Health effects of di-n-octylphthalate (DNOP)
Di-n-octylphthalate, also known as dioctyl phthalate, is a colorless, odorless, oily liquid. It does not evaporate easily. There is no evidence that di-n-octylphthalate occurs naturally in the environment. Di-n-octylphthalate is manufactured for many uses. It is commonly used as a plasticizer (a substance added to plastics to keep them soft or more flexible). These plastics are found in products such as carpetback coating, packaging films, medical tubing and blood storage bags, floor tile, wire, cables, and adhesives. Di-n-octylphthalate is also used in cosmetics and pesticides.
Pathways for di-n-octylphthalate in the environment
Di-n-octylphthalate may enter the environment in industrial waste waters, air emissions, and solid wastes from manufacturing and processing operations, from evaporation of the compound from plastics, from the burning of plastic products, and by leaking from plastics in landfills into soil or water, including groundwater. Di-n-octylphthalate is expected to stick tightly to soil, sediment, and dust particles once it is released to the environment. If released to the atmosphere, the compound may be deposited on the ground or to surface water in rain or dust particles. Small amounts of the compound can build up in animals that live in water, such as fish and oysters. The compound breaks down into other products mainly by the action of microorganisms. Additional ways di-n-octylphthalate is transformed into other substances include reaction with sunlight and other chemicals present in the atmosphere, reaction with water, and breakdown of the compound in surface waters by sunlight.
Exposure to di-n-octylphthalate
You may be exposed to di-n-octylphthalate by eating foods contaminated with any of the compound that has leaked from plastic containers, by eating certain foods, such as fish, that have built up high levels of the compound, and by drinking contaminated water. You may also be exposed to di-n-octylphthalate during medical treatments such as blood transfusions and dialysis that use equipment made of plastics containing di-n-octylphthalate. In addition, if you live near a hazardous waste site or an industrial manufacturing or processing facility, you may be exposed through contact with air, water, or soil that may have been contaminated around these sites. Little information is available about the concentrations of di-n-octylphthalate in air, water, or soil. The compound has been measured at 0.06 0.94 parts di-n-octylphthalate per trillion parts of air (ppt), in rain at 2.6 20 ppt, in river water at 1 310 ppt, and in sediment at less than 5 25,000 ppt.
Workers in the chemicals and plastics industries may also be exposed to di-n-octylphthalate. The National Occupational Exposure Survey estimated that 10,393 individuals were exposed to the compound in the workplace in 1980.
Pathways for di-n-octylphthalate in the body
Di-n-octylphthalate can enter your body when you drink water or eat food containing it. We do not know if di-n-octylphthalate enters your body when you breathe air containing it or when it comes in contact with your skin. It is possible that exposure could occur near hazardous waste sites, at manufacturing facilities, or through the use of consumer products containing the substance. We do not know how much you will absorb if you eat or drink it.
Di-n-octylphthalate can also enter your body during medical treatment through the use of plastic tubing or storage bags contaminated with di-n-octylphthalate. Once it enters your body, it breaks down into other chemicals and the health effects of some of these chemicals are not well understood. Di-n-octylphthalate and its breakdown products will leave your body mostly in your urine, but we do not know how quickly that happens. We do not know if the compound or its breakdown products will remain in the tissues.
Health effects of di-n-octylphthalate
No information is available regarding the possible effects caused by di-n-octylphthalate if you breathe, eat, drink, or have skin contact with it. Furthermore, there is no information on the effects of breathing di-n-octylphthalate in laboratory animals. Di-n-octylphthalate has caused death in some rats and mice given very high doses by mouth. Mildly harmful effects have been seen in the livers of some rats and mice given very high doses of di-n-octylphthalate by mouth for short or intermediate durations of time. Brief oral exposures to lower doses of di-n-octylphthalate generally caused no harmful effects.
You should know that one way to learn whether a chemical will harm people is to determine how the body absorbs, uses, and releases the chemical. For some chemicals, animal testing may be necessary. Animal testing may also help identify such health effects as cancer or birth defects. Without laboratory animals, scientists would lose a basic method for getting information needed to make wise decisions that protect public health. Scientists have the responsibility to treat research animals with care and compassion. Scientists must comply with strict animal care guidelines because laws today protect the welfare of research animals.
Additionally, there are vigorous national and international efforts to develop alternatives to animal testing. The efforts focus on both in vitro and in silico approaches and methods. For example, the National Toxicology Program (NTP) at the National Institute of Environmental Health Sciences (NIEHS) created the NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM) in 1998. The role of NICEATM is to serve the needs of high quality, credible science by facilitating development and validation—and regulatory and public acceptance—of innovative, revised test methods that reduce, refine, and replace the use of animals in testing while strengthening protection of human health, animal health and welfare, and the environment. In Europe, similar efforts at developing alternatives to animal based testing are taking place under the aegis of the European Centre for the Validation of Alternative Methods (ECVAM).
We have no information on the health effects of di-n-octylphthalate when applied to the skin of humans for long periods of time. Di-n-octylphthalate can be mildly irritating when applied to the skin of animals. It can also be slightly irritating when put directly into the eyes of animals.
We do not know if di-n-octylphthalate causes cancer in humans or animals. Unlike other phthalates such as di(2-ethylhexyl)phthalate, di-n-octylphthalate does not appear to affect the ability of male animals to father offspring. Some birth defects occurred in newborn rats whose mothers received high doses (approximately 5 grams per kilogram of body weight [5 g/kg]) of di-n-octylphthalate by injection during pregnancy. However, humans are not exposed to di-n-octylphthalate this way, and no harmful effects on developing fetuses were seen when mice were given this chemical by mouth.
Di-n-octylphthalate has not been classified for carcinogenic effects by the Department of Health and Human Services, the International Agency for Research on Cancer, or the EPA.
Medical tests for exposure to di-n-octylphthalate
Di-n-octylphthalate and its principal breakdown products can be measured in urine, blood, and tissues. However, the information available on these tests is so limited that it is not possible to know if they are specific for di-n-octylphthalate, if they can be used to determine how much you were exposed to, if they can predict whether harmful health effects will occur, or how long the test is useful after exposure occurs. These tests are not available in doctors' offices.
Disclaimer: This article is taken wholly from, or contains information that was originally published by, the Agency for Toxic Substances and Disease Registry. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the Agency for Toxic Substances and Disease Registry should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.