Humans are exposed to phthalates through ingestion, inhalation, and dermal exposure during their whole lifetime. Preventive limit values, such as reference dose (RfD) of the US Environmental Protection Agency (US EPA) and tolerable daily intake (TDI) of the European Union, are 20 mgperkg of body weight per day and 37 mgperkg of body weight per day, respectively. It has been shown that the general population can be exposed to DEHP to a much higher extent than previously believed, and exposure of children at levels twice as high as the exposure of adults with respect to their body weight has been observed.
Phthalates are rapidly metabolized in humans to their respective monoesters, which, depending on the phthalate, can be further metabolized to oxidative products of their lipophilic aliphatic side chain. Monoesters and the oxidative metabolites of phthalates may be conjugated as the glucuronide (phase II biotransformation), and both free and conjugated metabolites can be excreted in urine and feces.
In animal studies, a wide variety of adverse effects were linked to phthalate exposure; the level of exposure in these experiments was, however, several times higher as in actual day-to-day exposures.
Phthalates are carcinogenic to animal and can cause fetal death, malformations, testicular injury, liver injury, anti-androgenic activity, teratogenicity, peroxisome proliferation, and especially reproductive toxicity in laboratory animals. Toxicity profiles and potency vary by specific phthalate. The extent of these toxicities and their applicability to humans remains incompletely characterized and controversial.
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