Our Stolen Futurea book by Theo Colborn, Dianne Dumanoski, and John Peterson Myers
 
 

 

 

background on phthalates

Brock, JW, SP Caudill, MJ Silva, LL Needham, and ED Hilborn. 2002. Phthalate Monoester Levels in the Urine of Young Children. Bulletin of Environmental Contamination and Toxicology 68:309–314.


 
 

Brock et al. measured the level of several phthalate metabolites in the urine of 19 children living in the Imperial Valley, California. They found phthalates in all children examined, with levels higher on average than had been reported by Blount et al. (2000) using the same analytical tools to measure phthalate metabolites in a larger sample of American adults.

What did they do? Brock et al. recruited 20 children (ages 12-18 months) for participation in this survey by approaching the parents as the children were brought to a clinic for their measles-mumps-rubella vaccine. Nothing was assumed or known about their potential exposure to phthalates upon recruitment. 18 of the 20 subjects were Latino; 2 were Caucasian. Urine was collected during this clinic visit and a second time during a home visit, about 4 weeks later. The primary caregiver was interviewed using a questionnaire to assess home pesticide use, occupational exposure and proximity to agricultural pesticide use. A second interview was conducted during the home visit, updating the pesticide information and also asking about the use of perfumes, cosmetics and soft plastic toys.

The phthalate measurements were conducted using procedures developed for Blount et al. (2000). Because phthalate exposure is so widespread that laboratory contamination is unavoidable, Brock's lab at the CDC has pioneered a technique that measures the breakdown products of different phthalates in urine, their metabolites, instead of the original (parent) phthalates themselves. According to Blount et al: "This analytical approach allows us to directly measure the individual phthalate metabolites responsible for the reproductive and developmental toxicity of phthalates in animals while avoiding contamination from the ubiquitous parent compound." This approach thus allows Brock's team to confirm that the exposures were real and not due to laboratory contamination, as the laboratory contamination is by the phthalates, not by their metabolites.

They report on the concentrations of the following metabolites:

Parent phthalate
Metabolite
DEP
diethyl phthalate
MEP
monoethyl phthalate
DBP
dibutyl phthalate
MBP
monobutyl phthalate
BzBP
benzyl butyl phthalate
MBzP
monobenzyl phthalate
DEHP
di-(2-ethylhexyl) phthalate

MEHP
mono-(2-ethylhexyl) phthalate

Several other metabolites were measured but were not detected.

What did they find? All children had phthalate metabolites in their urine, indicating exposure to the parent phthalates. For three of the four metabolites, concentrations averaged higher in children than those measured by Blount et al. in adults:

Metabolite
Average in children ng/ml
Percentile in Blount et al.
MEP
246.9
25th-50th
MBP
287.6
75th-100th
MBzP
44.8
50th-75th
MEHP

6.4

50th-75th

None of the measurements of phthalate metabolites showed any correlation with responses to the questionnaires.

What does it mean?

According to Brock et al.:

  "The mean urinary MBP, MBzP and MEHP levels for the children in this study were above the 50th percentile of the previously reported adult levels. This crude comparison neglects to consider that infants produce about one third of the urine volume of adults with about one seventh the body weight. Combining this information suggests that DBP, BzBP and DEHP exposure on a body weight basis may be at least twice as high for these children compared to the adults in NHANES III" [Blount et al.'s sample].  

The types of phthalates detected suggest that exposure is via consumer products such as fragrance-containing soaps, shampoos and perfumes, as well as nail polish and beauty products. The presence of MEHP indicates that another route of exposure was via DEHP-containing toys.

Whether these levels create health risks remains to be established. The higher levels indicate exposures within the range at which effects begin to appear in laboratory experiments with animals. The concluding comments from Blount et al. (2000) are equally germane to these new data:

  From a public health perspective, these data provide evidence that phthalate exposure is both higher and more common than previously suspected. Exposure data for phthalates is critically important for human risk assessment, especially among potentially susceptible populations. Although DEHP and DINP are produced in the largest quantities, these reference range data indicate a substantial internal human dose of DBP, DEP, and BzBP. MBP and MBzP are of particular concern because of their developmental and reproductive toxicity in animals. Therefore, assessments of health risk from exposures to phthalates should include exposures to DBP, DEP, and BzBP.  

 

 

 
     

 

 

 

OSF Home
 About this website
Newest
Book Basics
  Synopsis & excerpts
  The bottom line
  Key points
  The big challenge
  Chemicals implicated
  The controversy
  Recommendations
New Science
  Broad trends
  Basic mechanisms
  Brain & behavior
  Disease resistance
  Human impacts
  Low dose effects
  Mixtures and synergy
  Ubiquity of exposure
  Natural vs. synthetic
  New exposures
  Reproduction
  Wildlife impacts
Recent Important    Results
Consensus
News/Opinion
Myths vs. Reality
Useful Links
Important Events
Important Books
Other Sources
Other Languages
About the Authors
 
Talk to us: email