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Measures as amended, taking into account amendments up to National Environment Protection (Assessment of Site Contamination) Amendment Measure 2013 (No. 1)
Administered by: Agriculture, Water and the Environment
Registered 03 Jun 2013
Start Date 16 May 2013

Commonwealth Coat of Arms

National Environment Protection (Assessment of Site Contamination) Measure 1999

as amended

made under section 14(1) of the

National Environment Protection Council Act 1994 (Cwlth), the National Environment Protection Council (New South Wales) Act 1995 (NSW), the National Environment Protection Council (Victoria) Act 1995 (Vic), the National Environment Protection Council (Queensland) Act 1994 (Qld), the National Environment Protection Council (Western Australia) Act 1996 (WA), the National Environment Protection Council (South Australia) Act 1995 (SA), the National Environment Protection Council (Tasmania) Act 1995 (Tas), the National Environment Protection Council Act 1994 (ACT) and the National Environment Protection Council (Northern Territory) Act 1994 (NT)

Compilation start date:                     16 May 2013

Includes amendments up to:            National Environment Protection (Assessment of Site Contamination) Amendment Measure 2013 (No. 1)

This compilation has been split into 22 volumes

Volume 1:       sections 1-6, Schedules A and B

Volume 2:       Schedule B1

Volume 3:       Schedule B2

Volume 4:       Schedule B3

Volume 5:       Schedule B4

Volume 6:       Schedule B5a

Volume 7:       Schedule B5b

Volume 8:       Schedule B5c

Volume 9:       Schedule B6

Volume 10:     Schedule B7 - Appendix 1

Volume 11:     Schedule B7 - Appendix 2

Volume 12:     Schedule B7 - Appendix 3

Volume 13:     Schedule B7 - Appendix 4

Volume 14:     Schedule B7 - Appendix 5

Volume 15:     Schedule B7 - Appendix 6

Volume 16:     Schedule B7 - Appendix B

Volume 17:     Schedule B7 - Appendix C

Volume 18:     Schedule B7 - Appendix D

Volume 19:     Schedule B7

Volume 20:     Schedule B8

Volume 21:     Schedule B9

Volume 22:     Endnotes

 

Each volume has its own contents

 

 

 

About this compilation

The compiled instrument

This is a compilation of the National Environment Protection (Assessment of Site Contamination) Measure 1999 as amended and in force on 16 May 2013. It includes any amendment affecting the compiled instrument to that date.

This compilation was prepared on 22 May 2013.

The notes at the end of this compilation (the endnotes) include information about amending Acts and instruments and the amendment history of each amended provision.

Uncommenced provisions and amendments

If a provision of the compiled instrument is affected by an uncommenced amendment, the text of the uncommenced amendment is set out in the endnotes.

Application, saving and transitional provisions for amendments

If the operation of an amendment is affected by an application, saving or transitional provision, the provision is identified in the endnotes.

Modifications

If a provision of the compiled instrument is affected by a textual modification that is in force, the text of the modifying provision is set out in the endnotes.

Provisions ceasing to have effect

If a provision of the compiled instrument has expired or otherwise ceased to have effect in accordance with a provision of the instrument, details of the provision are set out in the endnotes.

 

 

  

  

  


 

National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of

Schedule B7

GUIDELINE ON

Derivation of Health-Based
Investigation Levels

 


Explanatory note
The following guideline provides general guidance in relation to investigation levels for soil, soil vapour and groundwater in the assessment of site contamination.

This Schedule forms part of the National Environment Protection (Assessment of Site Contamination) Measure 1999 and should be read in conjunction with that document, which includes a policy framework and assessment of site contamination flowchart.

The original Schedules B7a and B7b to the National Environment Protection (Assessment of Site Contamination) Measure 1999 have been repealed and replaced by this document.

The National Environment Protection Council (NEPC) acknowledges the contribution of the National Health and Medical Research Council and enRiskS to the development of this Schedule.

 

 


Contents
Derivation of health-based investigation levels
                                                                                       Page

1                             Introduction                                                    1

1.1             Background                                                                                1

1.2             Purpose of HILs                                                                         1

1.3             Interpretation and use of the HILs                                           2

1.3.1                Limitations on the use of the HILs                                  2

1.3.2                What does ‘exceedence’ of an HIL mean?                      2

1.4             Principles and methodology for generating the HILs             3

1.5             Objectives                                                                                    5

2                             Presentation of the health-based investigation
levels                                                               
6

2.1             Stockholm Convention                                                               6

2.2             Summary of HILs                                                                       7

2.2.1                Laboratory level of reporting                                         7

2.2.2                Polycyclic aromatic hydrocarbons                                  7

2.2.3                Toxicity surrogate approach                                           7

2.2.4                Inorganic mercury                                                           8

2.2.5                PCBs                                                                                 8

2.2.6                Interim HILs for volatile organic chlorinated
compounds                                                                      
8

2.2.7                Free cyanide                                                                     8

2.2.8                Home-grown produce                                                      9

3                             Generic land use scenarios                            13

3.1             Introduction                                                                              13

3.2             Description of the generic land use scenarios                         14

3.2.1                HIL A values – residential land use scenario with
garden/accessible soil                                                    
14

3.2.2                HIL B values - residential scenario with minimal
opportunities for soil access                                         
15

3.2.3                HIL C values - public open space scenario                  16

3.2.4                HIL D values - commercial/ industrial scenario           17

3.2.5                Sensitive populations                                                      18

3.3             Exposure pathways                                                                  19

3.4             Application of the HILs to alternative land use scenarios     20

4                             Toxicity assessment                                        21

4.1             Sources of toxicity data                                                            21

4.2             Approach for carcinogenic contaminants                              21

4.3             Toxicity approach for dermal exposure                                 21

4.4             Background exposure and contribution of soil to total
exposure                                                                                   
22

4.5             Bioavailability and bioaccessibility                                          22

4.6             Speciation                                                                                  23

4.7             Toxicity of groups of substances                                             24

5                             Exposure assessment                                     25

5.1             Exposure pathways                                                                  25

5.2             General human characteristics applied in the derivation
of the HILs                                                                               
25

5.2.1                Body weight                                                                   25

5.2.2                Exposure duration and frequency                                 26

5.2.3                Averaging time                                                              26

5.3             Pathway-specific exposure assumptions                                 28

5.3.1                Incidental ingestion of surface soil and dust                 28

5.3.2                Dermal contact with surface soil and dust particulates 29

5.3.3                Indoor and outdoor inhalation of dust                          30

5.3.4                Indoor and outdoor inhalation of vapours derived
from soil                                                                        
31

5.3.5                Consumption of home-grown produce                          32

5.4             Blood lead modelling                                                                34

5.4.1                Modelling adult exposures to lead                                 34

5.4.2                Modelling child exposures to lead                                 34

5.4.3                Bioavailability and bioaccessibility of lead                   35

5.5             Vapour assessment                                                                   35

5.5.1                Introduction                                                                   35

5.5.2                Indoor exposures                                                           36

5.5.3                Outdoor exposures                                                        38

6                             Risk characterisation - how the HILs were
generated                                                      
39

6.1             Risk characterisation and calculation of HILs                       39

6.2             Target risk levels                                                                       39

6.3             Presentation of HILs                                                                39

6.4             Uncertainty and sensitivity analysis                                        39

6.4.1                HIL uncertainty analysis                                               39

6.5             HIL sensitivity analysis                                                             40

6.5.1                Soil fraction of organic carbon                                     41

6.5.2                Vapour intrusion rate                                                    41

7                             Bibliography                                                 42

8                             Glossary                                                         46

9                             Shortened forms                                            52

 

Appendix A Derivation of HILs and interim HILs

Appendix B Equations for derivation of HILs and interim HILs

Appendix C Calculations for HILs and interim HILs for generic land uses

Appendix D Blood lead model assumptions

 

 


1                  Introduction

1.1              Background

This document presents the health investigation levels (HILs) for soil and describes their derivation. Schedules B7a and B7b to the National Environment Protection (Assessment of Site Contamination) Measure 1999 (the NEPM) have been updated and combined in this revised Schedule B7.

 

A review of the NEPM (NEPC 1999) was carried out during 2005-2006 at the request of the National Environment Protection Council (NEPC). The review recommended changes to improve the effectiveness and efficiency of the NEPM by addressing technical, scientific and health risk issues raised by site assessors, consultants, land developers, auditors and the public (NEPC 2006).

 

The recommendations from the NEPM review that relate to the HILs are as follows:

·         Recommendation 5 — revise existing HILs in light of current knowledge

·         Recommendation 6 — derive additional HILs for priority substances

·         Recommendation 7 — develop guidance to further clarify the use of HILs to counter their inappropriate use as remediation (i.e. clean-up) criteria

·         Recommendation 8 — develop HILs for a priority list of carcinogenic contaminants

·         Recommendation 15 — develop HILs, in a prioritised fashion, for all non-dioxin persistent organic pollutants (POPs) not addressed in the original NEPM (NEPC 1999).

The requirement for additional HILs was also discussed at the 5th National Workshop on the Assessment of Site Contamination (NEPC 2003), at which some new HILs were proposed, and a list of possible candidate substances was produced.

 

This revised Schedule B7 addresses the findings of the NEPM review process. It presents an expanded list of HILs in accordance with the above recommendations, and sets out the revised and updated methodology adopted to derive the HILs. The methodology presented here is also applicable to site-specific health risk assessment. Further guidance on site-specific health risk assessment is provided in Schedule B4 Guideline on site-specific health risk assessment methodology.

1.2              Purpose of HILs

The HILs (including interim HILs) are scientific, risk-based guidance levels (or Tier 1 criteria) designed to be used in the first stage of an assessment of potential risks to human health from chronic exposure to contaminants. The HILs are referred to by regulators, auditors and consultants in the initial process of assessing site soil contamination.

 

HILs are defined as the concentration of a contaminant above which further appropriate investigation and evaluation will be required.

 

Levels in excess of the HILs do not imply unacceptability or that a significant health risk is likely to be present. Similarly, levels below the HILs do not necessarily imply acceptability or that a health risk is not likely to be present, particularly if more sensitive populations[1] are present or the assumptions for land use scenarios are not appropriate.

 

The HILs are designed to be used to define the contaminants that require a more detailed (Tier 2) risk assessment. The tiered process of health risk assessment into which the HILs fit is described in detail in Schedule B4.

 

The HILs have been designed to be protective of the health of most people who could potentially be exposed to soil contaminants under four broad land use categories. For people within sensitive populations; for example, the immunosuppressed, those with pre-existing illness, or those with pica behaviour, the HILs may not be sufficiently protective of health. These issues would need to be addressed in a site-specific assessment.

 

The HILs have been developed under four broad land use categories (discussed in detail in Section 3). To estimate potential human exposure to soil contaminants within each of these land use categories, generic assumptions have been made about the environment, human behaviour, the physicochemical characteristics of contaminants, and the fate and transport of contaminants in soil (refer to Sections 3 and 4). The HILs have been derived by comparing estimated exposures with toxicity criteria using a quantitative modelling process. The toxicity criteria for all of the contaminants addressed in this guidance are outlined in the toxicity profiles included in Appendix A.

 

As indicated above, the HILs are not intended to be used as clean-up levels for contaminated sites. The decision on whether clean-up is required and, if so, to what extent, should be based on site-specific assessment and risk management options. Health risk assessment is one aspect of making the decision, with other considerations such as practicality, timescale, effectiveness and cost also being important.

1.3              Interpretation and use of the HILs

1.3.1        Limitations on the use of the HILs

The information in this Schedule is designed to assist risk assessors in the application of HILs to assess the potential risks posed to human health by soil contaminants, in a preliminary site assessment. Critical to this judgement is whether the conceptual site model (CSM) used to describe any of the generic land use categories is representative of the site in question.

 

The CSM for some sites may identify other potential risks from site contamination that are not covered by the HILs, including:

·         additional sources of contamination, for example, in groundwater or surface water

·         short-term acute health risks, such as explosive or asphyxiation risks associated with the build-up of gases in a confined space, or the skin irritation risk associated with direct dermal contact with some soil contaminants

·         leaching of soil contamination into groundwater

·         health risks associated with the off-site migration of contaminants, for example, the contamination of potable groundwater supplies

·         health risks associated with exposure to soil contaminant vapours within a basement structure, or a structure where preferential pathways are present

·         other land use scenarios that are not adequately addressed in any of the generic land use scenarios (e.g. agricultural land)

·         consideration of aesthetic issues

·         risks to ecological receptors, for example, terrestrial or aquatic species.

1.3.2        What does ‘exceedence’ of an HIL mean?

The potential for soil contaminant concentrations to vary significantly over a site means that a representative number of samples are required for an adequate understanding of the site. Recommendations regarding the sampling requirements for contaminated sites are described in Schedule B2.

 

Subject to the condition that site users are not identified as belonging to sensitive sub-populations, a site may be considered suitable for an intended land use provided that contaminant concentrations are less than the relevant HILs, with evidence from a sufficient number of samples and a spatially representative sampling design. In a situation where contaminant concentrations in some samples at a site exceed the HILs, statistical analysis may assist in the description and assessment of soil data in relation to the HILs.

 

HILs should only be used where there has been adequate characterisation of a site (that is, appropriate representative sampling has been carried out).

 

As a minimum, the maximum or 95% UCL should be compared to the HILs. However, where there is sufficient data and it is appropriate for the exposure being evaluated, the arithmetic mean (or geometric mean in the case of a log normal distribution) should also be compared to the HILs. The relevance of localised elevated values should be considered and should not be obscured by consideration only of the relevant mean of the results. The results should meet the following criteria:

·         the standard deviation (SD)of the results needs to be less than 50% of the HIL; and

·         no single value exceed 250% of the HIL.

However no single summary statistic will fully characterise a site and appropriate consideration of relevant statistical measurements should be used in the data evaluation process and iterative development of the CSM (refer to Schedule B2, Section 4). The preferred approach is to examine a range of summary statistics including the contaminant range, median, arithmetic/geometric mean, standard deviation and 95% UCL. Further information is provided in Section 11 of Schedule B2.

 

The application of interim HILs also needs to take into consideration soil vapour data. This data should be evaluated in order for it to be used in the appropriate exposure scenario at a site. The relevance of conducting statistical tests (other than the arithmetic mean) should be evaluated for soil vapour data. Where data is limited or it is not relevant (for the purpose of assessing exposure) to conduct statistical analysis, the maximum soil vapour concentration can be compared against the interim HIL.

 

Exceedence of the HILs does not automatically imply that quantitative modelling at Tier 2 risk assessment stage is warranted. Similarly, concentrations less than that of the HILs do not necessarily imply that a Tier 2 risk assessment stage is not warranted. As already mentioned, HILs are not intended to indicate a clear demarcation between ‘acceptable’ and ‘unacceptable’ soil contaminant levels.

 

The decision to proceed or not to proceed with additional data collection and risk assessment should always be considered with reference to the site-specific exposure pathways, the consequences of exposure, and the characteristics of the exposed population (i.e. site-users).

1.4              Principles and methodology for generating the HILs

The derivation of HILs follows the same five-step process central to Australian risk assessment practice as outlined in Schedule B4 and enHealth (2012a).

 

Fundamentally, the HILs have been derived as scientifically-based, generic criteria designed to be used in the first stage of an assessment of potential risks to human health from chronic exposures to contaminants. The underlying principles/considerations adopted in deriving the HILs are as follows:

·         each HIL should embody a margin of safety such that there is no appreciable risk for exposures for the relevant scenarios, A–D. This has been undertaken on the basis of available scientific information to March 2012 (including toxicity reference values that are generally based on the known most sensitive significant toxicological effects).

·         where an HIL has been formerly established (NEPC 1999) and scientific information is available that supports the revision of the HIL (to a higher or lower value), then the HIL has been revised. However a policy decision has been applied such that where the scientific information only supports a minor revision of the HIL by less than approximately 20%, or the new scientific data is not adequately robust, the existing HIL has been retained (with no change). Where this decision has been made, this is documented in Appendix A of this Schedule. The calculated values, before and after rounding, can be found in Appendix C.

·         HIL setting needs to be done with sufficient transparency to be replicated by other knowledgeable persons. All equations and underlying assumptions adopted in the derivation of each HIL are presented in Appendices A to C of this Schedule.

·         the HIL setting process has identified areas of uncertainty and the effect of these on the final HIL. In addition the setting of the HILs has recognised the level of uncertainty inherent in the derivation of these values and hence the HILs have been rounded to no more than 1 or 2 significant figures.

This Schedule is structured according to the five-step risk assessment process (also refer to Appendices A to D for more specific detail), which is summarised below.

·         Issues identification establishes the scope and purpose for the derivation of the HILs.

·         Data collection and evaluation entails the analysis of information about contaminants of concern and exposure pathways. Data collection for the derivation of the HILs has been carried out by literature review of Australian and international sources, and is considered according to the type of data, as part of discussion of the generic land use scenarios, the toxicity assessment and the exposure assessment.

·         Toxicity assessment identifies the effect of the contaminants of concern on sensitive populations and the most appropriate reference value for the quantitative assessment of dose-response. The approach adopted has been to review and use relevant published peer-reviewed toxicity reference values (i.e. not to undertake a comprehensive toxicity study to derive separate toxicity reference values).

·         Exposure assessment involves the relevance and estimation of the magnitude, frequency, extent and duration of exposures to contaminants under each of the generic land use scenarios. The general exposure assessment process applied in the derivation of the HILs is described in this Schedule, as is the process applied in estimating exposure point concentrations for volatile contaminants.

·         Risk characterisation combines the outcomes of all of the previous stages of the risk assessment into quantitative and qualitative expressions of risk and uses this information to derive risk-based HIL values.

·         Uncertainty and sensitivity analysis is a key part of the risk assessment process and was undertaken during the derivation of the HILs. It identifies the key assumptions and data gaps associated with the derivation of HILs and establishes the exposure parameters that have the greatest implications for the resultant HILs. The uncertainty and sensitivity analyses provide a ‘reality check’ for the HILs and are also described in this Schedule.

The HIL values are the outcomes of this risk assessment process and are presented in Tables 2 and 3 in this Schedule.


 

1.5              Objectives

The scope and purpose for the derivation of the HILs was established during the NEPM review described in Section 1.1. The key objectives are:

·         to produce health-based soil investigation levels suitable for use in Australian contaminated land assessments

·         to produce HILs that are relevant for Australian land uses, environment, climate and population

·         to produce HILs with consistent and transparent derivation, including assumptions

·         to provide HILs for a list of priority contaminants as established by the NEPM review

·         to produce HILs that are based on relevant, up-to-date, reviewed toxicological research

·         to produce HILs using risk assessment methodologies that are consistent with Australian policy and best international practice.

2                  Presentation of the health-based investigation levels

This chapter presents the HILs for soil contaminants. The HILs have been designed to be protective of the health of most people who could potentially be exposed to soil contaminants under four broad land use categories, not including sensitive sub-populations:

·         HIL A – residential with garden/accessible soil

·         HIL B – residential with minimal opportunities for soil access

·         HIL C – public open space/recreational areas

·         HIL D – commercial/industrial premises.

Further details of each of these generic land use scenarios are provided in Section 3 of this Schedule. Note that HIL A is applicable to homes with a garden large enough to provide an area where children could play and/or where vegetables could be grown. A small paved back yard with small flower beds but without a lawn would be included in HIL B.

 

The terms ‘low’, ‘medium’ and ‘high’ density are commonly used in land use zonings in Australia. Low density would normally be equivalent to HIL A and high density to HIL B. The definition of medium density however is not consistent and the relevance of HIL A or HIL B to this land use should be considered on a site-specific basis.

2.1              Stockholm Convention

The Stockholm Convention on POPs is a global convention to protect human health and the environment from chemicals that persist in the environment for long periods, become widely distributed geographically and accumulate in the fatty tissue of humans, domesticated food animals and wildlife. Exposure to POPs can lead to serious health effects including certain cancers, birth defects, dysfunctional immune and reproductive systems, greater susceptibility to disease, and even diminished intelligence.

 

The Stockholm Convention requires its parties to take measures to eliminate or reduce the release of POPs into the environment. This convention was adopted in 2001 and came into force in 2004. Australia ratified the convention in 2004.

 

The POPs included in the Stockholm Convention are covered by three separate annexes:

·         Annex A (requiring elimination of intentional production and use) - includes aldrin, chlordane, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex, toxaphene and polychlorinated biphenyls (PCBs)

·         Annex B (requiring restriction) - includes DDT

·         Annex C (requiring reduction/elimination of unintentional production) - includes polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF), hexachlorobenzene and PCBs.

Under the terms of the Stockholm Convention, a regular review process allows for additional chemicals to be nominated, and after appropriate review, included in the Convention.

 

Chemicals added to the Convention in 2009 included:

·         Annex A - alpha hexachlorocyclohexane, beta hexachlorocyclohexane, chlordecone, hexabromobiphenyl, hexabromodiphenyl ether, heptabromodiphenyl ether, lindane, pentachlorobenzene, tetrabromodiphenyl ether, pentabromodiphenyl ether

·         Annex B - perfluorooctane sulfonic acid, its salts and perflurooctane sulfonyl fluoride.

Further consideration of the data available for these chemicals and the potential for developing an HIL will be included in subsequent reviews of the HILs.

 

HILs have been developed for all POPs adopted in the Stockholm Convention prior to 2009, with the exception of PCDD/PCDF. These chemicals do not have HILs but a contaminated site that has a history suggesting the likely presence of dioxins would require a site-specific health risk assessment (refer Section 12 of Schedule B2).

2.2              Summary of HILs

The HIL values for the four broad land use categories are presented in Table 2. Additional information to assist in the use of the HIL values during a site-specific assessment is presented below.

2.2.1        Laboratory level of reporting

The available laboratory detection limits should be reviewed in conjunction with the HILs to ensure that the most relevant detection limit is employed and the collection of additional site-specific information (for example, soil vapour data) is appropriate.

2.2.2        Polycyclic aromatic hydrocarbons

The assessment of the health risk posed by polycyclic aromatic hydrocarbons (PAHs) is complicated by the large number of individual PAHs and the complex mixtures that exist in the environment. A specific HIL value has only been derived for the carcinogenic PAHs, based on the toxicity of benzo(a)pyrene (BaP). For other carcinogenic PAH compounds or carcinogenic PAH mixtures, the toxicity equivalence factor (TEF) approach is recommended. The TEF approach assumes that the risk posed by individual carcinogenic PAHs is additive and proportional to the potency of each compound in the mixture. The potency of individual carcinogenic PAHs is expressed relative to benzo(a)pyrene.

 

Naphthalene, the most significant volatile PAH, requires separate assessment, as the vapour inhalation pathway is of greater significance. The assessment of potential naphthalene exposures should consider the Health Screening Level (HSL) for naphthalene derived from exposure to petroleum hydrocarbons (Schedule B1).

 

To apply the HIL to a mixture of carcinogenic PAHs, the concentration of each carcinogenic PAH in the mixture should be multiplied by the respective TEF outlined in Table 1 and the resulting values summed for comparison with the benzo(a)pyrene HIL value.

Table 1. Toxicity equivalence factors for PAHs

PAH

TEF

Benzo(a)anthracene

0.1

Benzo(a)pyrene

1

Benzo(b+j)fluoranthene

0.1

Benzo(g,h,i)perylene

0.01

Benzo(k)fluoranthene

0.1

Chrysene

0.01

Dibenz(a,h)anthracene

1

Indeno(1,2,3-cd)pyrene

0.1

Source: CCME (2008)

2.2.3        Toxicity surrogate approach

A number of groups of chemicals addressed in the derivation of the HILs contain a number of similar chemical constituents where there is a mix of information on individual chemicals. In cases where there is insufficient information to derive separate HILs for each individual compound, the toxicity surrogate approach has been applied to the derivation of HILs for these substances. This approach involves the generation of an HIL value for a single ‘indicator’ chemical and the application of this information directly to the assessment of other similar chemicals within the group.

 

HIL values derived using the toxicity surrogate approach include cresols (methylphenols), DDT, aldrin and dieldrin, polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). The sum of all the individual chemical concentrations within each of these groups can be compared directly to the HIL value, based on the assumption that their effects are similar and additive.

2.2.4        Inorganic mercury

The HIL value for inorganic mercury was derived using the physicochemical characteristics of mercuric mercury (Hg2+). This value does not include the potential for the inhalation of vapours derived from elemental mercury. A site-specific assessment should be undertaken if elemental mercury is present or suspected to be present.

2.2.5        PCBs

The HIL value for PCBs relates to non-dioxin-like PCBs only. Where the assessment indicates the potential for a PCB source to be present on the site, the HILs may not be sufficiently protective. Hence a site-specific assessment of exposure to all PCBs, including dioxin-like PCBs should be undertaken.

2.2.6        Interim HILs for volatile organic chlorinated compounds

Investigation levels derived for the volatile organic chlorinated hydrocarbons (VOCCs) are presented as interim HILs, as the methodology adopted in the derivation of these values is not as fully developed as that for the non-volatile HILs. The application and revision of these values will rely on improvements in the understanding of the behaviour of chlorinated solvents in transferring from soil to indoor air.

 

The interim HIL values derived for volatile compounds are driven by the vapour intrusion pathway (that contributes >99% of the total risk where all pathways are considered). However, it is noted that there are limitations and uncertainties associated with the assessment of volatile contaminants on the basis of soil concentrations. As these limitations are significant for volatile organic chlorinated compounds, interim HILs for soil have not been derived. Rather it is recognised that where indoor/ambient air data cannot be collected (or the data is affected by background sources), the most relevant approach to the assessment of this pathway is through the collection of soil vapour data. On this basis, interim HILs have been developed for soil vapour.

 

It is noted that for short-duration exposures such as during intrusive works where direct contact with the source may occur (not addressed in the derivation of HILs) other exposure pathways (in addition to vapour inhalation) may be more significant and require evaluation on a site-specific basis.

 

Interim HILs are relevant to soil vapour that may have been derived from a soil or groundwater source, or a combination of both.

 

The values have been derived assuming a slab-on-ground building is present directly above the contaminant source. Groundwater, if present, is assumed to be deeper than the building foundations (i.e. no contact between the building foundations and groundwater at any time).

 

In circumstances where the building type differs (for example, inclusion of a crawl space or basement), or where there is the potential for preferential vapour pathways to be present, a site-specific assessment should be undertaken.

 

Further information on the assessment of volatile substances, including VOCCs, can be found in Schedule B2.

2.2.7        Free cyanide

Cyanide-impacted soils are often dominated by stable cyanide-metal complexes that are of low inherent toxicity and are non-volatile. No HIL for complexed cyanide is presented because of the low toxicity. Free cyanide (defined as the cyanide ion (CN-) or hydrogen cyanide (HCN)) is only formed in environments that are dominated by weak cyanide-metal complexes (for example, silver cyanide) and dissolved cyanide complexes.

 

The HIL has been derived on the basis of free cyanide and it is recognised that the measurement of free cyanide in soil is difficult. Measurement is difficult due to instability of not only free cyanide but also cyanide metal complexes that can produce free cyanide. A cautious approach (Department of Resources, Energy and Tourism 2008;  ICMI 2009), is to measure free cyanide and other dissociable cyanide species that could produce free cyanide either by dilution or by other natural processes (refer to US EPA method 9016). The US EPA Weak Acid Dissociable Cyanide (WAD) method measures free cyanide plus the cyanide associated with most unstable metal cyanide complexes. The WAD cyanide refers to any species where cyanide is liberated at pH 4.5. Such species include HCN (aq) and CN-, and the majority of Cu, Cd, Ni, Zn and Ag complexes. If the WAD result conforms to the HIL, then the free cyanide level is also in compliance with the HIL.

 

The presence of free cyanide in soil and the potential for formation of HCN is complex and depends on the soil pH, ionic strength and complexation. The ability of standard vapour models to estimate the concentration of HCN in air (indoors and outdoors) is considered to be poor (RIVM 2001) due to the complexity of the processes involved. Hence, the HIL derived for free cyanide does not address issues that may be associated with the formation of HCN gas and potential exposures indoors and outdoors. These exposures need to be addressed on a site-specific basis.

2.2.8        Home-grown produce

Where relevant for each compound assessed, the HIL A values assume that 10% of vegetable and fruit consumption comes from produce grown on the contaminated site. Details on the potential significance of uptake into home-grown fruit and vegetable crops are presented in the chemical summaries in Appendix A.

 

Intakes from other home-grown produce, namely eggs and poultry meat, have not been addressed in the derivation of the HILs. These intakes/exposures may be a significant exposure pathway for some soil contaminants and should be assessed on a case-by-case basis.

Table 2. Health investigation levels for soil contaminants

Chemical

Health-based investigation levels (mg/kg)

Residential1 A

Residential1 B

Recreational1 C

Commercial/
industrial1 D

Metals and Inorganics

Arsenic2

100

500

300

3000

Beryllium

60

90

90

500

Boron

4500

40 000

20 000

300 000

Cadmium

20

150

90

900

Chromium (VI)

100

500

300

3600

Cobalt

100

600

300

4 000

Copper

6000

30 000

17 000

240 000

Lead3

300

1200

600

1500

Manganese

3800

14 000

19 000

60 000

Mercury (inorganic)5

40

120

80

730

Methyl mercury4

10

30

13

180

Nickel

400

1200

1200

6000

Selenium

200

1400

700

10 000

Zinc

7400

60 000

30 000

400 000

Cyanide (free)

250

300

240

1500

Polycyclic Aromatic Hydrocarbons (PAHs)

Carcinogenic PAHs

(as BaP TEQ)6

3

4

3

40

Total PAHs7

300

400

300

4000

Phenols

Phenol

3000

45 000

40 000

240 000

Pentachlorophenol

100

130

120

660

Cresols

400

4700

4 000

25 000

Organochlorine Pesticides

DDT+DDE+DDD

240

600

400

3600

Aldrin and dieldrin

6

10

10

45

Chlordane

50

90

70

530

Endosulfan

270

400

340

2000

Endrin

10

20

20

100

Heptachlor

6

10

10

50

HCB

10

15

10

80

Methoxychlor

300

500

400

2500

Mirex

10

20

20

100

Toxaphene

20

30

30

160

Herbicides

2,4,5-T

600

900

800

5000

2,4-D

900

1600

1300

9000

MCPA

600

900

800

5000

MCPB

600

900

800

5000

Mecoprop

600

900

800

5000

Picloram

4500

6600

5700

35 000

Other Pesticides

Atrazine

320

470

400

2500

Chlorpyrifos

160

340

250

2000

Bifenthrin

600

840

730

4500

Other Organics

PCBs8

1

1

1

7

PBDE Flame Retardants (Br1-Br9)

1

2

2

10

Notes:

(1)     Generic land uses are described in detail in Section 3.

HIL A: Residential with garden/accessible soil (home-grown produce <10% fruit and vegetable intake (no poultry)), also includes childcare centres, preschools and primary schools

HIL B: Residential with minimal opportunities for soil access; includes dwellings with fully and permanently paved yard space such as high-rise buildings and apartments

HIL C: Public open space such as parks, playgrounds, playing fields (e.g. ovals), secondary schools and footpaths. This does not include areas of undeveloped open space where the potential for exposure is lower and where a site-specific assessment may be more appropriate.

HIL D: Commercial/industrial includes premises such as shops, offices, factories and industrial sites.

(2)     Arsenic: HIL for arsenic assumes 70% oral bioavailability. Site-specific bioavailability may be important and should be considered where appropriate (refer Schedule B7).

(3)     Lead: HIL for lead is based on blood lead models (IEUBK for HILs A, B and C and adult lead model for HIL D) where 50% oral bioavailability has been considered. Site-specific bioavailability may be important and should be considered where appropriate.

(4)     Methyl mercury: assessment of methyl mercury should only occur where there is evidence of its potential source. It may be associated with inorganic mercury and anaerobic microorganism activity in aquatic environments. In addition, the reliability and quality of sampling/analysis should be considered.

(5)     Elemental mercury: HIL does not address elemental mercury. A site-specific assessment should be considered if elemental mercury is present, or suspected to be present.

(6)     Carcinogenic PAHs: HIL for carcinogenic PAHs is based on the 8 carcinogenic PAHs and their respective TEFs (potency relative to BaP) adopted by CCME 2008. The BaP TEQ is calculated by multiplying the concentration of each carcinogenic PAH in the sample by its BaP TEF, given below, and summing these products.

 

PAH species

TEF

PAH species

TEF

Benzo(a)anthracene

0.1

Benzo(g,h,i)perylene

0.01

Benzo(a)pyrene

1

Chrysene

0.01

Benzo(b+j)fluoranthene

0.1

Dibenz(a,h)anthracene

1

Benzo(k)fluoranthene

0.1

Indeno(1,2,3-c,d)pyrene

0.1

 

Where the BaP occurs in bitumen fragments it is relatively immobile and does not represent a significant health risk.

(7)     Total PAHs: HIL for total PAH is based on the sum of the 16 PAHs most commonly reported for contaminated sites (WHO 1998). The application of the total PAH HIL should consider the presence of carcinogenic PAHs and naphthalene (the most volatile PAH). Carcinogenic PAHs reported in the total PAHs should meet the BaP TEQ HIL. Naphthalene reported in the total PAHs should meet the relevant HSL.

(8)     PCBs: HIL for PCBs relates to non-dioxin-like PCBs only. Where a PCB source is known, or suspected, to be present at a site a site-specific assessment of exposure to all PCBs (including dioxin-like PCBs) should be undertaken.

 

Table 3. Interim soil vapour health investigation levels for volatile organic chlorinated compounds

Chemical

Interim soil vapour HIL (mg/m3)

Residential1 A

Residential1 B

Recreational1 C

Commercial/ Industrial1 D

TCE

0.02

0.02

0.4

0.08

1,1,1-TCA

60

60

1200

230

PCE

2

2

40

8

cis-1,2-dichloroethene

0.08

0.08

2

0.3

Vinyl chloride

0.03

0.03

0.5

0.1

Notes:

(1)     Land use settings are equivalent to those described in Table 2 Footnote 1 and Section 3 of this Schedule, except for secondary school buildings which should be assessed against residential ‘A/B” for vapour intrusion purposes.

(2)     Interim HILs for VOCCs are conservative soil vapour concentrations that can be adopted for the purpose of screening sites where further investigation is required on a site-specific basis. They are based on the potential for vapour intrusion indoors using an indoor air-to-soil vapour attenuation factor of 0.1 (for interim HIL A, B and D) and an outdoor air attenuation factor of 0.05 (interim HIL C).

(3)     Application of the interim HILs is based on a measurement of shallow (to 1 m depth) soil vapour (or deeper where the values are to be applied to a future building with a basement) or sub-slab soil vapour.

(4)     The applicability of the interim HILs needs to be further considered when used for other building types such as homes with a crawl-space and no slab which require site-specific assessment.

(5)     Use of the interim HILs requires comparison with data that has been collected using appropriate methods and meets appropriate data quality requirements.

(6)     Oral and dermal exposure should be considered on a site-specific basis where direct contact exposure is likely to occur.

3                  Generic land use scenarios

3.1              Introduction

Assessments of potential risks to human health resulting from site contamination are based on CSMs that identify the conditions through which exposure to contaminants can occur. The key components of a CSM are the contaminant source, receptors (human populations) and exposure pathways. For further information on developing CSMs refer to Schedule B2.

 

The source addressed in this Schedule is a soil source and this is the source represented in all CSMs presented. The HILs are not derived for the purpose of assessing groundwater sources. However the interim soil vapour HILs for VOCCs may be applied to soil vapour derived from a soil or groundwater source, or a combination of both for these compounds.

 

Four generic land use scenarios have been used to derive the HILs. These are based on the typical settings in Australia under which people may be exposed to contaminated soil. A separate set of HILs has been developed for each generic land use category, because the sensitive populations and intensity, frequency and means of exposure to soil contaminants can differ according to land use.

 

The four generic land use scenarios used in the derivation of the HILs are described below. Also in this Schedule is a description of the environment and buildings considered under each land use scenario, a description of the characteristics of relevant human populations, and relevant exposure pathways applied under each land use scenario. This information is designed to allow risk assessors to gauge the applicability of the HILs to the circumstances at individual sites. The assessment of soil contamination at sites that are not adequately represented by any of the standard land use scenarios is also discussed in this Schedule.

 

The generic land use scenarios considered in the development of the HILs are:

·         HIL A - Residential scenario with garden/accessible soil (home-grown produce <10% fruit and vegetable intake and no poultry; includes childcare centres, preschools, primary schools

·         HIL B - Residential with minimal opportunities for soil access; includes dwellings with fully and permanently paved yard space such as units, high-rise buildings and apartments

·         HIL C - Public open space scenario, including parks and playgrounds, playing fields (e.g. ovals), secondary schools and footpaths

·         HIL D - Commercial/industrial scenario, including shops, offices, factories and industrial sites.

The HILs have been derived for the above land use scenarios based on long-term exposures for the most sensitive receptor populations exposed. The HILs are therefore considered to be protective of exposures to other receptor populations; however, the HILs do not specifically address short-duration exposures that may occur during construction and maintenance of a site (including intrusive works). These exposures should be addressed on a site-specific basis.

 

These land use scenarios are broadly consistent with exposure settings A, D, E and F respectively, as described in NEPC (1999). When land is used for more than one purpose, the HILs that are relevant to the more sensitive land use should be adopted for that site.

 

3.2              Description of the generic land use scenarios

3.2.1        HIL A values – residential land use scenario with garden/accessible soil

Residential land use includes a variety of building densities, ranging from separate low-density dwellings to high-density unit blocks. The residential land use scenario considered in the derivation of the HIL A values is low-density residential, including a sizeable garden (referring to the presence of sufficiently large areas of soil in a garden that may be accessible on a daily basis by young children and adults).

 

The HIL A values are also applicable to the preliminary assessment of potential risks at sites where children are likely to be the most sensitive human receptors, including childcare centres, kindergartens, preschools and primary schools and their integral playgrounds. The scenario is designed to represent a typical residential land use. The HIL A values will also be protective of circumstances where less exposure to soil would be likely (for example, older people, or without fruit and vegetable gardens).

 

It is noted that for people within sensitive sub-populations; for example, the immunosuppressed, those with pre-existing illness, or those with pica behaviour, the HILs may not be sufficiently protective of health and site-specific risk assessment (or criteria) or management strategies may be required.

 

This land use scenario assumes typical residential properties, consisting of single storey dwellings supported by ground-level slabs or multistorey dwellings where living areas are on the ground floor and there is accessible soil in the front and backyard areas.

 

These residences may have private gardens, consisting of lawns, garden beds and small vegetable gardens and areas of fruit trees, but no poultry. The occupants of the dwellings include adults, children and infants, who spend the majority of their time on the residential properties and use the outdoor areas of the residences on a frequent basis, for activities such as gardening or recreation. The CSM for this land use scenario is provided in Figure 1.

 

The derivation of soil HILs addresses all non-volatile compounds and exposure pathways. The interim soil vapour HILs for VOCCs address the vapour pathway, only for these compounds.

 

Figure 1. CSM for HIL A - standard residential land use scenario with garden/accessible soil

3.2.2        HIL B values - residential scenario with minimal opportunities for soil access

The residential land use scenario considered for the HIL B values is high-density residential, not including a private garden. This land use scenario assumes typical residential unit blocks, consisting of multistorey buildings where living areas are on the ground floor (constructed on a ground level slab or above subsurface structures including basement car parks or storage areas).

 

Occupants of the buildings considered in the development of the HIL B values have access to yard spaces that are largely covered by permanent paving, with some small areas of landscaping or lawns. Opportunities for direct access to soil by residents of these buildings are therefore minimal but there may be some potential for residents to inhale, ingest or come into direct dermal contact with dust (particulates) derived from the soil on the site. Landscaped/playground (including sandpit) areas used for recreation within a high-density development should be assessed on the basis of the more conservative HIL C values.

 

The occupants of the dwellings are adults, children and infants who spend the majority of their time indoors within the residential properties, with some limited use of communal outdoor areas on site. The residents that are considered to be most susceptible to health risks associated with soil contaminants are the residents of ground floor units, due to the greatest potential for outdoor soil to be tracked indoors and vapour intrusion occurring with residences immediately overlying contaminated soil. The CSM for this land use scenario is provided in Figure 2.

Figure 2. CSM for HIL B - residential land use scenario with minimal opportunities for soil access

 

It is noted that the derivation of soil HILs addresses all non-volatile compounds and exposure pathways. The interim soil vapour HILs for VOCCs address the vapour pathway only for these compounds.

3.2.3        HIL C values - public open space scenario

Public open space land use includes a variety of exposure scenarios such as parks and playgrounds (including sandpits), recreational areas and playing fields that are fully accessible to the public and where the public may potentially spend a significant amount of time.

 

This land use scenario assumes that the open space areas are in areas where young children may have supervised access and use the area outside of the home environment for frequent short periods of time (up to 2 hours a day, 7 days a week). Other users may include older children and adults who may visit the area frequently for a range of recreational purposes. These open space areas may contain lawns, gardens, vegetated areas and walkways, with some limited areas of hardstand and some areas of exposed soil. The open space areas may contain buildings such as amenity blocks, but individuals who visit these areas are considered to spend the majority of their time outdoors where the exposure is limited to outdoor soil.

 

The CSM for this land use scenario is provided in Figure 3. In addition, the derivation of soil HILs addresses all non-volatile compounds and exposure pathways. The interim soil vapour HILs for VOCCs addresses the vapour pathway only for these compounds.

 

Scenario HIL C does not directly apply to non-recreational open spaces, such as road reserves, where the potential for exposure (and frequency of exposure) is lower and which should be subject to a site-specific assessment (where appropriate).

 

Figure 3. CSM for HIL C - public open space land use scenario

3.2.4        HIL D values - commercial/ industrial scenario

The land use scenario considered for the HIL D values is commercial/industrial, which assumes typical commercial or light industrial properties, consisting of single or multistorey buildings where work areas are on the ground floor (constructed on a ground level slab) or above subsurface structures (such as basement car parks or storage areas).

 

The land use scenario does not include more sensitive uses that may be permitted under relevant commercial or industrial zonings. These more sensitive uses include childcare, educational facilities, caretaker residences and hotels and hostels, etc. Information on uses permitted under local council zoning schemes for commercial/industrial land use can be obtained from local council planning zones/schemes. Should these more sensitive uses be permitted, then HIL A or HIL B values should be considered.

 

The dominant users of commercial/industrial sites are adult employees, who are largely involved in office-based or light indoor industrial activities. The employees who are most susceptible to health risks associated with volatile soil contaminants are the employees who work in offices on the ground floor, as the greatest potential for vapour intrusion occurs with workspaces immediately overlying contaminated soil.

 

The outdoor areas of the commercial/industrial facilities are largely covered by hardstand, with some limited areas of landscaping or lawns and facilities. Employees may make use of outdoor areas of a commercial/industrial premises for activities such as meal breaks. Opportunities for direct access to soil by employees using these facilities are likely to be minimal, but there may be potential for employees to inhale, ingest or come into direct dermal contact with dust particulates derived from the soil on the site. The CSM for this land use scenario is provided in Figure 4.

 

Figure 4. CSM for HIL D - commercial/industrial land use scenario

 

The derivation of soil HILs addresses all non-volatile compounds and exposure pathways. The interim soil vapour HILs for VOCCs address the vapour pathway only for these compounds.

3.2.5        Sensitive populations

3.2.5.1       Overview

The HILs for each land use scenario have been developed to be protective of the majority of human populations that are sensitive to potential health risks from soil contamination. The HILs depend upon both the exposure scenario and the toxicity reference values selected for the contaminant.

 

The level of exposure of a given human population to health risks within a particular land use scenario is related to physiological factors (for example, children are often more heavily exposed to contaminants than adults because, in comparison to their body weight, they have higher rates of inhalation and ingestion and a larger skin surface area) and the frequency, extent and duration of exposure (for example, permanent residents are a more sensitive population than intermittent visitors).

 

The toxicity reference values were selected from collated peer-reviewed sources using the data sources described in Schedule B4.

 

Unless otherwise noted, all of these sources provide criteria that represent tolerable levels of exposure to the population inclusive of those individuals considered to be sensitive to the contaminant concerned. The toxicity criteria therefore inherently incorporate protection to sensitive populations. Different sources of toxicity criteria provide slightly differing approaches to protection of sensitive populations because they are derived by different bodies (for example, NHMRC, WHO and US EPA), which may have differing policy positions. The source and basis of selected toxicity reference values are presented on a compound-specific basis in Appendix A.

3.2.5.2       Residential and open space land use scenarios (HIL A, B and C)

The populations that are usually most sensitive to health risks associated with soil contamination in both low-density and high-density residential settings and in the open space scenario are young children aged 2-3 years. The characteristics of exposed populations applied in the development of the HILs have been derived in accordance with the recommendations outlined by enHealth (2012a). Young child residents and recreational users, while assessed on the basis of parameters relevant to 2-3 year old children, have been taken to be representative of children aged between 0 and 6 years of age who live within the same dwelling or visit the same open space area for their entire childhood.

3.2.5.3       Commercial/industrial land use scenario (HIL D)

Adults of working age are the population usually most sensitive to health risks associated with soil contamination within the generic commercial/industrial land use scenario. Although many commercial premises welcome children on an intermittent basis, it is unlikely that children visit the majority of workplaces frequently. Similarly, in commercial premises where children are regular visitors, such as shopping centres, both the duration and frequency of child exposures are generally lower than that of a full-time adult employee.

 

In accordance with the recommendations outlined in enHealth (2004), the adult employees addressed in the HIL D values have been considered to work within the same commercial/industrial premises for their full working life (30 years). The HILs developed for the commercial/industrial land use scenario are not applicable to a site used frequently by more sensitive groups such as children (within childcare centres, hospitals and hotels) and the elderly (within hospitals, aged care facilities and hospices).

3.3              Exposure pathways

For each land use, consideration has been given to the ways in which people could be exposed to soil contamination. The term ‘exposure pathway’ is used to describe the course that a contaminant takes from its source area to reach an exposed population. An exposure pathway is considered to be complete when a receptor (for example, resident or worker) receives a dose of the contaminant.

 

For the purposes of developing the HILs, it has been assumed that exposure could potentially occur via the following exposure pathways:

·         incidental ingestion of surface soil and indoor dust

·         indoor and outdoor inhalation of dust

·         consumption of home-grown produce (including vegetables and fruit, but excluding poultry meat and eggs)

·         consumption of soil adhering to home-grown produce

·         dermal contact with surface soil and dust particulates

·         indoor and outdoor inhalation of vapours derived from soil.

Not all exposure pathways are relevant to all land use categories. For example, in the open space scenario, it is assumed that there are no permanently occupied buildings in which indoor air could be impacted by vapours derived from the underlying soil. Hence, exposure to soil contaminants within open space areas occurs largely in the outdoor environment and the exposure pathway of indoor vapour inhalation is not applicable. Similarly, the consumption of home-grown produce and soil adhering to home-grown produce is only applicable to the low-density residential land use scenario.

 

The exposure pathways considered in the development of HILs for each of the four different land use categories are summarised in Table 4.

 

Table 4. Exposure pathways considered for the four generic land use categories

Exposure pathways