macmillan Dictionary of The Australian Environment, Macmillan Education Australia Pty Ltd.
- National Environment Protection Council (1998), National Environment Protection Measure for the National Pollutant Inventory. (accessed, March, 1999)
- Richardson, M (1992), Dictionary of Substances and their Effects, Royal Society of Chemistry, Clays Ltd, England.
- Sittig, M (1991), Handbook of Toxic and Hazardous Chemicals and Carcinogens, 3rd edition, Noyes Publications, USA.
- Technical Advisory Panel (1999), Final Report to the National Environment Protection Council.
- USA National Toxicology Program Health and Safety Information Sheet (accessed, June 1999)
- US Department of Health and Human Services (1990), NIOSH Pocket Guide to Chemical Hazards, Publication No. 90-117.
- USEPA Health Effects Notebook for Hazardous Air Pollutants (accessed, June 1999)
- USEPA Integrated Risk Information System Report (accessed, June 1999)
- USEPA Office of Pollution Prevention and Toxics Chemical Facts (accessed, June 1999)
- USEPA Toxic Release Inventory Fact Sheet (accessed, June 1999)
- Safe Work Australia, Workplace exposure standards for airborne contaminants, accessed June 2021.
- National Health and Medical Research Council (NHMRC), Australian Drinking Water Guidelines (2011) - Updated October 2017, accessed May 2018