Community Exposures to Lead (Pb): Health Evalua<on Updates and Issues

Transcription

1 Community Exposures to Lead (Pb): Health Evalua<on Updates and Issues Lynn Wilder Ph.D. Associate Director for Science, Division of Community Health Inves9ga9ons, ATSDR 9 th Annual Georgia Environmental Health Conference Session 4 GeBng the Lead Out Jekyll Island (GA) Conven9on Center August 21, 2014 The findings and conclusions in this presentation have not been formally disseminated by the Centers for Disease Control and Prevention/Agency for Toxic Substances and Disease Registry and should not be construed to represent any agency determination or policy Agency for Toxic Substances and Disease Registry Division of Community Health Inves9ga9ons

2 Presenta<on Outline The past (pre- 2012) The present The future

3 The Past (Pre- 2012) CDC blood lead level (BLL) of concern was 10 µg/dl Children 6 years of age Values 10 µg/dl initated re-testing and home visits EPA s Integrated Exposure Uptake Biokine<c (IEUBK) model predicted 400 ppm lead in soil resulted in < 95% of children 0 < 7 years of age with BLL < 10 µg/dl Model validated with environmental and BLL study results Model assumes 7 days/week soil lead exposure for a year (minimum) 400 ppm became the site screening value for contaminated soil in residential areas Lead soil values > 400 ppm typically initiated cleanup actions

4 The Present (Since 2012) CDC Adopted new blood lead reference level of 5 µg/dl Based on the 97.5th percentile of the National Health and Nutrition Examination Survey (NHANES) s blood lead distribution in children 6 years of age May change every 4 years (based on most recent NHANES) Children at or above reference value require follow-up and retesting No safe blood lead level in children has been identified Even low levels of lead in blood have been shown to affect IQ, ability to pay attention, and academic achievement Effects of lead exposure cannot be corrected with medical treatment Not changed Chelation therapy be considered when a child has a blood lead test result to 45 micrograms per deciliter

5 The Present (Since 2012) EPA Using IEUBK with new CDC BLL reference value Soil lead level ppm to achieve a BLL of 5 μg/dl What to do? Not feasible to ini9ate cleanup ac9ons using new es9mated screening value

6 ATSDR The Present (Since 2012) Soil lead screening value ppm IEUBK lead model may not sufficiently protect young children using default scenario (0-7 years) Pursuing PBPK models with different exposure frequencies and durations < 7 days/week < 1 year Various scenarios (daycare, living in snow-prone regions, etc.) % > 5 µg/dl % Blood Lead > 5 µg/dl (IEUBK) Year average 0-7 yrs

7 The Present (Since 2012) ATSDR (cont d) Less focus on: Bright line lead concentration IEUBK model results Emphasis on: Preventing exposures from any source (no known safe level of exposure) Identifying community risk factors (e.g., age of housing, poverty, race) Describing the distribution of modeled blood lead values in relation to NHANES Educating

8 The Future Con<nued ATSDR and EPA coordina<on New reference values over <me require a different approach to site evalua<ons More research Intermittent vs. chronic exposure Peak vs. average BLL Older children and adults New PBPK model development and validation

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10 References CDC web page: h`p:// ACCLPP * recommenda<ons h`p:// NTP Monograph on Health Effects of Low- level Lead (June 2012) * Advisory Committee On Childhood Lead Poisoning Prevention (ACCLPP)

11 Ques<ons/Discussion For more informa<on please contact Agency for Toxic Substances and Disease Registry 4770 Buford Hwy, NE Chamblee, GA Telephone: CDC- INFO ( )/TTY: Visit: Contact CDC at: CDC- INFO or The findings and conclusions in this report are those of the authors and do not necessarily represent the official posi9on of the Centers for Disease Control and Preven9on. Agency for Toxic Substances and Disease Registry Division of Community Health Inves9ga9ons