Advances in Understanding Asbestos Risk Driving change in sustainable Remediation David Dangerfield

22 October, 2013

Acknowledgements

Ross McFarland, Technical Director, AECOM Australia

Ben Hardaker, Engineer, AECOM Australia

John Howell, Senior Toxicologist, Environmental Health Directorate, Health Western Australia

Understanding Asbestos Risk – In Soil

The Problem

− ASBestos In Soil (ASBINS) a significant problem in New Zealand.

− Health effects from airborne exposure have a long latency period.

− Becomes more evident with development, intensification and natural disasters.

− Solutions are often costly and involve generation of a large and costly footprint in terms of dollars and carbon.

− Challenges in applying an agreed framework to characterise risk.

International Guidance – Asbestos in Soils

− A number of jurisdictions have developed guidance internationally:

• Netherlands (RIVM).

• United States (Asbestos Framework).

• Australia (NEPM/WA).

• UK (WHO).

− The Ministry for the Environment provides a framework for adopting international guidance.

Airborne Exposure Limits

Airborne Exposure Limits

− Well established exposure levels for occupational environment.

Airborne Exposure Limits

− Well established exposure levels for occupational environment.

− NZ Workplace Exposure Standard.

Duration Concentration in air

(fibres/mL)

Chrysotile

4-hr 1.0

10 min 6.0

Amosite / Chrocidolite

4-hr 0.1

10 min 0.6

Progressing from Air to Soil

Defining Risk

- Can toxicity be described by duration and concentration in the same way we have concentrations in soil or groundwater for arsenic, benzene, benzo(a)pyrene or vinyl chloride?

- Can we trust international research?

• Data on fibre release from soil to air.

• Examination of suitable criteria.

• Development of risk matrix to rank variables that determine likelihood of exposure.

Netherlands – Swatjes/Tromp

Swartjes/Tromp, 2008.

Non-occupational Airborne Exposure Limits

a Asbestos fibre equivalents where differentiation in potency is based upon fibre length and type (amphibole and serpentine types)

Source: Ben Hardaker’s paper “Asbestos-Contaminated Soil Risk Assessment”, 30 September 2009

Jurisdiction/Body 10-6 Lifetime Cancer Risk (fibre/mL)

10-5 Lifetime Cancer Risk (fibre/mL)

10-4 Lifetime Cancer Risk (fibre/mL)

United States (IRIS, 2008)

0.000004 0.00004 0.0004

Netherlands (TNO, 2005)

0.001a - 0.1a

United Kingdom (WHO, 1988)

- 0.0005 -

Western Australia (WHO 2000)

0.0001 -

Non-occupational Exposure Limits – Air & Soil

a Asbestos fibre equivalents where differentiation in potency is based upon fibre length and type (amphibole and serpentine types)

b Based upon Netherlands air and soil threshold values for 10-6 excess lifetime cancer risk

Slide sourced from Ben Hardaker’s paper “Asbestos-Contaminated Soil Risk Assessment”, 30 September 2009

Jurisdiction/Body 10-6 Lifetime Cancer Risk (fibre/mL)

10-5 Lifetime Cancer Risk (fibre/mL)

10-4 Lifetime Cancer Risk (fibre/mL)

Asbestos in Soil Concentration (% (w/w))

United States (IRIS, 2008)

0.000004 0.00004 0.0004 -

Netherlands (TNO, 2005)

0.001a - 0.1a 0.01

United Kingdom (WHO, 1988)

- 0.0005 - 0.1 (0.001)

Western Australia (WHO 2000)

0.0001 - 0.001b

International Risk Models

Note: Site-specific conditions will determine the appropriate excess lifetime cancer risk level to be adopted

Slide adapted from Ben Hardaker’s paper “Asbestos-Contaminated Soil Risk Assessment”, 30 September 2009

Jurisdiction Risk Model Accepted Cancer Risk

Potency Factor

Chrysotile Amosite Crocidolite

United States IRIS 10-4 (1 in 10 000)

1 1 1

United Kingdom Hodgson & Darnton

10-5 (1 in 100 000)

1 100 500

Netherlands RIVM 10-6 (1 in 1 000 000)

1 10 10

Australia (NPM/WA)

WHO RIVM + 10

10-5 to 10-6 1 1 1

Establishing Soil to Air Relationship

Asbestos concentration in soil (% w/w)

0.001 0.01 0.1 1.0 10 100

Airb

orn

e a

sb

esto

s c

on

ce

ntr

atio

n

(fib

/mL

)

0.00001

0.01 0.01 0.01

0.001

0.0001

0.1

1.0

10

Swartjes/Tromp, 2008.

COMCARE Research Project, AECOM Australia

− AECOM received a research grant through the Australian Government Comcare’s Asbestos Innovation Fund to develop a field-based asbestos in soil to air migration pathway detection tool.

Developments in the Detection Limit in Soils

What are the issues?

− Achieving method detection limits (0.001% w/w).

− National Analytical Testing Authority (NATA) soon to publish/certify a draft method for soil analysis.

− Currently no lab in NZ can undertake analysis using the NATA method (500 g samples). ISO 17025 analytical protocol.

− Validating Result:

− Detection limit of asbestos in air is 0.01 fibres/mL.

− Electron Microscopy – 0.001 fibres/mL ($500/sample).

The Future?

Other Hurdles to Overcome in NZ

− How do we get consent to a more sensitive land use?

− What does a Sample Analysis and Quality Plan look like for asbestos? (How do we characterise a site in a scientifically defensible manner).

− Is there still provision to apply pragmatic, site specific solutions?

Status Quo

- Dare we progress from 1993 published: “Approaches to the assessment and management of asbestos – contaminated soil”

Imray & Neville

(<0.001% - Consultant’s Delight)

Conclusions

− Current international practice – still developing but a clear, scientifically defensible framework.

− Established methods for characterising human health risk.

− If not…….

Vexing Questions / Observations

− Is 100% clean-up of asbestos waste sustainable?

− Can our waste facilities accept low levels of asbestos?

− In Christchurch - if we had a choice between:

− 100% clean-up and disposal to a Class A Landfill facility; or

− The construction of a new hospital.

Thank You

david.dangerfield@aecom.com