1. Who are the worst toxic polluters
Who are the worst toxic polluters? Human Toxicity Potentials for Life Cycle Assessment and Screening of Manufacturing Emissions
Edgar Hertwich Industrial Ecology Programme
Norwegian University of Science and Technology
N-7491 Trondheim, Norway
Sarah Mateles, Bill Pease, Tom McKone
Berkeley, California

2. Overview
SETAC Task Force on Toxicity in LCA Ranking & Scoring Toxic equivalency potentials Site-specific risk assessment
The Human Toxicity Potential
CalTOX and it use for Potential Dose calculations
Alternative modeling approaches
Uncertainty analysis of the potential dose
Application to the U.S. Toxics Release Inventory:
chemicals
manufacturing plants & industry sectors
Conclusions

3. SETAC Working Group on Life Cycle Impact Assessment
Different levels of sophistication:
Ranking and Scoring: Ordinal scoring of those attributes considered important (e.g. on a scale of 1-5; toxicity, bioconcentration, persistence). Cannot combined with emission amounts; not useful for LCA.
Toxic equivalency potentials: Cardinal indicators of toxicity combing toxic potency from animal tests or epidemiological studies with models of source-to-dose relationships. Models represent generic "evaluative" environments and not the situation at the release site. Population density often neglected.
Risk assessment: Site-specific modeling of exposure. Local conditions are taken into account, including characteristics of environment and population to estimate the number of people exposed over safe level or even disease incidence.
Accuracy, sophistication
Ease of application

4. Different methods, different evaluation principles
stressor
Benzene emissions
insult
 C6H6 concentration
stress
C6H6 exposure
consequence
leukemia
HTP
value lost
YLL, morbidity, suffering
DALY
GWP: based on a physical measure (IR radiation integrated over 20/100/500 yrs). Limited uncertainty, models relatively easy to validate.
Economic Damage Indicator: based on functional relationship between temperature (and speed T increase) and damage
Value choices:
how to treat time
which depth of analysis to choose
Impact chain acc. To Holdren (1980)
Human health impact chain
Guinée & Heijungs 1993
Hofstetter (1998)
Hertwich et al., J. Ind. Ecol. 4(1)

5. How do we best inform decisions?
A large number of chemicals are potentially dangerous, but we know very little about them. About half of the high-production volume chemicals lack basic toxicity tests needed to determine their safety.
Tradeoff between number of chemicals covered by a system and degree of detail the system can address is important. How much of the overall risk do we include in the assessment?

7. SETAC Working Group on Life Cycle Impact Assessment
General form:
Match fate&exposure indicator to toxicity indicator Humans: release -> presented dose -> dose-response curve Aquatic ecosystems: release -> concentration -> concentration-response curve
Generic indicators should be developed to account for all emissions recorded in an LCA. Investigation of site-dependent aspects should focus on those releases found to be important in the generic assessment. Concern: data on release sites; additional effort required.
Indicator score
Effect factor (toxicity)
Emissions (kg)
Fate factor

8. The Human Toxicity Potential
PD … Potential Dose per 1kg/d emissions of chemical i to environmental compartment j
q1* … cancer potency (for carcinogens) or inverse of RfD, RfC (for non-carcinogenic effects)
ref … reference compound (benzene, toluene)

9. Exposure = Sources, Transport, & Contact

10. CalTOX: Multimedia Fate and Exposure Model
Water
Sediment
Surface soil
Air
Root-zone soil
Roots
Leaves
Deep soil
Gases
Particles
Uniform concentration & equilibrium in each compartment, steady state mass balance among compartments.

11. Exposure Histogram (TCDD)

12. Significant differences between air and surface water emissions for some chemicals due to exposure-route-dependent toxicity factors, different partitioning behavior.

13. Little correlation between toxicity and potential dose:
it is important to assess both!!

14. The Toxics Release Inventory
Created in response to Bhopal, the TRI contains emissions estimates for 600 different pollutants from manufacturing facilities, power plants, smelters etc.
Mandatory reporting
Credited with success in pollution reductions, extended.
US EPA reports emissions as raw data. Environmental Defense provides data with interpretation aids: information on toxic risks, rankings, exact location etc.

15. Application of HTP: www.Scorecard.org
1998 TRI Pollution Releases Ranked by Ozone Depleting Potential
Top Ranked Ozone Depleting Chemical:
dichlorodifluoromethane
List chemicals or facilities contributing to ozone depletion
1998 TRI Pollution Releases Ranked by Potential Human Health Risks
Top Ranked Cancer Risk:
arsenic (organic or inorganic compounds)
List chemicals or facilities contributing to cancer risk
Top Ranked Noncancer Risk:
lead compounds
List chemicals or facilities contributing to noncancer risk
Example text, Illinois

16. Rankings of carcinogens
A small number of chemicals is responsible for almost all the weighted emissions.

17. Ranking of non-carcinogens; Lbs of toluene equivalents
Basis: 1998

18. Toxic Pollution by Industry Sector

19. The Dirty Dozen

20. Conclusions
The Human Toxicity Potential (HTP) is a powerful tool for comparing toxic emissions from different facilities and life-cycle stages.
HTP is based on state-of-the-art chemical fate and exposure modeling and risk assessment values (toxicity indicators) used in chemical regulation
HTP does not take into account the number of people exposed or differences in the local environment
With Environmental Defense's Scorecard project, HTP contributed to improving public information about environmental risks.
Smelting, mining, electrical power plants, and chemical industry are the most polluting industrial sectors (by far). Renewed effort in addressing these emissions is required.
TRI does not yet include PM2.5, NOx, SO2.