Estimating pesticide dose from urinary pesticide concentration data by creatinine correction in the Third National Health and Nutrition Examination Survey (NHANES-III)

Abstract

The Third National Health and Nutrition Examination Survey (NHANES-III) of the Centers for Disease Control and Prevention (CDC) recorded data on the urinary concentrations of 12 chemicals (analytes), which were either pesticides or their metabolites, that represent exposure to certain pesticides, in urine samples collected from 1988 to 1994 from a cohort of 978 volunteer subjects, aged 20-59 years. We have used each subject's urinary creatinine concentration and their individual daily creatinine excretion rate (g/day) computed from their age, gender, height and weight, to estimate their daily excretion rate in mg analyte/kg/day. We discuss the mechanisms of excretion of the analytes and certain assumptions needed to compute the equivalent daily dietary intake (mg/kg/day) of the most likely parent pesticide compounds for each excreted analyte. We used literature data on the average amount of parent compound ingested per unit amount of the analyte excreted in the urine, and compared these estimated daily intakes to the US EPA's reference dose (RfD) values for each of those parent pesticides. A Johnson S B distribution (four-parameter lognormal) was fit to these data to estimate the national distribution of exclusive exposures to these 12 parent compounds. Only three such pesticides had a few predicted values above their RfD (lindane 1.6%; 2,4-dichlorophenol 1.3%; chlorpyrifos 0.02%). Given the possibility of a subject's dietary intake of a pesticide's metabolites incorporated into treated food, our results show that few, if any, individuals in the general US population aged 20-59 years and not employed in pesticide application were likely to have exceeded the USEPA RfD for these parent compounds during the years studied.

Creatinine corrections for estimating children's and adult's pesticide intake doses in equilibrium with urinary pesticide and creatinine concentrations

“…The estimated CE rate from 18 years through adulthood has been reported (Mage et al 2004). They used a derivation based on the creatinine clearance equations of Cockcroft and Gault (1976), who measured 24-h urine collections for 249 male and 18 female adults in the age range from 18 to 92 years.…”

“…In addition, we compare the race-corrected adult results to the urinary perchlorate data, analyzed by Blount et al (2007) for adults 20 years and older using the equations (Mage et al, 2004) without the corrections for Black race.…”

“…Thus, there is interest in relating urine or blood concentrations of pesticides in the population to exposures of pesticide residues and to how these exposures relate to the RfD. Replicable children's creatinine correction methods extend the work previously completed for adults (Mage et al, 2004) and the usefulness of NHANES human biomonitoring data on pesticides for regulatory risk analyses and indicator development, by reduction of uncertainty in single spot urine sampling reported as concentration alone.…”

“…By creatinine correction. One can convert the urinary analyte per mg of creatinine into an equilibrium daily excretion of the pesticide analyte that corresponds to a daily intake (mg/kg/day) for comparison with the RfD level of the parent pesticide (Boeniger et al, 1993;Mage et al, 2004). Creatinine is a natural metabolic product of creatine that occurs in muscle tissue and an approximately constant amount of creatinine is produced daily with additional excretion of dietary creatinine and metabolized dietary creatine.…”

“…The latter creatinine approach is simpler than the PBPK approach, and it has been utilized by Mage et al (2004) for male and female adults (18oageo92 years) with the daily adult CE relationships of Cockcroft and Gault (1976). They compared the urinary pesticide analyte concentrations in NHANES III to RfD for the appropriate parent pesticide.…”