Phthalates

The National Environmental Protection Measures (NEPMs) are guidelines used to determine the human and ecological risks associated with site contamination within Australia. They list chemicals which potentially contaminate sites, and the concentrations above which a chemical becomes a potentially concern. The NEPMs were updated in mid-2013 and now outline a number of chemicals not previously listed as potential contaminants.


One group of chemicals now outlined in the NEPMs are the wonderfully named phthalates (pronounced THAL-ATES). The NEPMs provide guidelines for four of them and only for concentrations in groundwater. These are di-methyl phthalate (DMP), di-ethyl phthalate (DEP), di-butyl phthalate (DBP), and di-2-ethylhexyl phthalate (DEHP).


The general chemical structure of phthalates

Phthalates have an interesting background. The word “phthalate”, for example, is derived from the word naphthalene. This was in turn derived from either the Greek word for bitumen or Persian word for pitch. 


Phthalates have been in use since the 1940s. They are now used in a great variety of substances including vinyl flooring, shower curtains, deodorants, hair spray, food containers, catheters, tubes, and insect repellents. Their most common utilised as plasticisers in poly-vinyl chloride (PVC), which can containup to 40% of DEHP.

Because phthalates are not chemically bound to plastics but merely dissolved in them, they are easily leachable. Human exposure to phthalates is mostly as a result of this leaching, whereby phthalates leach from plastics and into foods. Some exposure does originate through skin absorption and inhalation.


Investigations into the possible toxicity of phthalates intensified in the 1990s, with experts working to assess the health risks presented by these chemicals. Research found that phthalates are endocrine disrupting chemicals – that is they disturb the normal balance of hormones in animals. Similar to other chemicals based on phenolic rings, phthalates are xenoestrogens, acting as oestrogens within animals’ bodies. Some phthalates, namely DEHP and DBP, have also been found to act as anti-androgens, whereby they disturb the normal production of male hormones.


While these research results mean phthalates have the potential to impact on human reproductive health, the same reproductive hormones in humans – testosterone, oestrogen and many more – occur throughout the animal kingdom. Recent research on laboratory rats, for example, showed that in some cases phthalate exposure led to Androgen Insufficiency Syndrome with symptoms including insufficient production of male hormones.


In more extreme cases phthalate exposure led to Phthalate Syndrome, where infertility, decreased sperm count, undescended testes, malformation of the penis in which the urethra does not end at the end of the penis, and other reproductive tract malformations occur. Di-butyl phthalate was also found to cause severe reproductive impacts on aquatic animals.


Phthalates are released to the environment from a variety of sources, including including industrial releases, manufacturing, processing and industrial wastes, municipal solid waste, land application of sewage sludge, and from products containing phthalates, including the plastic bottles used for water and soft drinks. Indeed, the pervasive and global use of plastics has ledto phthalates in a wide variety of environments across the world.


A study of groundwater collected from a residential area, a light-industrial area, and from beside a major arterial road in Western Australia, found phthalates in 11 of 12 samples collected. Di-2-ethylhexyl phthalate was detected in every water sample collected from a number of rivers, lakes, and sewage treatment plants in a German study. Japanese rainwater, drinking water in the USA, and groundwater in the Netherlands, were also found to contain phthalates.


Although phthalates are ubiquitous in the aquatic environment they have negligible to low water solubility. Di-2-ethylhexyl phthalate, for example, will neither leach from soils nor evaporate, and biodegrades in two to three weeks if washed into water. Di-butyl phthalate instead breaks down in one and a half days in an aquatic environment. Di-ethyl phthalate has many sources and is found pretty much everywhere, from river water, to groundwater, where it partitions to sediments and soils and undergoes biodegradation. The fact that phthalates are found in such a range of water environments, despite their low solubility and propensity for water transport, is evidence of their ubiquitous use and global occurrence of plastics.


The assessment of phthalate contamination in groundwater is difficult because of their ubiquitous occurrence, with many opportunities for water samples to be contaminated in the sampling process. As environmental scientists we use and expose water to any number of plastic and or potentially phthalate containing equipment and instruments – bailers, pumps, filters, the plastic lids on the bottles, gloves, the boxes to store the bottles, the plastic interiors of our cars, and the vessels in which milli-q water is stored to name just a few.


Laboratories also have the potential to introduce phthalates into water samples received, as phthalates occur in a wide range of laboratory equipment and even in the dust within buildings.


These potential sources of sample contamination do not necessarily affect the comparison of groundwater samples to the NEPMs, as it is not the detection of phthalates but the concentration at which they occur which is used to evaluate risk within these guidelines. The ubiquitous nature of phthalates does highlight the need for the appropriate collection of laboratory, trip, rinsate, and field blanks, however, so the amount of phthalate introduced to a sample at different stages of collection and analysis can at least be measured, if not eliminated completely.


Below is a summary of information pertaining to the four phthalates outlined in the NEPMs.


DBP

DMP

DEP

DEHP

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Murrang Earth Sciences Pty Ltd
Canberra, Australia

ABN: 96 162 928 958

Page last updated 1 April 2020

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