A Toxicological Review of the Ozone NAAQS

1. A Toxicological Review of the Ozone NAAQS Michael Honeycutt, Ph.D. Director, Toxicology Division

2. Timeline

4. General Comments • Selective studies vs Weight of Evidence • EPA emphasized studies that reported positive findings (regardless of statistical significance) and relied on only a few of these to generate risk estimates rather than use a quantitative Weight of Evidence approach • Modeling • MSS model for estimating lung function decrements • Co-pollutants not considered in core analysis (potential for double-counting) • HDDM model replacing quadratic rollback • Inappropriate selection of health endpoints • Mortality should not be included • FEV1 lung function decrements without symptoms are not adverse • Misrepresentation of scientific literature • Evidence for effects at levels below current standard inconsistent • Inappropriate calculation of health risk below background ozone levels • Data below lowest measured levels in epidemiology is highly uncertain • Risk calculated for levels below those that can be controlled through regulations • Inappropriate one-size-fits-all standard given regional differences in “health effects” • Pooled (nation-wide) estimates don’t reflect this variability • Texans may not benefit, and may be harmed, by some alternatives presented

5. Contradictions EPA indicates their belief that the current NAAQS is not adequately protective but July 2013 stated There is “legitimate uncertainty” that a causal relationship exists between O3 and 8-hour exposures less than 75 ppb and that a lower standard was not necessary EPA discounts the possibility of a threshold for health effects in their calculations but elsewhere states “…clinical studies have suggested the presence of a threshold for respiratory effects…” EPA indicates their intention to consider a standard level within the range of 70-60 ppb which “could provide an appropriate degree of public health protection and would result in important improvements in protecting the health of at risk populations and lifestages” but elsewhere report ”small increases in mortality” for urban case study areas, including Houston EPA identifies children and asthmatics as sensitive subpopulations but elsewhere report Effects in children are similar enough to adults to use adult data extrapolated to children and Health effects in asthmatics vs. non-asthmatics were “virtually indistinguishable”

6. Health Endpoints Mortality Short Term Central Nervous System Effects Cardiovascular Effects Respiratory Effects* Suggestive Determinations made in ISA Likely Causal Central Nervous System Effects Respiratory Effects Cardiovascular Effects Long Term Reproductive/ Developmental Effects Endpoint used quantitatively to derive NAAQS Mortality * Includes lung function, respiratory symptoms and medication use, respiratory-related hospital admissions and emergency department visits

7. Clinical Studies • Adams, 2006 (UC Davis) • 30 healthy young adults exposed for 6.6 hours to Filtered Air (not background!), 60 ppb and 80 ppb while exercising → FEV1 measured every hour • 80 ppb statistically decreased FEV1 (5.6%) only after 6.6 hours • Scheffe post hoc test found no statistical difference between 60 ppb and Filtered Air • EPA T-test found that 2.8% difference was statistically different without correction for multiple comparisons • >20% reduction considered adverse effect • Normal daily variation in FEV1 → 5 to 17% Michael Honeycutt, Ph.D.

8. ATS/ERS 2005 • Pellegrino et al. (2005) article is a joint American Thoracic Society/European Respiratory Society publication where they say: • Changes in FEV1 correlate "poorly with symptoms and may not, by itself, accurately predict clinical severity or prognosis for individual patients." • FEV1 decrements can vary by about 5% in healthy adults daily and 15% or more yearly. • “When using percent change from baseline as the criterion, most authorities require a 12-15% increase in FEV1 and/or FVC as necessary to define a meaningful response.” • “Increments of <8% are likely to be within measurement variability.” • A <=30% decrement in FEV1 is considered a mild effect

9. Ecological Epidemiology Studies • Collect death certificates from non-accidental deaths • Time of death • Collect ozone (PM, SO2, etc.) levels (1-hr, 8-hr, 24-hr) for time periods preceding death. Repeat going back in time for 36 hours. • Correlate changes in ozone (or other pollutant) concentration with changes in mortality Michael Honeycutt, Ph.D.

10. Ambient Concentrations of Ozone

11. Personal Exposure 83.8% 38.1% 96.0% • Ambient monitors are very poor measures of actual exposure to individuals • Personal exposure is much lower than ambient concentrations of ozone 80.1% 98.4% Air Conditioning Usage Source: U.S. Energy Information Administration

12. Mortality Estimates “..the mortality risk metric is generally not responsive to meeting the existing and alternative standard levels” Current NAAQS Range of U.S. Background Range of Alternative Standards ACS Study Note: previous investigators did NOT find effect for ozone

13. Long-Term O3 and Mortality I

14. Long-Term O3and Mortality II Only for temperatures >82°F, NOT in US regions with highest ozone concentrations (Southern CA) NOR in areas with highest respiratory deaths (NE and Industrial MW).

15. Texas DataHouston (2007) No deaths due to O3 >65 ppb Changing the standard alters the number of deaths predicted to occur

18. Impact of Study Selection Nation-wide Southern California Southwest Northwest Upper Midwest Southeast Industrial Midwest Northeast No Effect Small but statistically significant Estimates could range from positive to negative Percent Increase in Total Mortality per 10 ppb Increase in 8-hour Ozone by City for June-August. The diamond represents the pooled mortality estimate. (Source: Figure 1 in Zanobetti and Schwartz, 2008a) Relative Risk (Source: Table 4 from Jerrett et al. 2009) City-specific Percent Increase in Total Mortality per 10 ppb Increase in Same-day 24-hour Ozone With and Without Adjustment for Particulate Sulfate (Source: Figure 2 from Franklin and Schwartz, 2008) Percent Increase in All-cause Mortality per 10 ppb Increase in Daily Ozone (Year-round Analysis). The raw maximum likelihood estimates (triangles) are shown together with the Bayesian estimates (circles) from Bell et al. (2004) and the regional estimates (squares). (Source: Figure 1 from Smith et al., 2009)

20. Weight of Evidence Approach

21. Policy AssessmentWill background be considered?

22. Transparency and Accuracy • In the Executive Summary of the Policy Assessment, these words do not appear: • Threshold • Uncertainty • Background

23. Questions?