# Risk Charact erizat ion **1** U.S. Environmental Pr otection Agency Thomas St eeg er

, Ph.D . Environmental F ate and Effects Division Office of P es ticide Pr ograms

# Risk Charact erizat ion • Over view • Ro le within the risk assessmen t pr ocess • Integr ation of multiple lines of evidence • Articulation of risk assessmen t assumptions, limitations, and uncert ain ties U.S. Environmental Pr otection Agency **2** uncert ain ties

# Risk Charact erizat ion • 

### The risk charact eriz ation pr ocess and re sults should be: • **Tr anspar** **en t**  -- assessmen t process is e xplicit U.S. Environmental Pr otection Agency **3**

• **Clear --**  assessmen t itself is free from obscure language and is easy to understand. • **Consist en**  **t --**  assessmen t followed appropriate Agency guidelines. • **Re asonable**  **--** assessmen t is based on sound judgment.

# Risk Charact erizat ion • 

### Tw o Major Components U.S. Environmental Pr otection Agency **4**

# Risk Estima tion • 

### Compar e e xposur e and effects dat a • Po in t es timate - based risk quotient (RQ ) method • Dis tribution - based pr obabilis tic assessmen t • 

### Consideration of in te grated e xposur e and e ffects dat a U.S. Environmental Pr otection Agency **5**

• 

### Consideration of in te grated e xposur e and e ffects dat a in con tex t of LOC ’s • 

### St ate potential fo r risk

# Risk Estima tion U.S. Environmental Pr otection Agency **6** 

### • Deriving Acute and Chr onic Risk Quotien t (RQ ) Values • Consis te ntw ith pr ocess used for other tax a 

### . • Risk as a function of e xposur e and t ox icity as a function of e e and t • RQ= Es timate Exposur e Concen tr ation/T ox icity Endpoin t

# Risk Estima tion U.S. Environmental Pr otection Agency **7**

# Risk Estima tion U.S. Environmental Pr otection Agency **8**

# Risk Estima tion • Po in t estimate - based RQs ar e compar ed t o Levels of Concern (LOCs) • Lev els of Concern (LOCs) based on: • His toric default pr obit dose - re sponse slope for other tax a of 4.5 • Analysis of honey bee adult acute contact and acute or al to xicity pr obit U.S. Environmental Pr otection Agency **9**

• Analysis of honey bee adult acute contact and acute or al to xicity pr obit dose - re sponse • Contact slope: mean=3.93 • Oral slope: mean= 3.40 • Individual E ffe ct Chance Model (IEC)

# Risk Estima tion U.S. Environmental Pr otection Agency **10** 

### • Levels of Concern (LOCs) based on: • Assuming median slope of 3.2 and 10% mortality • LO C fo r acut e risk set to 0.4. 

### • LO C for chr onic risk set t o 1.0 • Based on comparison of peak EEC to NOAEC

# Risk Estima tion U.S. Environmental Pr otection Agency **11**

# Risk Description • 

### In te rpr et ation of risks based on assessmen t endpoin ts • Eva luate lines of evidence supporting or r efuting risk es timates U.S. Environmental Pr otection Agency **12**

• Interpr et relev ance of lines of evidence t o assessmen t endpoin ts

# Risk Description • Scr eening - lev el (Tier I) RQ va lues • Po ssible r efinemen ts in Tier I RQ v alues Tier II Semi - field s tudies (whole colon y) U.S. Environmental Pr otection Agency **13**

• Tier II Semi - field s tudies (whole colon y) • Tier III Full - field s tudies (whole colon y) • Other scien tifically re lev an t information

# Risk Description • Es ta blished thr ough the pr ocess of integr ating a va ilable information and its r elev ancy to assessment endpoints. • Mor e than simply a comparison of risk quotients to lev els of concern. U.S. Environmental Pr otection Agency **14**

• Both quan tit ative and qualitative information supporting or ref uting risk finding. • As additional lines of evidence become clear , the pr oblem fo rmulation, including the conceptual model, ar e r efined.

# Risk Description • 

### Eva luation of lines of evidence • **ADE QU**  **AC Y**  **AND QU ALITY OF D** **ATA** Degr ee and type of v ariability and uncert ain ty U.S. Environmental Pr otection Agency **15**

• Degr ee and type of v ariability and uncert ain ty • Re lationship of evidence to risk assessment questions

# Adequacy and Quality of Da ta U.S. Environmental Pr otection Agency **16**
• 

### We re dat a quality objectiv es (and guidelines) adher ed t o? • What assumptions wer e made in ligh t of data g aps? • What limitations does the use of supplemen ta l data put

16 • What limitations does the use of supplemen ta l data put on the ability to assess risk fr om this pes ticide? • 

### We re e xperimen ta l designs appr opriate to answer ques tions posed in pr oblem fo rmulation?

# Risk Description • 

### Eva luation of lines of evidence • Adequacy and quality of data U.S. Environmental Pr otection Agency **17**

• **DE GREE**  **AND TYPE OF V ARIABILITY** 

**/UNCERT AINTY**  • Re lationship of evidence to risk assessment questions

## Degree and Ty pe of Uncertain ty- Va riability
• Va riability ex is ts in char act eris tics such as ecological effects and en vir onmen ta l fa te U.S. Environmental Pr otection Agency **18**

• Assessmen ts should account for v ariability in dose - re sponse re lationships

# Risk Description • 

### Eva luation of lines of evidence • Adequacy and quality of data U.S. Environmental Pr otection Agency **19**

• Degr ee and type of v ariability and uncert ain ty • **RELA TIONSHIP**  **OF EVIDENCE T O RISK ASSESSMENT** 

# Risk Description • 

### Re lationship of E vidence to Risk Assessmen t • Put the risk in the conte xt of: • Previous OPP decisions on similar pes ticides U.S. Environmental Pr otection Agency **20**

• Previous OPP decisions on similar pes ticides • Previous Agency decisions, if applicable • Risk assessments performed by other orga niz at ions • Exis ting pr ogr am policies and decisions

# Risk Description • 

### Re lationship of E vidence to Risk Assessmen t • Significance of surr og ate species to other s in class • Discussion of open liter atur e - deriv ed fr om ECOTOX U.S. Environmental Pr otection Agency **21**

• • Consider ation of sensitiv e ecosyste ms and orga nisms • Consider ation of effects not r eflected in data ( e.g ., sublethal effects or inhalation e xposur e)

# Risk Description • 

### Re lationship of E vidence to Risk Assessmen t • Adv er sity U.S. Environmental Pr otection Agency **22**

• Na tur e and intensity of effects • Te mpor al and spatial scale • Re covery potential

# Risk Charact erizat ion

Ques tions? U.S. Environmental Pr otection Agency **23**