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Hexavalent Chromium (Cr6) in Drinking Water

October 9, 2012. Hexavalent Chromium (Cr6) in Drinking Water. Current Status and 2013 Forecast . Ann M. Mason Senior Director 202.249.6704 ann_mason @ americanchemistry.com. Chromium. Chromium occurs naturally in the environment and exists in multiple forms (valences) Cr3 is natural

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Hexavalent Chromium (Cr6) in Drinking Water

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  1. October 9, 2012 Hexavalent Chromium (Cr6)in Drinking Water • Current Status and 2013 Forecast Ann M. Mason Senior Director 202.249.6704 ann_mason @ americanchemistry.com

  2. Chromium • Chromiumoccurs naturally in the environment and exists in multiple forms (valences) • Cr3 is natural • Cr6 is both manmadeAND occurs naturally at low levels Cr6 is present in US source waters used for drinking (av. range 1-5 ppb) 2. Natural mechanisms in body detoxify Cr6 to benign Cr3

  3. Cr6 in Drinking Water Has Been Regulated Since 1946 US Public Health Service Drinking Water Standard (50 ppb Cr6) 1962 US PHS reaffirmed 50 ppb Cr6 standard EPA National Interim Drinking Water Standard (50 ppb total Cr) EPA set Maximum Contaminant Level at 100 ppb total Cr; MCL assumes 100% is Cr6 201X CA revise state MCL; EPA revise Federal MCL?

  4. IRIS Assessment EPA restarted development of Cr6 IRIS assessment (announcement Feb 2012) Respond to EPA’s peer review comments Allows consideration of Mode of Action and Pharmacokinetic research findings Assessment covers oral & inhalation exposures Expect draft for public review ~April-June 2013 Expect another EPA peer review

  5. 200,000 160,000 120,000 80,000 40,000 Comparison of Exposure Levels Parts per Billion (ppb or ug/L) 5,000 4,000 3,000 2,000 1,000 0 No observed effects US Federal CA Highest Dose Lowest Dose CA 95th Percentile Cr6 Drinking Water Concentration Total Cr National Drinking Water Standard (MCL) NTP Cr6 levels Note: 1 µg/L = 1 part per billion (ppb)

  6. Cr6 MOA Research Project Addresses EPA-identified data gaps for Cr6 with studies following EPA Guidance Extends NTP study to show WHY tumors occur in GI tract of mice at high doses upon prolonged exposure Provides critical information on the differences between rodents and humans with regard to internal dose Provides EPA with data at low doses

  7. Research Finding 1: There are doses of Cr6 in drinking water where no toxicity was observed At typical drinking water doses, Cr6 is detoxified rapidly in the stomach Any residual Cr6 that moves into the small intestine is at low levels not sufficient to cause toxicity

  8. Stomach Research Finding 2: Tumor responses at high doses do not predict tumor responses at drinking water levels High doses in the 2008 NTP study exceeded the natural capacity to detoxify Cr6 by conversion to non-toxic Cr3 Excess Cr6 can ‘spill’ from stomach into the small intestine and damage cells of the intestinal villi Small Intestine Large Intestine

  9. Research Finding 3: Cr6 acts by a damage / healing processin the small intestine At the highNTP drinking water levels, the prolonged exposure causes: Cycles of tissue damage and healing, Regeneration of new cells at an accelerated rate (damage and repair process), Leading to repair fatigue & irreparable damage causing tumor formation Tumors in intestine not caused by direct DNA damage

  10. Research Findings –The Bottom Line: There is a threshold for effects in the small intestine Cr6 acts by a damage / healing processin the small intestine Tumors in small intestine are not by caused by direct DNA damage, i.e., not mutagenic Tumors in oral cavity still under study Risk Assessment paper will be submitted to peer review journal soon.

  11. Current Status & Forecast 2013 Research: Complete research & manuscript addressing oral tumors in rats Continue sharing research findings with EPA10 of 15 papers are in peer reviewed journals; rest to come shortly EPA modelers working with PBPK data and model EPA IRIS: EPA developing draft Cr6 Assessment- - IRIS Track--draft Cr6 assessment (April -June 2013) for public review& comment 3. State legislation, federal politics & media stories 4. Regulations: Expect CA draft state MCL released ~Summer 2013 for public comment

  12. Input to Water Regulations Science: Research suggests Cr6 not mutagenic in small intestine Supports peer review comments to EPA: “threshold carcinogen” Treatment Technologies (AWWA/WRF Research): Reduction/Coagulation/Filtration (RCF) RCF with microfiltration Anion Exchange (both weak base and strong base) Cost: WRF Preliminary (1Q 2012):* For an MCL of 10ppb Cr6: ~ $4.7 billion in capital costs (national) ~ $1.1 billion in annual costs nationally 4. Regulations: Expect CA draft state MCL released ~Summer 2013 for public comment EPA Federal MCL ?? *AWWA/WRF published preliminary cost and treatment data in April/June 2012; AWWA is refining cost data for publication in late 2012-2013

  13. What can PMI do? Communicate key messages Research indicates: Threshold for effects and Small intestine tumors are caused by repeated wound and heal processes not DNA damage EPA should include MOA findings in EPA assessment and replace default assumptions with data Federal and state MCLs should include MOA findings and AWWA treatment and cost information. Engage politically Congress & state legislators, as appropriate Support broader IRIS programmatic reform Report Cr6 status: science, IRIS schedule Water providers

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