TY - JOUR
T1 - Analysis of chlorpyrifos exposure and human health
T2 - Expert panel report
AU - Albers, James W.
AU - Cole, Philip
AU - Greenberg, Raymond S.
AU - Mandel, Jack S.
AU - Monson, Richard R.
AU - Snodgrass, Wayne R.
AU - Spurgeon, Anne
AU - Gemert, Marcia Van
PY - 1999/1/1
Y1 - 1999/1/1
N2 - Commercial tricresyl phosphate (TCP) is a heterogeneous mixture of isomers and aryl phosphate congeners, known for many years to induce delayed neurotoxicity (OPIDN) in humans and experimental animals. In the past the isomer tri-o-cresyl phosphate (TOCP) was thought to be the component primarily responsible for OPIDN. It is now clear that other constituents, particularly the mono-o-esters, are not only neurotoxic but also may be more potent than pure TOCP. As a generality, the toxicity potential of a particular brand of TCP is related to its content of o-phenolic residues, whereby the maximal potential is reached when o-phenolics are 33% of the mix. Historically, human TCP toxicity has resulted from inadvertent or intentional contamination of foodstuffs or beverages. TCP products with high ortho-residues synthesized by older manufacturing methods were involved in most of these cases, and were likely much more neurotoxic milligram for milligram than TOCP. Because of the great variability of TCP products, there are no conventional workplace exposure standards. Based upon data from the hen and cat, estimated human safe exposure rates for pure TOCP are estimated to be 2.5 mg/kg for a single dose, and 0.13 mg/kg/d for repetitive exposures. These levels may also be applied to TCP when o-methyl-phenyl, o-ethyl-phenyl, and o-xylenyl components are appropriately limited during manufacture such that the TCP product is less neurotoxic than TOCP. There have been relatively few reports of toxicity associated with the manufacture or use of TCP in commerce and industry. Low vapor pressures of the constituents preclude the presence of significant quantities of TCP vapor in the atmosphere. A lubricant or other formulation containing TCP may appear in the air as a mist. By these criteria the U.S Petroleum Oil Mist exposure standard is protective when the formulation contains 4% or less of low ortho-TCP. Exposure calculations indicate that estimated safe levels are not likely to be exceeded in the well-regulated workplace. If it is of short duration, even a heavy fog of oil particulate may not exceed the 8-h-average inhalation exposure standard. Modern manufacturing practices tend to minimize the ortho content and thus the toxicity of TCP. Because individual TCP brands and synthesis methods vary, manufacturers should be consulted concerning the properties of their individual products.
AB - Commercial tricresyl phosphate (TCP) is a heterogeneous mixture of isomers and aryl phosphate congeners, known for many years to induce delayed neurotoxicity (OPIDN) in humans and experimental animals. In the past the isomer tri-o-cresyl phosphate (TOCP) was thought to be the component primarily responsible for OPIDN. It is now clear that other constituents, particularly the mono-o-esters, are not only neurotoxic but also may be more potent than pure TOCP. As a generality, the toxicity potential of a particular brand of TCP is related to its content of o-phenolic residues, whereby the maximal potential is reached when o-phenolics are 33% of the mix. Historically, human TCP toxicity has resulted from inadvertent or intentional contamination of foodstuffs or beverages. TCP products with high ortho-residues synthesized by older manufacturing methods were involved in most of these cases, and were likely much more neurotoxic milligram for milligram than TOCP. Because of the great variability of TCP products, there are no conventional workplace exposure standards. Based upon data from the hen and cat, estimated human safe exposure rates for pure TOCP are estimated to be 2.5 mg/kg for a single dose, and 0.13 mg/kg/d for repetitive exposures. These levels may also be applied to TCP when o-methyl-phenyl, o-ethyl-phenyl, and o-xylenyl components are appropriately limited during manufacture such that the TCP product is less neurotoxic than TOCP. There have been relatively few reports of toxicity associated with the manufacture or use of TCP in commerce and industry. Low vapor pressures of the constituents preclude the presence of significant quantities of TCP vapor in the atmosphere. A lubricant or other formulation containing TCP may appear in the air as a mist. By these criteria the U.S Petroleum Oil Mist exposure standard is protective when the formulation contains 4% or less of low ortho-TCP. Exposure calculations indicate that estimated safe levels are not likely to be exceeded in the well-regulated workplace. If it is of short duration, even a heavy fog of oil particulate may not exceed the 8-h-average inhalation exposure standard. Modern manufacturing practices tend to minimize the ortho content and thus the toxicity of TCP. Because individual TCP brands and synthesis methods vary, manufacturers should be consulted concerning the properties of their individual products.
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U2 - 10.1080/109374099281151
DO - 10.1080/109374099281151
M3 - Article
C2 - 10596300
AN - SCOPUS:0345395458
SN - 1093-7404
VL - 2
SP - 281
EP - 300
JO - Journal of Toxicology and Environmental Health - Part B: Critical Reviews
JF - Journal of Toxicology and Environmental Health - Part B: Critical Reviews
IS - 4
ER -