143. Phosphate triesters with flame retardant properties

Abstract

Summary Sjögren B, Iregren A, Järnberg J. The Nordic Expert Group for Criteria Documentation of Health Risks from Chemicals. 143. Phosphate triesters with flame retardant properties. Arbete och Hälsa 2010;44(6):1-220. This document comprises the following phosphate triesters: Tricresyl phosphate TCP Triethyl phosphate TEP Tris(2-butoxyethyl) phosphate TBEP TIPP Tri-n-butyl phosphate TBP Triisopropylated phenyl phosphate/ isopropylated triphenyl phosphate Tris(2-chloroethyl) phosphate TCEP Tris(monochloropropyl) phosphate TMCPP Tris(1,3-dichloro-2-propyl) phosphate TDCPP Triphenyl phosphate TPP Tris(2-ethylhexyl) phosphate TEHP The phosphate triesters are mainly used as flame retardants and plasticisers. They differ widely in physical properties as well as toxicological profiles and toxic potency. Most of these esters have low vapour pressures and are presumably absorbed to a substantial degree by the skin. The dermal exposure route may therefore be more important than inhalation. Human toxicological data on the phosphate triesters are scarce, particularly regarding occupational inhalation exposure. Based on animal data, the critical effects vary depending on substance and include cholinesterase inhibition, neurotoxicity, cancer, reproductive toxicity, and liver and kidney toxicity. Organophosphorus-induced delayed neuropathy (OPIDN) has been associated with exposure to some triaryl phosphates. The most well-known example is the TCP isomer tri-ortho-cresyl phosphate (TOCP), which has been associated with numerous cases of poisoning worldwide. The TOCP content is therefore kept at a very low level in commercial phosphate ester products of today. Commercial products of TCP, TIPP and TPP may, however, contain other triaryl phosphates associated with OPIDN. Several other phosphate triesters have shown other (non- OPIDN) neurotoxic effects in animals. Some of the esters covered in this document exhibit carcinogenic effects in animals (TBP, TCEP, TDCPP and TEHP), whereas TCP shows no such potential. The other esters have not been properly tested. The lowest observed adverse effect levels (LOAELs) of the phosphate triesters range from 5 to 600 mg/kg bw/day. The no observed adverse effect levels (NOAELs), only identified for TBEP, TBP and one commercial product of TIPP, are in the range 9-20 mg/kg bw/day.