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Humans are potentially exposed to phthalate esters (PEs) through ingestion, inhalation, and dermal contact. Studies quantifying exposure to PEs include “biomarker studies” and “indirect studies.” Biomarker studies use measurements of PE metabolites in urine to back-calculate exposure to the parent diester, while indirect studies use the concentration of the PE in each medium of exposure and the rate of intake of that medium to quantify intake of the PE. In this review, exposure estimates from biomarker and indirect studies are compiled and compared for seven PEs to determine if there are regional differences and if there is a preferred approach. The indirect and biomarker methods generally agree with each other within an order of magnitude and discrepancies are explained by difficulties in accounting for use of consumer products, uncertainty concerning absorption, regional differences, and temporal changes. No single method is preferred for estimating intake of all PEs; it is suggested that biomarker estimates be used for low molecular weight PEs for which it is difficult to quantify all sources of exposure and either indirect or biomarker methods be used for higher molecular weight PEs. The indirect methods are useful in identifying sources of exposure while the biomarker methods quantify exposure.

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Thermodynamic parameters relevant to the phosphine-modified cobalt hydroformylation reaction are reported. Equilibrium constants for the hydrogenation of Co 2 (CO) 6 L 2 to yield HCo(CO) 3 L were determined using in situ 1 H and 31 P NMR spectroscopy between 75 and 175 °C for various solvents and phosphine ligands. Special emphasis was placed on n-Bu 3 P, as this ligand is prototypical of the Shell hydroformylation process. The resultant van't Hoff plots yield the enthalpy and entropy change (∆H ) 7.0 ( 0.4 kcal/mol and ∆S ) 2 ( 1 cal/mol•K) for the case of L ) n-Bu 3 P in benzene solvent. These parameters were found to be relatively insensitive to changes in the solvent, suggesting that the hydride product is not very polar. Even for isobutyl alcohol solvent, the resultant enthalpy and entropy changes (∆H ) 5.8 ( 0.4 kcal/mol and ∆S ) -2 ( 1 cal/mol•K) were found to be similar to those obtained in benzene and dioxane. Analysis of the 31 P NMR line widths allows rigorous lower limits to be established for the catalytically relevant Co-Co and Co-H bond energies in the case of L ) n-Bu 3 P (Co-Co g 23 kcal/mol and Co-H g 60 kcal/mol) relative to the previously reported values for the case of L ) CO (Co-Co ) 19 ( 2 kcal/mol and Co-H ) 59 ( 1 kcal/mol).