Reference Dose Study Guide Questions Fully Solved.

two ways to perform non-cancer risk assessment - correct answer 1. estimate dose with exposure assessment and then compare to health based benchmark, dose response experiment -plot dose and adverse effect on graph, model response curve, getcurve model with LOAEL, NOAEL, and LD50 -benchmark→ Reference Dose 2. measure environmental concentration and then compare to standard REL (concentration benchmark, calculated for different time frames especially in air environment)→ divide dose with no effect in air by safety factors to get REL ***Difference: concentration of air at x vs. having a dose, different numbers cover different populations over different time frames hazard quotient - correct answer Concentration (EF)/REL or reference dose, potential for adverse effects of concern when hazard quotient is higher than one, means exposure exceeds reference dose, adverse health effect possible HQ= Actual Exposure Dose/RfD HQ 1 : Exposure exceeds reference dose, adverse health effects possible HQ 1: No adverse effects likely reference dose - correct answer estimate of the daily acute or chronic exposure that is likely to be without risk of adverse effects - use for noncancer risk assessment Obtain NOAEL threshold and then put in additional safety factors on (divide by these). Total uncertainty factor is usually a factor of ten for interspecies extrapolation, as well as considering children to adult conversion. RfD = NOAEL, LOAEL, or benchmark dose/ UF x MF UF=uncertainty factor (interspecies extrapolation, variability within human population, using less than chronic data, using LOAEL instead of NOAEL and MF = modifying Factor for children (1-10) Uncertainty Factors: 10= interspecies extrapolation 10= Variability within human population (IntrAspecies) 10= Using less than chronic data* 10 = Using LOAEL, instead of NOAEL *Chronic = years vs. Acute = fast, quick, short *Infections from infectious diseases= acute; Type 2 diabetes= Chronic LOAEL vs. NOAEL - correct answer ONLY use the LOAEL when you don't know the NOAEL Why is UF= 10? → This came from EPA based on engineering research a number had to be put in place and 10 worked best. Allow a certain level of contaminant that won't let people become terribly sick. REL - correct answer incorporates similar protections as Reference Dose REL= the specific chemical level in a room (Concentration) Health based benchmark dose used to environ concentration consistent with exposure at the RfD →Reference exposure level or air →Estimate exposure level in environment consistent w exposure at ref dose →Rox studies to identify enviro exp levels that unlikely to cause adverse effects →Incorporates similar protections as Rfd HQ for approach 2: →HQ= Ratio of measured enviro level (Exposure air concentration mg/m^3) / (REL mg/m^3) →Typical benchmarks : REL - acute REL - 8 hour cREL- chronic RfC- EPA reference concentration how many approaches are there in a non-cancer risk assessment? - correct answer 2 non-cancer risk assessment approach 1 - correct answer Estimate dose Compare dose to health-based benchmark (e.g., reference dose RfD) NOAEL, LOEL, LD50 non-cancer risk assessment approach 2 - correct answer Measure environmental concentration Compare environmental measurement to standard (e.g., reference level Reference Exposure Level) cancer risk assessment - correct answer non-cancer response: no effect with little exposure, more toxic effect with more exposure, get asymptomatic at top s more once really sick won't make a difference with cancer: assume linear and the intercept is zero, no threshold