Overview


Nonylphenol (NP) and Nonylphenol Ethoxylates (NPE) are the most widely used members of the larger alkylphenol and alkylphenol ethoxylate family of non-ionic surfactants. They are produced in large volumes, with uses that lead to widespread release to the aquatic environment.

NP is persistent in the aquatic environment, moderately bioaccumulative, and extremely toxic to aquatic organisms. NP's main use is in the manufacture of NPEs. NPEs are used in a wide variety of industrial applications and consumer products. NPEs, though less toxic than NP, are also highly toxic to aquatic organisms, and in the environment degrade to more environmentally persistent NP. NP has also been detected in human breast milk, blood, and urine and is associated with reproductive and developmental effects in fish.

NPEs were once commonly used in household laundry detergents. EPA and the detergent manufacturers have cooperated to eliminate this use. However, NPEs are still widely used in large quantities in industrial laundry detergents and have some additional uses that lead to releases to water (#EPA, NP and NPE Action Plan).
Image: chemical structure of NPEs

Chemical Description


NP is a clear to pale yellow viscous liquid at room temperature with moderate water solubility and moderate vapor pressure. NPEs are clear to light orange oily liquids or waxy solids, and are considered to be chemically stable and unreactive. NPEs are manufactured by reacting NP with ethylene oxide (EO) under basic conditions. The degree of ethoxylation depends on the molar ratio of NP to EO. NPEs are hydrophilic ("water-attracting") at one end of the molecule and hydrophobic ("water-avoiding") at the opposite end. The hydrophilic "head" attracts water and the hydrophobic "tail" attracts poorly soluble substances, such as oils and greases (#EPA, NP and NPE Action Plan).

Uses


Nonylphenol ethoxylates (NPEs) are surfactants that have been in commerce for over 50 years. Products containing NPEs are used in many sectors, including textile processing, pulp and paper processing, paints, resins and protective coatings, oil and gas recovery, steel manufacturing, pest control products and power generation. A variety of cleaning products, degreasers and detergents are also available for institutional and domestic use. These products have numerous applications, including controlling deposits on machinery, cleaning equipment, and scouring fibres; as wetting and de-wetting agents; in dyeing and machine felt cleaning and conditioning; and in product finishing. NPEs have also been used in a wide range of consumer products, including cosmetics, cleaners, and paints.

The primary use of NP is as an intermediate in the manufacture of NPEs. NP may also be reacted to form tris(4-nonyl-phenyl) phosphite (TNPP), an antioxidant used to protect polymers such as rubber, vinyl, polyolefins, and polystyrenics. TNPP is also used as a stabilizer in plastic food packaging. Although it does contain residual NP, TNPP has been approved for this use by the Food and Drug Administration (FDA). FDA also lists NP as an indirect food contact substance. Barium and calcium salts of NP are used as heat stabilizers for polyvinyl chloride (PVC). NP is also used as a catalytic diluent in epoxy resins (#EPA, NP and NPE Action Plan).

Routes of Exposure and Metabolism


Nonylphenol ethoxylates can enter the body by inhalation of air containing nonylphenol ethoxylates, ingestion of contaminated food or water, or by dermal contact with nonylphenol ethoxylates or products containing nonylphenol ethoxylates (#SEPA).

When animals ingest NP, the absorption of nonylphenol from the gastrointestinal tract is initially rapid, and probably extensive. The major metabolic pathways are likely to involve glucuronide and sulphate conjugation. Nonylphenol is distributed widely throughout the body, with the highest concentration in fat. Available data on bioaccumulation potential from both animal and human studies are inconsistent and do not allow for conclusions on the bioaccumulation potential of NP. The major routes of excretion of NP are via the feces and urine (#WHO).

In the environment, the long-chain NPEs biodegrade relatively quickly to short-chain NPEs and NP, which are much more resistant to further degradation. When in water, NPEs can also undergo photo-induced degradation. In the atmosphere, NP will be degraded rapidly by hydroxyl radicals and is not expected to be persistent in air.

Health Effects


Acute Health Effects

There is little evidence for any significant effects of exposure to nonylphenol ethoxylates on human health. However, exposure to high levels of nonylphenol ethoxylates may cause irritation of the lungs, digestive system, skin and eyes (#SEPA).

Chronic Health Effects

Nonylphenol ethoxylates are thought to interfere with hormones in animals and may therefore interfere with the development and reproductive system in animals. They are listed as endocrine disrupting chemicals on the EU List (#PANNA).

The International Agency for Research on Cancer has not designated nonylphenol ethoxylates in terms of their carcinogenicity (#SEPA).

Environmental Health Effects


NPE is very toxic to fish and other water-dwelling organisms and is considered a hormone disrupting substance, mimicking estrogen. It degrades relatively readily in the environment to form the even more harmful nonylphenol (NP). Nonylphenol is not readily biodegradable and take months or even longer to degrade in surface waters or in soils and sediments (where it tends to be immobilized). Non-biological degradation is negligible. Bioconcentration and bioaccumulation is significant in water-dwelling organisms and birds, where it has been found in internal organs at between 10 and 1000 times greater than the surrounding environment. Nonylphenols are not broken down effectively in sewage treatment plants.

Because of the bioaccumulation and persistence of nonylphenol (the primary degradation product of NPE), it is possible that it could be transported significant distances, and so have a potentially global reach in its effects (#UK Environment Agency).

Precautions


Human exposure to NP and NPEs is thought to come primarily from cleaners, detergents, agricultural and indoor pesticides, cosmetics, hair dyes, and aquatic foods like shellfish and fish.

Regulations


The European Union has effectively eliminated use of NP/NPE in most industrial and product sectors and Canada has implemented a pollution prevention plan designed to drastically reduce use of NP/NPE (EPA).
In the future EPA is planning to :
1. To support and encourage the voluntary phase-out of NPEs in industrial laundry detergents. (This voluntary phase out has already begun, and has a target completion date of December 2013.)
2. Simultaneous proposals for a) a "significant new use" rule, requiring any company wanting to add NPEs to their cleaning and detergent products to notify the EPA in advance to allow for regulatory action, and b) a test rule for any use of NP and NPEs, requiring the development of information to assess the effects on human health and the environment.
3. Add NP and NPEs to the list of chemicals included in the Toxic Substances Control Act that "present or may present an unreasonable risk of injury to health or the environment."
4. Add NP and NPEs to the Toxics Release Inventory list.
5. Support and encourage the elimination of other uses of NP and NPEs, including instituting regulatory action, if needed (#CAS Lab).


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*Nonylphenol kills special reproductive cells in male rats by changing the cell's outside membrane.

*Evidence for the migration of steroidal estrogens through riverbed sediments

*[Environmental Estrogens Induce Mast Cell Degranulation and Enhance IgE-mediated Release of Allergic Mediators.|http://www.environmentalhealthnews.org/newscience/2007/2007-0401naritaetal.html]

*Vallombrosa Consensus Statement on Environmental contaminants and human fertility compromise.

*The contribution of hepatic steroid metabolism to serum estradiol and estriol concentrations in nonylphenol treated MMTVneu mice and its potential effects on breast cancer incidence and latency.

*Accurate Prediction of the Response of Freshwater Fish to a Mixture of Estrogenic Chemicals.

*Urinary Concentrations of Bisphenol A and 4-Nonylphenol in a Human Reference Population.

*Promoting insulin secretion in pancreatic islets by means of bisphenol A and nonylphenol via intracellular estrogen receptors.

References



Nonphyenol and Nnonylphenol Ethoxylates Action Plan. U.S. Enivronmental Protection Agency (EPA). August 2010. Accessed 9/22/2011.


SEPA. Scottish Environment Protection Agency. Accessed 9/22/2011.


WHO. World Health Organization. Integrated Risk Assessmnet: Nonylphenol Case study.


Pesticide Action Network North America. PANNA. Nonylphenol Etoxylates.. Accessed 9/30/2011.

UK Environment Agency


CAS Lab. Columbia Analytical services. Accsessed 9/22/2011.

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