Lecture 7: Environmental Quality Guidelines

Two types of chemical management

• Management of importation and manufacture of chemicals

• Management of the harmful effects associated with chemical use

Organisations that manage the importation and manufacturing of chemicals

• Australian Pesticides and Veterinary Medicines Administration (APVMA)

• Australian Industrial Chemicals Introduction Scheme (AICIS) (Formerly the National Industrial Chemical Notification and Assessment Scheme (NICNAS)) regulation of importation
  and manufacture of industrial chemicals

• Therapeutic Goods Administration (TGA) – for human medicines

Managing the harmful effects of chemicals

This is done by deriving and using environmental quality guidelines:

• Water Quality Guidelines – Surface water and Groundwater

• Sediment Quality Guidelines

• Soil Quality Guidelines

• Biosolids contaminant guidelines

• Draft mineral fertiliser contaminant guidelines

• Food Safety Standards

• Air toxics limits

• National Assessment Guidelines for Dredging

How do we manage water quality in Australia?

• Australian and New Zealand Guidelines for Fresh and Marine Water Quality (WQGs)

  • WQGs aim to protect water resources for various *Community Values

  • risk-based protection (e.g. % of species) is provided by meeting *Default Guideline Values (DGVs)

*uses previously referred to as Environmental Values

*previously called Trigger Values (TVs)

Community Values protected by Australian Gov

• Aquatic ecosystems

• Primary industries

  • irrigation

  • farm supply

  • livestock

  • farm use

  • aquaculture

  • human consumption of aquatic foods

• Recreation and aesthetics

  • primary contact

  • secondary contact

  • visual amenity

• Drinking water

• Cultural, spiritual and ceremonial

Water quality management framework

• Many essential industries are licensed to pollute (in QLD it is called an Environmental Authority):

  • waste water treatment plants

  • mine and refineries

  • aquaculture and meat processing

• The WQGs are for ambient water and are not meant to be applied directly to discharges emanating from licensed activities

  • underlying philosophies: should not pollute up to guideline, continual improvement

Analogy of EQG policy

When the concentration is < EQG, you CAN NOT increase the pollutant concentration up to the EQG.

When the concentration is > EQG, you are required to decrease the pollutant concentration down to < EQG (may not be given license to operate if your pollution will exceed this level)

Three methods of deriving EQGs

• Background (reference) concentration method

  • used for physicochemical properties and naturally occurring pollutants

• *Worst known case method

• *Risk-based method

  • *used for synthetic pollutants

*decreasing order of this list is preferred method for toxicants

Background (reference) concentration method

• Not used for synthetic chemicals as these do not occur naturally

• Used for physicochemical properties and naturally occurring chemical

• For stressors that cause problems:

  • at high concentrations the guideline is the 80th percentile of the reference distribution

    • e.g. nutrients, suspended particulates, biochemical oxygen demand and salinity

  • at low concentrations the guideline is the 20th percentile of the reference distribution

    • e.g. low temperature, low dissolved oxygen content

  • at high and low concentrations, the guideline is both the 20th and 80th percentile of the reference distribution

    • e.g. temperature, salinity and pH

Percentiles

Each WQG has three values: 20th, 50th and 80th percentiles (%ile) e.g. 20th %ile means that 20% of the data have lower values and 80% have larger values.

How do you apply percentiles to the guidelines?

If your median is between the 20th and 80th percentiles, then you are within the guidelines. A further investigation will occur when the median concentration of n independent samples taken at a test site exceeds the 80pth percentile. For groundwater and HEV waters there should be no detectable changes to the 20th, 50th and 80pth percentiles.

Pros and cons of background concentration method

• Pros

  • a simple concept

• Cons

  • not simple to determine the background concentration when human activity has occurred nearby

  • background concentration varies spatially

  • does not permit any addition of a chemical (overly conservative)

  • not risk based

  • lead to potentially unnecessary investigations

Worst known case method (AF method)

It is the Assessment Factor method which is applied to anthropogenic contaminants:

1. Conduct a thorough literature review for appropriate data

2. Take the lowest toxicity value and divide by an appropriate assessment factor

The AFS are used to account for uncertainty associated with available data:

• Greater certainty that the EQGs will the protect the environment the smaller the AF

• Less certainty the larger the AF

Determining the size of AFs to be used

The AFs for the extrapolations are multiplied together e.g. if there is only acute lab data but for ‘many’ species, the AF would be 100 (10 × 10), if there is only acute lab data for ‘few’ species the AF would be 1000 (10 × 10 × 10).

If you were to calculate a guideline value using the Assessment Factor method what data would you like to have?

• Data for many species

  • because the sensitivity of species varies and the more species there are data for the more likely we will protect most species

• Chronic toxicity data

  • because guidelines should protect organisms from life-time exposure

• Field-based toxicity data

  • because that is more realistic that from controlled laboratory conditions

Pros and cons of AF methods

• Pros

  • very easy to understand

  • very easy to calculate

  • size of AF can be easily adapted

• Cons

  • AFs are arbitrary (little scientific basis)

  • not fully consistent with risk paradigm

  • do not provide a consistent or known level of protection

Species Sensitivity Distribution (SSD) Methods

In these methods the cumulative frequency of the sensitivity of a single species is plotted against the toxicant concentration at which each species begins to experience toxicity. Then the concentration that corresponds to protecting a certain percentage of species
is calculated e.g. PC50 (pink) and PC95 (orange)

Overview of the method for deriving toxicant GVs using a SSD method

Quality of data and EQs

• Data needs to be good quality

• Every data point that passes screening must
  be assessed

  • in AUS-NZ we use the assessment
    method of Warne et al. (2018) and
    Heemsbergen et al. (2009), adapted from
    Hobbs et al. (2005)

  • other data quality assessment methods
    exist

    • e.g. CRED (Moermond et al. 2016)

• Assesses experimental design; chemical, biological, and statistical methods used in toxicity tests

Why do we calculate a single toxicity value for each species (SSD)?

So that each species is given equal weighting (importance) in the species sensitivity distribution and DGVs. This also implies that all species are of equal importance.

Methods of obtaining a single value per species (SSD)

• Arithmetic mean

  • (a + b + c) / 3

• Geometric mean

  • anti-log [(log a + log b + log c)/3]

  • better measure of central tendency

• Lowest value

  • the lowest value for a species

Data manipulation rule:

• if there was only one TV for species - use this

• if there were several TVs for same endpoint, use geometric mean of values

• if there were several TVs for different endpoints, the endpoint with the lowest geometric mean is used to represent specieis

Workflow for Species Sensitivity Distributions

• After obtaining one value per species:

  • data entered into the SSDtools software (this replaces Burrlioz)

    • this calculates the cumulative frequency value for each species

    • plots the cumulative frequency values against the concentration at which the toxicity occurs

    • calculates the concentrations (guidelines) that theoretically should protect 99, 95, 90 and 80% of species

  • SSDtools can calculate the concentration that should protect any % of species or the % species that should be protected by any concentration
    

Cumulative frequency distributions (unlogged and logged)

Dat

Cumulative frequency = rank/(n + 1) e.g. for the first data point CF = 1/(13 + 1) = 1/14 = 0.07 or 7 %