Selecting adequate exposure biomarkers of diisononyl and diisodecyl phthalates: data from the 2005-2006 National Health and Nutrition Examination Survey.
BACKGROUND
High-molecular-weight phthalates, such as diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP), are used primarily as polyvinyl chloride plasticizers.


OBJECTIVE
We assessed exposure to DINP and DIDP in a representative sample of persons ≥ 6 years of age in the U.S. general population from the 2005-2006 National Health and Nutrition Examination Survey (NHANES).


METHODS
We analyzed 2,548 urine samples by using online solid-phase extraction coupled to isotope dilution high-performance liquid chromatography-tandem mass spectrometry.


RESULTS
We detected monocarboxyisooctyl phthalate (MCOP), a metabolite of DINP, and monocarboxyisononyl phthalate (MCNP), a metabolite of DIDP, in 95.2% and 89.9% of the samples, respectively. We detected monoisononyl phthalate (MNP), a minor metabolite of DINP, much less frequently (12.9%) and at concentration ranges (> 0.8 µg/L-148.1 µg/L) much lower than MCOP (> 0.7 µg/L- 4,961 µg/L). Adjusted geometric mean concentrations of MCOP and MCNP were significantly higher (p < 0.01) among children than among adolescents and adults.


CONCLUSIONS
The general U.S. population, including children, was exposed to DINP and DIDP. In previous NHANES cycles, the occurrence of human exposure to DINP by using MNP as the sole urinary biomarker has been underestimated, thus illustrating the importance of selecting the most adequate biomarkers for exposure assessment.
Calafat
Antonia M
AM
Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia 30341, USA. Acalafat@cdc.gov
Wong
Lee-Yang
LY
Silva
Manori J
MJ
Samandar
Ella
E
Preau
James L
JL
Jia
Lily T
LT
Needham
Larry L
LL
D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000652:urine; D002648:Child; D004781:Environmental Exposure / Q000032:analysis* / Q000592:standards; D004784:Environmental Monitoring / Q000379:methods / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D010795:Phthalic Acids / Q000592:standards / Q000652:urine*; D055815:Young Adult
D015415:Biomarkers; D010795:Phthalic Acids; C012125:diisononyl phthalate; C042080:diisodecyl phthalate