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The DSS software is produced by the American Petroleum Institute (API), and is used to estimate human exposure, carcinogenic risk, and non-carcinogenic effects from underground and above ground releases of petroleum products.

API's Risk and Exposure Assessment Decision Support System (DSS), Version 2.0, calculates carcinogenic risks to, and non-carcinogenic effects on, human receptors along six exposure pathways: 

  • ingestion of water
  • dermal absorption while bathing
  • inhalation while showering
  • inhalation of soil emissions
  • dermal contact with soil
  • soil ingestion

Risk assessments can be conducted for numerous petroleum hydrocarbons, petroleum product additives, chlorinated hydrocarbons, and metals.

As with Version 1.0, Version 2.0 of the DSS incorporates a number of fate and transport models for easy calculation of receptor point concentrations. Exposure, carcinogenic risk, and non-carcinogenic effects (hazard indices) are calculated using procedures consistent with those described in EPA guidance. DSS input data is via KnowledgePro for Windows, with output files from the DSS in EXCEL. Built-in EXCEL macros permit easy viewing and printing of risk assessment results in a number of convenient and illustrative formats.

New features incorporated into Version 2.0 of the DSS are designed to make the software easier to use, and to increase the modelling options available to the user. These new features include: 

  • New API VADSAT vadose zone/saturated zone contaminant fate and transport model
  • Upgraded SESOIL vadose zone model (allows modelling of additional soil layers)
  • Upgraded AT123D saturated zone model (allows user adjustment of time steps)
  • Improved AT123D source zone coordinate system
  • New module allows importation of concentration/time series data from external model runs

The database in Version 2.0 provides physical/chemical and toxicological property data for 86 petroleum hydrocarbons, petroleum product additives, chlorinated hydrocarbons, and metals. It can also be modified by the user..

The API-DSS software requires Microsoft EXCEL version 5.0 for Windows.

Details of API-DSS


AQUARISK utilises the ANZECC Water Quality Guidelines, and is able to take field information, such as water quality measurements and toxicity data, and predict the likelihood of an adverse biological impact. With this information, the user is able to quantify the improvement needed in water quality to prevent any adverse effect on the ecosystem.

The model can be used to assess whether the predicted concentrations in surface water will pose an environmental risk. Therefore it could be very useful as a supplementary assessment tool (e.g. in combination with RISK4 or RBCA or another fate and transport model). AQUARISK can accurately predict the risk posed by contamination on individual species of aquatic life. The risks identified are reported in terms that address the relevant regulatory criteria. AQUARISK then evaluates the reduction needed to meet agreed targets.

The software was developed by the Australian Nuclear Science and Technology Organisation (ANSTO) and has been designed to work on a standard desk-top computer and can be modified easily to meet the requirements of the user. While the code was created to assess the effect of metals in water, it can also be used to predict the effect of most pollutants in any environment. This makes it ideal as a way to ascertain the impact on fresh water environments of urban development, village expansion in developing countries and landfill sites near watercourses.

AQUARISK is easy to use and has the versatility to be applicable wherever fresh water ecosystems are under threat. 

Refer to: http://ats.business.gov.au/aws/NSW_343/


CalTOX is a Multimedia Total Exposure Model for Hazardous Waste Sites developed by the California Department of Toxic Substances Control, Human and Ecological Risk Division.

It is Excel spreadsheet-based software that aids in assessing risk posed by some hazardous materials in the environment. A multimedia exposure assessment tool simulates leaching of contaminants from a waste disposal facility or contaminated site.

CalTOX predicts the concentrations of a contaminant at a given receptor and its principle application is for assessing human health risks. Its application to ecological risk assessment is somewhat limited.

The model incorporates a comprehensive database covering physical characteristics, and fate and transport data. Additional parameters can be added to databases, if required. BTEX and metals already included in the database.

The site characteristics database is limited at present, although further site data can be readily added. These site scenarios could be incorporated as New Zealand region-specific physical data, including soils data).

The principal limitation with the models is that terrestrial fauna are not included, and onsite terrestrial flora are modelled to calculate contaminant concentrations for human ingestion.

Details of CalTOX


EcoFATE is an ecosystems-based environmental and ecological risk assessment model for chemical emissions from point and non-point sources in freshwater and marine aquatic ecosystems, including lakes, rivers and marine inlets.

EcoFATE is used to assess the cumulative impact of chemical inputs in terms of contaminant concentrations in water, sediment and biota of an entire ecosystem. It interprets these concentrations in terms of exceedance of environmental criteria and standards, potential for toxic effects in biota of the ecosystem and risks to human beings exposed to contaminated fish products or contaminated water

EcoFATE comprises a combination of an environmental fate, food-web bioaccumulation, toxicological hazard, and human health risk assessment models, that are integrated to directly relate chemical emissions to concentrations, toxic effects and human health risks. Each of the models is based on best available knowledge of the mechanisms of chemical distribution, toxicity and risk. The assessments can be done on a time-dependent and time-independent (ie. steady-state) basis.

The model is very easy to use and flexible and has the potential to be used in conjunction with risk assessment models focussing on onsite effects. The principal limitations with the EcoFATE model are the large amount of data required, and a thorough understanding of the complexities of fate and transport of contaminants in the aquatic environment is required to adequately use the model.

Details of EcoFATE


The USEPA has developed software that calculates for selected chemicals and can print out a table of ETs and their sources.

ETs are media-specific benchmark values for those chemicals commonly found in surface water, sediment and soil samples at sites (values for soil are still being developed), and defined as media-specific contaminant concentrations above which there is sufficient concern regarding adverse ecological effects to warrant further site investigation". Therefore ETs may be useful in the NZ setting for identifying contaminants that may pose a threat to ecological receptors and focus further site activities on those contaminants and the media in which they are found. However, for those chemicals with the potential to bioaccumulate to toxic levels in upper trophic wildlife (e.g., methyl mercury, PCBs, DDT, dioxins, and lead), these benchmarks may not be low enough at some sites.

Refer to: http://www.epa.gov/oerrpage/superfund/resources/ecotox/#et


RAIS (Risk Assessment Information System) contains risk assessment tools that include risk-based preliminary remediation goal calculations, a toxicity database, risk calculations, and ecological benchmarks. The Tools are designed for use at all USDOE sites and can be customized for site-specific conditions. A key feature of this model is that the comprehensive set of ecotoxicological screening benchmarks for surface water, sediment, and surface soil is included in the model as a searchable database.

Refer to: http://risk.lsd.ornl.gov/homepage/rap_tool.shtml

RAMAS Ecotoxicology

RAMAS Ecotoxicology is used to help undertake population-level ecological risk assessments for environmental contaminants. It carries out ecological risk assessments for two broad systems

  • structured single populations
  • food chains

The model is used to manage variability and uncertainty, express results as ecological risks. In each case, a model of population dynamics and toxicant kinetics is constructed using a Windows interface, and linked to bioassay data. Parameters can be specified as scalars, intervals or distributions, to take account of environmental variability and ignorance.

Monte Carlo simulations are then used to predict future population trajectories, and calculate the risk of adverse events such as extinctions or algal blooms.

Details of RAMAS

Refer to: http://www.ramas.com/

RBCA (Risk Based Corrective Action)

The RBCA Tool Kit for Chemical Releases is a comprehensive modelling and risk assessment and characterisation software package for Tier 1 and Tier 2 assessments. This model was designed to meet the requirements of the ASTM PS 104 98 Standard Guide for Risk-Based Corrective Action, developed in the United States.

RBCA can combine contaminant transport models and risk assessment tools to calculate baseline risk levels and derive risk-based cleanup standards for a full array of soil, groundwater, surface water and air exposure pathways and has been further expanded to allow for automatic calibration with available site data.
The key strength of RBCA is that it can undertake aquatic ecosystem risk assessment by modelling fate and transport of contaminants to, and within the water column. These values can then be compared with database benchmark values, or to user specified water quality criteria.
The principal drawback with RBCA is that in spite of its wide acceptance in North America for human health risk assessment, the model is not widely used in New Zealand, and many regulatory agencies in NZ would not be familiar with this model.

The Risk Based Corrective Action (RBCA) process assesses subsurface contamination associated 

Details of RBCA

Refer to: http://www.gsi-net.com/


RIP is a PC-based software program developed by Golder Associates. It probabilistically simulates the release, transport, and fate of contaminants within engineered and/or natural environmental systems.

Although originally developed to simulate the long-term performance of radioactive waste disposal facilities, the software can be readily applied to more commonly encountered environmental problems, such as contaminant release from landfills and/or hazardous waste sites, and contaminant fate and transport in wetlands, lakes and other complex ecosystems. The software can also be used to simulate complex fate and transport processes within biological systems (e.g., physiologically-based pharmacokinetic modelling).

The transport pathways used in the model can consist of multiple transport and storage media (e.g., groundwater, surface water, air, soil), and both advective and diffusive transport mechanisms can be directly simulated. Transport processes incorporate solubility constraints and partitioning of contaminants between the media present in the system, and can include the effects of complex chemical reactions and decay processes.

It can also model biological transport of contaminants, and like physical transport pathways, is can include any number of transport and storage media (e.g., blood, tissue) which can be linked by a variety of transport mechanisms.

The output produced by RIP consists of predicted contaminant release rates from defined sources and transport pathways, and predicted concentrations within environmental media throughout the system (e.g., groundwater, soil, air, blood). If desired, concentrations in environmental media can be converted to doses and/or health risks by assigning appropriate conversion factors.

An important requirement for using the RIP is that the user has a clear understanding of the features, processes, and events controlling the behaviour of the system to be modelled. The modeller must have a good understanding of the fundamentals of contaminant transport modelling. The RIP model can be run in a deterministic manner, or can represent uncertainty through the use of probability distributions. However the user must have at least a basic understanding of the representation and propagation of uncertainty as a probability distribution.

Refer to: http://www.golder.com/rip/default.htm


The RISC4 model is now relatively widely used in New Zealand and can be used for both human health and ecological risk assessments. RISC4 provides a Tier 1 assessment tool that includes ANZECC 2000 water and sediment quality criteria, and can undertake Tier 2 fate and transport modelling, and Tier 3 risk assessments.

At a Tier 2 level the model can simulate:
Contaminants percolating to groundwater, including groundwater dispersion;
Groundwater contaminants entering surface, including a surface water-sediment pathway and surface water mixing;
Air emissions as dust and or vapour;
Uptake by plants and plant ingestion; and
Human versus ecological risks.

Software operation and data input is straightforward but the interpretation of the output of the model requires an experienced practitioner.

RISC4 model was designed to comply with the ASTM standard (PS104 - 98) Standard Guide for Risk-Based Corrective Action, developed in the United States.

Future versions of RISC are proposed to include food chain modelling for aquatic and terrestrial food webs.

Details of RISC


The Spatial Analysis and Decision Assistance (SADA) is public domain software that incorporates integrated modules to undertake visualization, geospatial analysis, statistical analysis, human health risk assessment, ecological risk assessment, cost/benefit analysis, sampling design, and decision analysis. These modules can be used separately or together to address site-specific concerns when characterizing a contaminated site, assessing risk, determining the location of future samples, and designing remedial measures

The SADA system is very useful for undertaking human health and terrestrial ecological risk assessments, albeit using an extensive US database. However, NZ specific environmental criteria can be used in the model.

The currently available version of SADA is Version 3.0 that includes terrestrial exposure models. Additional modelling capability is planned that will allow for:

Aquatic exposure assessments;
Assessing contaminant mixtures (such as total PAH) on ecological receptors;
Inclusion of toxicity testing of water and sediment using invertebrates and fish; and
The calculation and assessment of toxicity equivalency factors (TEFs) for Dioxins, PCBs and other dioxin-like compounds on ecological receptors.

Details of SADA

Refer to: http://www.tiem.utk.edu/~sada/ (includes a fully functional freeware version)


SimpleBOX is developed by the National Institute of Public Health and the Environment (RIVM). It is a nested multi-media model that determines contaminant concentrations through the following compartments:

  • Air
  • Two water compartments
  • Sediment
  • Three soil compartments
  • Two vegetation compartments.

It uses contaminant concentrations as input and computes both steady state and time-dependent (transient) concentrations as outputs.

As for the CalTOX model, the principal limitation with the SimpleBOX model is that terrestrial and aquatic fauna are not incorporated into the model. However contaminant concentrations in water bodies and sediments can be evaluated against ecological benchmark criteria providing a limited ERA capability if required.

Details of SimpleBOX


It should be noted that a wide range of models are readily available and in wide use in New Zealand (many are public domain) to predict point of exposure (POE) concentrations that may then be evaluated against appropriate NZ criteria. The following models are examples of those in common usage in NZ. For benchmark or screening assessments, predicted concentrations at the selected POE can be compared to ANZECC (2001) or the extensive range of values presented in the RAIS database.


These are in common usage - they can calculate POE the natural attenuation of hydrocarbon and chlorinated compounds - these can be compared to for example aquatic guidelines, after allowing for dilution.

RISKPRO (General Sciences Corporation, 1996)

The RISKPRO exposure assessment system incorporates the same models used by USEPA to evaluate a toxic chemical's behaviour when released to the soil, surface and ground water.

The RISKPRO software package also includes several data bases required to run the models that contain information on toxic chemicals, climate, soil, and population distribution. The RISKPRO system is composed of user interface that controls the simulation codes. The simulation codes include programs for: estimating chemical data; vertical transport of chemicals through the unsaturated zone (SESOIL); solute transport in groundwater (AT123D); predicting the fate of organic chemicals in surface water (EXAMS-II); and multi-media partitioning of chemicals (ENPART).


Biodegradation, flow and transport in the saturated and unsaturated zones in two or three dimensions in heterogeneous, anisotropic porous media or fractured rock. Allows real world modelling of convection, dispersion, diffusion, adsorption, desorption, and microbial processes based on oxygenated, anaerobic first-order decay. The model is ideally suited to very complicated conditions, including heterogeneous geological conditions etc. The model predicts spatial distribution of concentration with time, mass dissolved in water vs. time, mass remaining in NAPL phase vs. time, and mass adsorbed on the solid phase vs. time.


Models such as MINTEQA2 may also be useful to determine speciation and bioavalilabity in aquatic environments. The model can be used to calculate the equilibrium composition of dilute aqueous solutions in the laboratory or in natural aqueous systems. The model is useful for calculating the equilibrium mass distribution among dissolved species, adsorbed species, and multiple solid phases under a variety of conditions including a gas phase with constant partial pressures. A comprehensive database is included that can solve a broad range of problems without need for additional user-supplied equilibrium constants.


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