Dibutyl phthalate (DBP) is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

phthalate Phthalates ( ), or phthalate esters, are esters of phthalic acid. They are mainly used as plasticizers, i.e., substances added to plastics to increase their flexibility, transparency, durability, and longevity. They are used primarily to soften ...

which is commonly used as a

plasticizer A plasticizer ( UK: plasticiser) is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and/or to decrease friction during its handling in manufacture. Plasticizer ...

because of its low toxicity and wide liquid range. With the

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

C₆H₄(CO₂C₄H₉)₂, it is a colorless oil, although impurities often render commercial samples yellow.Peter M. Lorz, Friedrich K. Towae, Walter Enke, Rudolf Jäckh, Naresh Bhargava, Wolfgang Hillesheim "Phthalic Acid and Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry, 2007, Wiley-VCH, Weinheim. Dibutyl phthalate has high

dielectric constant The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insul ...

Production and use

DBP is produced by the reaction of ''n''-butanol with

phthalic anhydride Phthalic anhydride is the organic compound with the formula C6H4(CO)2O. It is the anhydride of phthalic acid. Phthalic anhydride is a principal commercial form of phthalic acid. It was the first anhydride of a dicarboxylic acid to be used commer ...

. DBP is an important plasticizer that enhances the utility of some major engineering plastics, such as PVC. Such modified PVC is widely used in plumbing for carrying sewage and other corrosive materials.

Degradation

Hydrolysis of DBP leads to

phthalic acid In organic chemistry, phthalic acid is an aromatic dicarboxylic acid, with formula and structure . Although phthalic acid is of modest commercial importance, the closely related derivative phthalic anhydride is a commodity chemical produced on ...

and

1-butanol 1-Butanol, also known as butan-1-ol or ''n''-butanol, is a primary alcohol with the chemical formula C4H9OH and a linear structure. Isomers of 1-butanol are isobutanol, butan-2-ol and ''tert''-butanol. The unmodified term butanol usually refers ...

Monobutyl phthalate Monobutyl phthalate (MBP) is an organic compound with the condensed structural formula CH3(CH2)3OOCC6H4COOH. It is a white solid that features both an butyl ester group and a carboxylic acid group. It is the major metabolite of dibutyl phthalate. ...

(MBP) is its major metabolite.

Biodegradation

Biodegradation Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting. Composting is a human-driven process in which biodegrada ...

by microorganisms represents one route for remediation of DBP. For example, ''

Enterobacter ''Enterobacter'' is a genus of common Gram-negative, Facultative anaerobic organism, facultatively anaerobic, bacillus (shape), rod-shaped, non-spore-forming bacteria of the family Enterobacteriaceae. Cultures are found in soil, water, sewage, ...

'' species can biodegrade municipal solid waste—where the DBP concentration can be observed at 1500 ppm—with a

half-life Half-life is a mathematical and scientific description of exponential or gradual decay. Half-life, half life or halflife may also refer to: Film * Half-Life (film), ''Half-Life'' (film), a 2008 independent film by Jennifer Phang * ''Half Life: ...

of 2–3 hours. In contrast, the same species can break down 100% of

dimethyl phthalate Dimethyl phthalate (DMP) is an organic compound and phthalate ester. it is a colourless and oily liquid that is soluble in organic solvents, but which is only poorly soluble in water (~4 g/L). It is used in a variety of products and is most commo ...

after a span of six days. The white rot fungus ''

Polyporus brumalis ''Lentinus brumalis'' is an inedible species of fungus in the family Polyporaceae. Its common name is the winter polypore. The epithet ''brumalis'' means "occurring in the winter", describing how this species tends to fruit during winter. It caus ...

'' degrades DBP. DBP is leached from landfills.

Physical properties relevant to biodegradation

As reflected by its

octanol-water partition coefficient The ''n''-octanol-water partition coefficient, ''K''ow is a partition coefficient for the two-phase system consisting of ''n''-octanol and water. ''K''ow is also frequently referred to by the symbol P, especially in the English literature. It is a ...

of around 4, it is lipophilic, which means that it is not readily mobilized (dissolved by) water. Nonetheless, dissolved organic compounds (DOC) increase its mobility in

landfill A landfill is a site for the disposal of waste materials. It is the oldest and most common form of waste disposal, although the systematic burial of waste with daily, intermediate and final covers only began in the 1940s. In the past, waste was ...

s. DBP has a low

vapor pressure Vapor pressure or equilibrium vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The equilibrium vapor pressure is an indicat ...

of 2.67 x 10⁻³ Pa. Thus DBP does not evaporate readily (hence its utility as a plasticizer). The Henry's Law constant is 8.83 x 10⁻⁷ atm-m³/mol.

Legislation

DBP is regarded as an

endocrine disruptor Endocrine disruptors, sometimes also referred to as hormonally active agents, endocrine disrupting chemicals, or endocrine disrupting compounds are chemicals that can interfere with endocrine (or hormonal) systems. These disruptions can cause ...

European Union

The use of this substance in cosmetics, including nail polishes, is banned in the

European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are Geography of the European Union, located primarily in Europe. The u ...

under Directive 76/768/EEC 1976. The use of DBP has been restricted in the European Union for use in children's toys since 1999. An EU Risk Assessment has been conducted on DBP and the outcome has now been published in the EU Official Journal. To eliminate a potential risk to plants in the vicinity of processing sites and workers through inhalation, measures are to be taken within the framework of the IPPC Directive (96/61/EC) and the Occupational Exposure Directive (98/24/EC) Also includes the 2004 addendum. Based on urine samples from people of different ages, the European Commission

Scientific Committee on Health and Environmental Risks The Scientific Committee on Health and Environmental Risks (SCHER) is one of the independent scientific committees managed by the Directorate-General for Health and Consumer Protection of the European Commission, which provide scientific advice to ...

(SCHER) concluded that total exposures to DBP should be further reduced. Under

Directive 2011/65/EU revision 2015/863,Commission Delegated Directive (EU) 2015/863 of 31 March 2015 amending Annex II to Directive 2011/65/EU of the European Parliament and of the Council as regards the list of restricted substances
/ref> DBP is limited to max 1000 ppm concentration in any homogenous material.

United States

Dibutyl phthalate (DBP) is one of the six

esters found on the Priority Pollutant List, which consists of pollutants regulated by the

United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an independent agency of the United States government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it began operation on De ...

(U.S. EPA). DBP was added to the

California Proposition 65 (1986) Proposition 65 (formally titled The Safe Drinking Water and Toxic Enforcement Act of 1986, and also referred to as Prop 65) is a California law passed by direct voter initiative in 1986 by a 63%–37% vote. Its goals are to protect drinking wate ...

list of suspected teratogens in November 2006. It is a suspected

. It was used in many consumer products, e.g.,

nail polish Nail polish (also known as nail varnish in British English or nail enamel) is a lacquer that can be applied to the human Nail (anatomy), fingernails or toenails to decorate and protect the nail plates. The formula has been revised repeatedly t ...

, but such usages has declined since around 2006. It was banned in children's toys, in concentrations of 1000 ppm or greater, under section 108 of the

Consumer Product Safety Improvement Act The Consumer Product Safety Improvement Act of 2008 (CPSIA) is a United States law signed on August 14, 2008 by President George W. Bush. The law increased the budget of the Consumer Product Safety Commission (CPSC), imposes new testing and docum ...

of 2008 (CPSIA).

Safety

Phthalates are noncorrosive with low acute toxicity.

References

External links

*
Dibutyl Phthalate and Cosmetics

Hazardous substance fact sheet

* ttps://www.cdc.gov/niosh/npg/npgd0187.html CDC - NIOSH Pocket Guide to Chemical Hazards {{DEFAULTSORT:Dibutyl Phthalate Plasticizers Phthalate esters Endocrine disruptors Butyl esters