Dermal absorption exposure of lead from guitar strings . .... The nickel-plated
steel wire is certified as using nickel with a lead content that is below detection ...
A Proposition 65 Risk Evaluation of Lead in @@ Guitar Strings
Edmund Crouch, Ph.D. and Laura Green, Ph.D., D.A.B.T. Cambridge Environmental Inc. 58 Charles Street, Cambridge, MA 02141 Phone: 617-225-0810 www.CambridgeEnvironmental.com Prepared for @@
@@, 2009
©2009 Cambridge Environmental Inc. All rights reserved
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Table of Contents 1. Overview and Introduction ......................................................................................................... 2 2. Proposition 65 “No Significant Risk” dose and “Maximum Allowable Dose Level” ............... 3 3. Concentration of lead in @@ guitar strings ............................................................................... 3 3.1. Raw material specifications and measurements .................................................................. 3 3.2. Wipe test results................................................................................................................... 3 4. Initial screening evaluation ......................................................................................................... 4 5. Detailed evaluation of exposure pathways ................................................................................. 5 5.1. Amount of lead rubbed from guitar strings on to fingers .................................................... 5 5.1.1. Experimental measurements of metal transfer.............................................................. 5 5.1.2. Application to lead transfer from guitar strings............................................................ 9 5.2. Ingestion exposure to lead from guitar strings................................................................... 12 5.3. Dermal absorption exposure of lead from guitar strings ................................................... 13 5.4. Total exposure to lead from guitar strings ......................................................................... 14 5.5. Other operations claimed to result in exposure in the Notice............................................ 14 6. Conclusion ................................................................................................................................ 15 7. References................................................................................................................................. 15 1. Overview and Introduction A recent notice1 alleges that use of @@ musical guitar string products poses a significant risk of birth defects and other reproductive harm and cancer. In particular, it is implied that the presence in these products of lead and/or lead compounds would result in a dose to an average consumer and/or occupational user larger than California’s Maximum Allowable Daily Level (MADL) for reproductive toxicity and/or No Significant Risk Level (NSRL) for cancer. On its face, this claim is not credible, and cannot have been supported by any reliable data and exposure assessment. Standard wipe-test data (presented below) indicate only infinitesimal quantities of lead available on the surface of these strings, such that an average guitar player would have to lick over the entire length of such a string about 9–12 times per day, or somehow obtain an equivalent dose, in order to ingest more than the maximum allowable dose. Further exposure assessment (presented below) demonstrates that even worst-case exposures to these guitar strings do not result in any significant dose of lead, and so do not result in the alleged violation. Lead is present at low concentrations in @@ guitar strings because of the use of tin plating, bronze, and brass2 to construct those strings. Lead contamination of these materials is practically inevitable, and its concentration is controlled at sufficiently low levels by the specifications provided by its suppliers of products (wire) containing tin, bronze, or brass. As detailed below, the presence of lead in @@ guitar strings is of no toxicologic significance. 1
60-Day Notice of Violation In Compliance with California Health & Safety Code §25249.7(d), from @@ 2 The bronze and brass are not “leaded” — no lead is deliberately added; see Section 3.1.
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2. Proposition 65 “No Significant Risk” dose and “Maximum Allowable Dose Level” The Reproductive and Cancer Hazard Assessment Branch of OEHHA is the lead agency for the implementation of the Safe Drinking Water and Toxic Enforcement Act of 1986 (Proposition 65), and in that role has established no significant risk levels (NSRLs) for carcinogens and maximum allowable dose levels (MADLs) for chemicals causing reproductive toxicity. The latest available list of these levels is dated February 2009 (OEHHA, June 2009), and indicates an NSRL of 15 µg/day for lead, with higher values for several other lead compounds, and a MADL of 0.5 µg/day for lead. In assessing NSRLs for carcinogens, the relevant time frame for exposure is the long-term average, where long term is typically taken to be a 70-year lifetime.3 In assessing MADLs for chemicals causing reproductive toxicity, the relevant time frame for exposure is a 9-month average.4 In what follows, we show that even when exposures are averaged over only a single day, the MADL for lead is not exceeded. 3. Concentration of lead in @@ guitar strings 3.1. Raw material specifications and measurements The @@ guitar strings cited in the Proposition 65 notice (Footnote 1) are constructed in various ways. “Plain” strings have a steel core wire that is tin plated (about 0.3 mils thickness of tin, or 0.0003 inches), with no further treatment. Coated plain strings have a steel core that is zinc coated, with a subsequent polymer coating. The strings for lower notes (with higher gauges) have a tin-plated steel core wire wrapped with wire made from phosphor-bronze (ASTM B 159/B 159M, UNS# C51000, 95:5 copper:tin), brass (ASTM B 134/B 134M, UNS# 24000, 80:20 copper:zinc), or nickel-plated steel. For some of the wrapped strings, the bronze or brass is polymer coated. ASTM B 134/B 134M, UNS# 24000 for brass specifies a lead content
