Telomere length: A possible link between phthalate exposure and cancer development?

Phthalates or phthalic acid esters are a class of synthetic chemicals used as plasticizers to soften polyvinyl chloride (PVC) in a wide range of consumer and personal care products. Phthalates are released into the environment and taken up by the general population mainly through ingestion, inhalation, and dermal contact. Phthalates are lipid soluble, have relatively short (less than 24 h) biological half-lives, and are quickly excreted in urine and feces. The measurement of phthalate metabolites in urine is currently themost accepted method in epidemiology studies for assessing phthalate exposure (Johns et al., 2015). Phthalates have been classified as endocrine disrupting chemicals and linked to adverse health effects (Singh and Li, 2012; Roy et al., 2015; Caldwell, 2012). The International Agency for Research on Cancer classified di-2-ethylhexyl phthalate (DEHP) as “possibly carcinogenic to humans” (Group 2B). Cumulative evidence from in vitro, animal, and epidemiology studies indicate that phthalates cause DNA damage (Caldwell, 2012), affect DNA methylation (Singh and Li, 2012), alter expression of certain genes (Roy et al., 2015; Caldwell, 2012), and increase cell proliferation (Caldwell, 2012). In this issue of EBioMedicine, Scinicariello et al. (2016) evaluated the association of phthalate exposure with blood leukocyte telomere length (LTL). Telomeres, tandem hexametric nucleotide repeats (TTAGGG)n located at the end of chromosomes, are specialized chromatin structures essential for the maintenance of chromosomal integrity and stability. Telomeres are essential for the complete replication of DNA, and for protecting chromosomes from nuclease degradation, end-to-end fusion, and cellular senescence, thus playing a key role in promoting chromosome integrity and stability. Retrospective case–control studies have shown that shorter LTL is associated with increased cancer risk, while studies from prospective studies have found that both shorter and LTL are