Mono Phthalate Esters and Metabolites
With studies demonstrating toxicity in animals and the high potential for human exposure from consumer products, mono phthalate esters are receiving increasing scrutiny from the scientific community and regulators as a possible public health issue. With recent studies revealing that most of the US general population have very low levels phthalate esters, phthalate ester metabolites have securely placed themselves as an emerging contaminant of concern. A clearer understanding of possible human effects is necessary. AXYS provides low level measurement of monophthalate esters and their conjugates by LC/MS/MS instrumentation for use in Body Burden studies.
Used for over 50 years, phthalates are a family of compounds with a diester structure consisting of a 1,2-benzenedicarboxylilc acid head group linked to two ester side chains. Phthalate esters generally refer to compounds where the carboxylic acid functional group and ester side chain arise from adjacent carbon atoms of the benzene ring. Ester side chains, commonly ranging from C1 to C13, may be linear, branched or a combination of linear, branched, and ringed. Generally both side chains are structurally identical. All of these characteristics affect the physicochemical and toxicological properties of the phthalate.
Phthalate esters are rapidly metabolized by the body and excreted in urine and feces. Primary metabolism by hydrolysis of one of the ester bonds results in monoesters. Further oxidation may also occur resulting in oxidative metabolites. Monoesters and oxidative metabolites may undergo phase II biotransformation to produce glucuronide conjugates which increases their water solubility and therefore ability to be excreted. It is the Monoesters that are thought to be toxic agents.
Phthalate ester measurement at the levels of concern has been difficult as most laboratories have significant blank or background levels of these compounds. Measurement of phthalate ester metabolites and their conjugates greatly reduces this effect. AXYS has analyzed mono phthalate esters and metabolites by LC / MS/MS instrumentation in urine since 2006. Typical report limits are in ng/mL range.
Used in a wide variety of applications, phthalates are most commonly used as plasticizers in polyvinyl chloride to make vinyl soft and flexible and, to a much lesser extent, as additives in lubricant, paints, pesticides, and Personal Care Products (PCP) such as nail polish and fragrances. It is estimated that more than four million tons of phthalates are consumed globally per year. Di-(2-ethylhexyl) phthalate (DEHP) is one of the most commonly used phthalates, particularly in PCPs.
Since phthalate esters break down quickly and undergo rapid metabolism, mono phthalate esters are not thought to pose an immediate environmental concern. However, the concern regarding these emerging compounds lies with widespread human exposure. During a 1999-2000 National Health and Nutrition Examination Survey, MEHP was found in 78% of the US population. Phthalates are not chemically bound in plastics, thus exposure is thought to be through consumption of food and water products packaged in plastic, inhalation, and dermal exposure from the application of products containing phthalates. Once absorbed in the body they are readily metabolized to monoesters, oxidative metabolites, and glucuronide conjugates which may be excreted in urine or feces. Monoesters of phthalates are thought to display the most toxicity. Estrogenic effects on humans are the prime concern, although monophthalate esters are also thought to be carcinogenic. Very limited studies have been conducted with humans, however some negative effects have been noted. Some phthalate esters are being considered for regulation by Environment Canada and the US EPA as it is thought that previous levels used in toxicology and risk assessment for environmental levels may have been high enough to disrupt estrogenic endpoints of concern. It is certain that more studies need to be conducted to determine the full extent of exposure and environmental effects.
AXYS specializes in measurement of monophthalate esters to nanogram or lower concentrations from standard sample sizes. Our specialized sampling and analytical procedures may allow for much lower detection limits and reduced sample sizes in human and sediment matrices. We deliver legally defensible data under ISO 17025 certified systems applying methods accredited by NELAP and CAEAL. Electronic Data Deliverables (EDD), customized for download to our clients’ relational databases, are available in addition to standard format report and full data packages.
Please contact one of our Project Managers at 1 888 373 0881 or +1 (250) 655-5800 to discuss how AXYS can support your analytical advantage.
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