Limited Sampling Indicates The Reasonable Possibility of Ubiquitous Exposure To The Phthalate DEHP In The U.S. Population
Serendipity has often provided unanticipated insights into chemistry and toxicology, among other fields.
Developing a new defense strategy [FAEDER, BRUYA, & CLARKE, 2011] for a Proposition 65 [OEHHA, 2012A] case in California, the authors undertook a variety of QA/QC procedures to be assured that their test results regarding exposure to DEHP [Toxnet, 2012A] from the consumer product at issue had precision and validity. One such procedure was to ascertain if the test subjects had measurable DEHP on their hands prior to the test in which they handled the product at issue.
The result of that QA/QC assessment presented the unanticipated, but reasonable possibility that the U.S. population is, in general, widely exposed to the phthalate DEHP while engaged in typical day-to-day activities.
I. THE QA/QC ASSESSMENT
One of the QA/QC procedures used to develop expert assessment in the Proposition 65 case in California involved the following assessment to determine if DEHP was present on the hands of test subjects prior to their handling of the product at issue:
- 3 male volunteers were selected.
- On a Friday at close-of-business, each washed their hands with liquid hand soap; thereafter, distilled water was used on the hands as a rinse. [FAEDER, BRUYA, & CLARKE, 2012A] The hands were dried. This distilled water rinse was then followed by a rinsing of the hands with isopropanol to remove any DEHP from the hands of the 3 volunteers.
- Thereafter their hands were sampled by, once again, rinsing with isopropanol in order to ascertain if any DEHP was present after the aforenoted wash and rinse processes.
- The rinsate from the second isopropanol rinse was assessed for the presence of DEHP using EPA Method 8270. No DEHP was detected in the rinsate.
- All subjects were told to engage in their usual activities over the weekend, and to shower Monday morning.
- Upon arrival at the lab Monday morning, the 3 male volunteers were asked to confirm that they had showered before coming to the lab. Thereafter, the hands of the three test subjects were rinsed with isopropanol.
- The isopropanol rinsate was analyzed using EPA Method 8270.
The results of the sampling showed that DEHP was present on the hands of each of the three subjects at amounts between 26 and 33 micrograms.
II. THE DISCUSSION
The Hazardous Substances Data Bank indicates that DEHP is present in a wide variety of consumer products (e.g. imitation leather, rainwear, footwear, upholstery, flooring, wire and cable products, tablecloths, shower curtains, food packaging materials, and children’s toys). [TOXNET, 2012B] Most likely the presence of DEHP in these products arises from the use of polyvinyl chloride resins in the products. The DEHP helps to provide “flexibility” in the product when the product is exposed to shock or torsion. The DEHP, thus, could be seen as helping to maintain the structural integrity of the product.
A general assessment of exposure pathways relevant to the product at issue and many of the products noted above would anticipate that loading occurs principally on the hands. [FAEDER, BRUYA, & CLARKE, 2012B] Using OEHHA’s Proposition 65 Interpretative Guideline No. 2011-001 [OEHHA, 2011A] and OEHHA’s Air Toxics Hot Spots Program Risk Assessment Guidelines (Public Review Draft Nov. 2011) [OEHHA, 2011B], one would expect that no more than half of the DEHP found on the hands would be ingested into the body, and that approximately 9% of the DEHP found on the skin (including the hands) would be absorbed through the skin and thus conveyed into the body.
Although the amounts found on the hands of the test subjects, following a weekend of “normal activities,” were below the Maximum Allowable Dose Level [which under Proposition 65 is 0.001 of the No Observable Effects Level] [FAEADER, BRUYA, & CLARKE, 2012C & 2012D] established by OEHHA pursuant to Proposition 65 for DEHP as a Reproductive Toxicant [OEHHA, 2012B] by Oral Exposure [OEHHA, 2005], an assessment of the synergistic and antagonistic effects of all phthalates and other estrogen mimetic substances within the human body, including exposure to fetuses, is necessary to evaluate the significance of such exposures to the general population.
The authors believe that the funding of such an assessment would provide an appropriate benchmark for determining the public health impact, if any, of such exposures and permit scientifically based regulatory action to be taken, assuming any such action is required. For example, steps could be taken under California’s so-called Green Chemistry Program (see http://www.dtsc.ca.gov/pollutionprevention/greenchemistryinitiative/index.cfm) to reduce or eliminate some or all phthalates and other estrogen mimetic substances from consumer products. Similarly, Federal agencies could address the presence of such substances in packaging, containers, and enteric coatings for over-the-counter and prescription drugs and for food. [FAEDER, BRUYA, & CLARKE, 2012E.]
REFERENCES
FAEDER, BRUYA, & CLARKE. 2011. For a truncated description of the newly developed defense strategy employed by the authors in a Proposition 65 case in California, see http://www.rmkb.com/index.cfm/publications/publication-details/?pkid=873.
FAEDER, BRUYA, & CLARKE, 2012A. As a further QA/QC, the soap and paper towels used were sampled for DEHP using EPA Method 8270D. None was found to be present.
FAEDER, BRUYA, & CLARKE, 2012B. This loading is not meant to be exclusive in light of the wide variety of products in which the resin is used. The authors are aware of allegations in Proposition 65 cases filed in California that DEHP-containing materials are used, for example, in the construction of various footwear. Thus, absorption through the skin of the feet may be, in such situations, another mode of loading.
FAEDER, BRUYA, & CLARKE, 2012C. Exposures in excess of the MADL trigger a warning requirement under Proposition 65. This statement is correct even if one assumes that 100% of the amount on the hands of the volunteer test subjects is conveyed into the body, an assumption unlikely to be reflective of reality.
FAEDER, BRUYA, & CLARKE, 2012D. See Title 27, California Code of Regulations, § 25801.
FAEDER, BRUYA, & CLARKE, 2012E. The authors note, for example, that F.D.A. has rejected a petition to ban Bisphenol A from food packaging based on tests that allegedly showed minimal fetal exposure. The authors note that evaluation of a single substance, when science has in recent years identified many estrogen mimics to which humans may be exposed, fails to account for synergistic and antagonistic effects amongst such substances. From a public policy perspective, it is desirable to understand and appreciate all exposures from estrogen mimics as a group because of these potential interactive effects.
OEHHA, 2005. See, for example, an early decision draft on DEHP that can be found at http://oehha.ca.gov/prop65/law/pdf_zip/DEHPoralMADL062405.pdf. The current MADL standards (the amount which, if exceeded, triggers a warning requirement under Proposition 65) for oral exposure to DEHP can be found at Title 27, California Code of Regulations, §§ 25705 (DEHP as a carcinogen) & 25805 (DEHP as a reproductive toxicant).
OEHHA, 2011A. Guideline for Hand-to-Mouth Transfer of Lead through Exposure to Consumer Products. See http://oehha.ca.gov/prop65/pdf/2011handtomouthPb.pdf.
OEHHA, 2011B. Technical Support Document for Exposure Assessment and Stochastic Analysis. See pp. F-61 through F-65 and Table F.5 on p. F-66. The document can be found at www.oehha.org/air/hot_spots/pdf/110711ExposureTSD.pdf.
OEHHA, 2012A. The Proposition 65 web site of the Office of Health Hazard Assessment (“OEHHA”), the Cal-EPA agency charged with administering the law, can be found at http://www.oehha.ca.gov/prop65.html.
OEHHA, 2012B. A “reproductive toxicant”, as that term in used in Proposition 65, means a substance that causes birth defects or reproductive harm (e.g., interferes with male or female fertility). See Title 27 of the California Code of Regulations, Division 4, Chapter 1, Article 8.
TOXNET, 2012A. By “DEHP” the authors are referring to that substance identified more specifically as CAS 117-81-7. Other terms used for this substance can be found on Toxnet (http://toxnet.nlm.nih.gov/) by selecting and searching the Hazardous Substances Data Bank for CAS 117-81-7, selecting DEHP, and clicking on the Synonyms subsection under Synonyms & Identifiers.
TOXNET, 2012B. The uses of DEHP in various products can be found by logging on to Toxnet (http://toxnet.nlm.nih.gov/) and searching the Hazardous Substances Data Bank for CAS 117-81-7, selecting DEHP, and clicking on the Major Uses subsection under Manufacturing/Use Information.
Author Bios
Edward Faeder, Ph.D., is a toxicologist, specializing in exposure assessment and the chemistry of toxic materials and their effects on people, and is currently the president of SRF Health & Environmental Management Inc. Dr. Faeder has over 23 years of experience with Proposition 65 cases, having been involved with such matters since its passage in 1986.
James Bruya, Ph.D., is president of Friedman & Bruya Inc., an analytical chemical laboratory in Seattle. Dr. Bruya has over 14 years of experience with Proposition 65 cases. Dr. Bruya’s laboratory analyzes samples from around the world for the presence of potentially hazardous chemicals. Their website is www.friedmanandbruya.com/.
Thomas H. Clarke, Jr., J.D., M.S., is a partner in the San Francisco office of Ropers Majeski Kohn & Bentley, and chairman of the firm's Environmental Defense Group. Mr. Clarke has been involved in Proposition 65 litigation for over 15 years and writes the blog, Ear to the Ground, http://eartotheground.typepad.com/. He has frequently lectured and written about Proposition 65, Environmental Law, and the interplay between toxicology & public policy.
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