Concentrations of Selected Elements in Unfinished Wood and Other Natural Materials” March 2015
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CPSC Staff Statement on the Toxicology Excellence for Risk Assessment Report, “Concentrations of Selected Elements in Unfinished Wood and Other Natural Materials” March 2015 The report titled, “Concentrations of Selected Elements in Unfinished Wood and Other Natural Materials,” presents the findings of research conducted by Toxicology Excellence for Risk Assessment (TERA) under a contract with the U.S. Consumer Product Safety Commission (CPSC). TERA performed this research to characterize the concentration of seven named elements1 in unfinished woods, cotton, wool, linen, silk, bamboo, and beeswax. This research was completed in support of CPSC’s work on third party testing burden reduction consistent with assuring compliance. CPSC staff will consider this information in evaluating whether staff could make a recommendation for a Commission determination that some materials do not contain any of the seven elements in concentrations above the solubility limits listed in Table 1 of ASTM F963-11, Standard Consumer Safety Specification for Toy Safety, (the Toy Standard), and thus, may not require third party testing to assure compliance with that portion of the standard. This report will be posted on CPSC’s website to keep stakeholders informed of the progress of technical research related to the agency’s regulatory activities 1 The elements researched are antimony, arsenic, barium, cadmium, chromium, mercury, and selenium. The Commission previously determined that lead was not present in the materials specified. Concentrations of Selected Elements in Unfinished Wood and Other Natural Materials Task Order 9 Contract Number CPSC-D-12-0001 March 2, 2015 Final Report Prepared by: Toxicology Excellence for Risk Assessment (TERA) Contact: Jacqueline Patterson [email protected] Alison Willis [email protected] Contents List of Figures ................................................................................................................................................................ 4 List of Tables ................................................................................................................................................................. 4 Abbreviations ................................................................................................................................................................ 5 1. Introduction ........................................................................................................................................................... 7 2. Approach and Methods .......................................................................................................................................... 8 2.1 Literature Review Strategy......................................................................................................................... 11 2.1.1 Group 1 .................................................................................................................................................. 11 2.1.2 Group 2 .................................................................................................................................................. 14 2.1.3 Group 3 .................................................................................................................................................. 15 3. Transfer of Elements to the Natural Materials ..................................................................................................... 16 3.1 Plant uptake of elements ............................................................................................................................ 17 3.2 Environmental Concentrations and Bioavailability (Factors 2 and 3) ........................................................ 20 3.2.1 Antimony ............................................................................................................................................... 20 3.2.2 Arsenic ................................................................................................................................................... 22 3.2.3 Barium ................................................................................................................................................... 24 3.2.4 Cadmium ............................................................................................................................................... 25 3.2.5 Chromium .............................................................................................................................................. 26 3.2.6 Mercury ................................................................................................................................................. 28 3.2.7 Selenium ................................................................................................................................................ 29 4. Group 1 Results: Unfinished Wood, Bamboo, Beeswax ..................................................................................... 31 4.1 Unfinished Wood ....................................................................................................................................... 31 4.1.1 Antimony ............................................................................................................................................... 31 4.1.2 Arsenic ................................................................................................................................................... 33 4.1.3 Barium ................................................................................................................................................... 37 4.1.4 Cadmium ............................................................................................................................................... 37 4.1.5 Chromium .............................................................................................................................................. 40 2 4.1.6 Mercury ................................................................................................................................................. 44 4.1.7 Selenium ................................................................................................................................................ 46 4.2 Group 1 Results: Bamboo .......................................................................................................................... 47 4.3 Group 1 Results: Beeswax ......................................................................................................................... 48 4.4 Group 2 Results: Silk ................................................................................................................................. 50 4.5 Group 2 Results: Linen .............................................................................................................................. 52 4.6 Group 2 Results: Cotton ............................................................................................................................. 54 4.7 Group 2 Results: Wool ............................................................................................................................... 56 5. Discussion ............................................................................................................................................................ 58 5.1 Concentrations of ASTM Elements in Group 1 and 2 Materials ............................................................... 60 5.2 Concentrations in Trees, Bamboo Plants, Silkworms, Flax Plants, and Cotton Plants .............................. 61 5.3 Potential for Accumulation from the Environment or Agriculture ............................................................ 62 5.4 Introduction of Elements through Processing or Packaging ...................................................................... 64 6. References ........................................................................................................................................................... 66 Appendix I - Data Tables for Concentrations Below Solubility Limits Appendix II - Literature Search Strategy 3 List of Figures Figure 1. Hierarchy for data investigation ................................................................................................................... 10 Figure 2. A conceptual model for mechanisms of element exposure and potential uptake. Taken from EPA, 2003 ..................................................................................................................................................................................... 17 List of Tables Table 1. Material Groups, Solubility Limits, and Material Types for Selected Elements ............................................. 7 Table 2. Studies reviewed that measured antimony concentrations in trees above the solubility limit (SL) of 60 mg/kg (ppm). ............................................................................................................................................................... 32 Table 3. Studies measuring arsenic concentrations in trees above the solubility limit (SL) of 25 mg/kg (25 ppm) ..................................................................................................................................................................................... 34 Table 4. Studies measuring cadmium concentrations in trees above the solubility limit (SL) of 75 mg/kg