Environmental Pollution Prevention & Waste Management Hierarchy

Environmental Risk assessment (ERA) components

(First part 1-4): 1) Problem definition / hazard identification -> 2 & 3 2) Hazard characterization -> 4 3) Exposure assessment -> 4 4) Risk characterization -> 5 (Second Part): 5) Risk communication -> 6 6) Risk management

Excess risk =

(Pi - P0)/(1 - P0) Pi: incidence at non-zero dose i P0: be the incidence for no dose (control)

Cancer Endpoint Descriptors. The human carcinogenic potential of a chemical is classified as:

- Likely to Be Carcinogenic to Humans - Suggestive Evidence of Carcinogenic Potential - Inadequate Information to Assess Carcinogenic Potential - Not Likely to Be Carcinogenic to Humans

Compartmental Model Approach

1) Describe system being modeled - Routes of exposure - Transport between compartments - Excretion 2) Set Goal - i.e. Dynamics (time trends) for Pb accumulation in each compartment 3) Outline approach and assumptions

Why pollution prevention?

1) Economic - Process efficiency - Cost of waste disposal/emissions - Future liability 2) Regulatory compliance 3) Environmental Stewarship

Risk assessment stages associated with EPA's IRIS

1) Hazard identification 2) Dose-response assessment (Hazard characterization)

Routes of exposure

Dermal (through skin) Inhalation (breathing) Ingestion (oral)

feed -> reactor -> product + unreacted feed -> separator -> 1) product 2) unreacted feed fed back into the original feed stream

In-process recycling

The most common cancer descriptors are:

Inhalation unit risk (IUR) Oral slope factor (OSF)

IRIS stands for:

Integrated Risk Information System

Exposure

Magnitude and length of time an organism is in contact with the hazard-causing substance or situation

RfD =

NOAEL/(FA*FH*FS*FL*FD) F's are adjustment factors for: A: extrapolation from animals to humans H: differences in human susceptibility S: data obtained from subchronic studies L: LOAEL used instead of NOAEL D: dubious or incomplete data

Genotoxic carcinogen

No safe level of exposure

Pareto Curve

Optimization of cost and waste. Includes Pareto-optimal line with feasible region and existing technology clusters above it, and the infeasible region below.

Input from environment denoted as

P

PBPK Model is and is used to:

Physiologically-Based Pharmacokinetic Model Used to relate the amount of chemical exposure to the amount of chemical found in the blood and organs at different points in time.

BMD =

PoD/UF Where: -PoD = Point of Departure for human health exposure guidelines, can be the NOAEL or the BMDL -UF = composite uncertainty factor (denominator in the NOAEL equation)

Hazard

Potential of a substance or situation to cause harm or to create adverse impacts on persons or environment

Non-Cancer Endpoint Descriptors

Reference dose (RfD) Reference concentration (RfC)

Basic premise of pollution prevention

Risk reduction!

Non-genotoxic carcinogen

Safe level (threshold) of exposure

EPA definition of pollution prevention in WM hierarchy

Source reduction -> in-process recycling

Our definition of P^2

Source reduction -> in-process recycling -> on-site (out of process recycling) -> off site recycling

Risk

The combination of the probability, or frequency, of occurrence of a defined hazard, and the magnitude of the consequences of the occurence Risk = f(Hazard, Exposure)

Benchmark Dose (BMD)

The dose that corresponds to a specific change in an adverse response compared to the response in unexposed subjects. It is determined by modeling a dose-response curve in the region of the dose-response relationship where biologically observable data are available. To take uncertainty of the data into consideration, the dose of interest is the lower 95% confidence limit (i.e., BMDL) on the BMD. On the other hand, the calculation of a NOAEL generally utilizes data that are categorized into distinct dose groups, and categorization of subjects into dose groups is an arbitrary process

mass balance

accumulation = inputs + formation - outputs - consumption

Reference Dose (RfD) (non-cancer endpoints):

an estimate of daily exposure of the human population (including sensitive subgroups), that is likely to be without an appreciable risk of deleterious effects during a lifetime. It can be derived from a NOAEL, LOAEL, or benchmark dose, with uncertainty factors generally applied to reflect limitations of the data used.

Inhalation unit risk (IUR)

an estimate of the increased cancer risk from inhalation exposure to a concentration of 1 µg/m3 for a lifetime. The IUR can be multiplied by an estimate of lifetime exposure (in µg/m3) to estimate the lifetime cancer risk.

Oral slope factor (OSF)

an estimate of the increased cancer risk from oral exposure to a dose of 1 mg/kg-day for a lifetime. The OSF can be multiplied by an estimate of lifetime exposure (in mg/kg-day) to estimate the lifetime cancer risk.

feed -> reactor -> product + waste -> separator -> 1) product 2) waste -> environment

direct release to environment

Cancer Slope Factor (CSF) (a.k.a. oral slope factor (OSF) =

excess risk/dose rate in mg/(kg-day) so units are (kg-day)/mg

compartmental mass balance subscripts

k_FROM->TO * m_FROM so if B = blood, M = marrow k_BM * m_B is the transfer rate from blood to marrow

Input to environment denoted as

k_compartment -> E * m_compartment

LOAEL

lowest observed adverse effect level

NOAEL

no observed adverse effect level

feed -> reactor -> product + waste -> separator -> 1) product 2) transport of waste -> cross site boundary -> different process -> different product

off-site recycling

feed -> reactor -> product + waste -> separator -> 1) product 2) Waste -> different process -> different product

on-site recycling (out of process)

feed -> reactor -> product + waste -> separator -> 1) product 2) waste -> landfill

secure disposal

feed -> reactor -> product + less waste

source reduction

Waste Management Hierarchy

source reduction -> in-process recycling -> on-site recycling (out of process) -> off site recycling -> waste treatment -> secure disposal -> direct release to environment

feed -> reactor -> product + waste -> separator -> 1) product 2) waste -> waste treatment -> different waste

waste treatment

Dose response curve

y = toxic response (%) x = log(dose) if toxic response % is death %: LD50 = lethal dose killing 50% of the population (occurs at a toxic response of 50%).

RfC

An estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime. It can be derived from a NOAEL, LOAEL, or benchmark concentration (these terms are defined on later pages), with uncertainty factors generally applied to reflect limitations of the data used.