Definition of terms

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Name Description Related terms

A statistical test that compares the means of two samples in relation to the variability of the data.


A pre-formed solid of uniform shape and dimensions, often circular, with either flat or convex faces, the thickness being less than the diameter. Ready-to-use active constituent and inert ingredients are compressed into the tablet form, from which the active constituent dissolves or vaporises.

tablet for direct application

A formulation in the form of tablets to be applied individually and directly in the field and/or bodies of water, without preparation of a spraying solution or dispersion.

The APVMA formulation type code for tablet for direct application is DT.

take internally

To eat or swallow, or to take by mouth into the digestive system.

tank mix (or tank-mix)

Two or more pesticides mixed in the spray tank prior to application, as opposed to mixtures formulated by manufacturers.

tap density

Mass of the material divided by the volume occupied when compacted without pressure.

tap root

The prominent main root of some root systems (eg as seen in a carrot, parsnip or dock).


Something that a treatment is aimed at.

An area, building, animal, plant or pest that is to be treated with a pesticide.

target organ or target tissue

The organ(s) or tissue(s) in a plant or animal in which, owing to the chemical and kinetic properties of a xenobiotic agent, the pharmacological or toxic effects are seen.

In the context of residues, target tissues are the edible tissues selected for monitoring and compliance testing of total residues in edible commodities from treated animals. When the concentration of a marker residue in the target tissue complies with the relevant maximum residue limit, the corresponding concentration of total residues in the daily food basket (as measured by the estimated daily intake) does not exceed the acceptable daily intake.

target pest

The pest at which a pesticide application or other control method is directed.

target plants and target animals

The plants that will be deliberately exposed to agricultural chemical products and the animals that will be deliberately exposed to agricultural or veterinary chemical products during normal use according to label instructions or in an experimental study or clinical trial. Target plants or animals may be exposed by direct application of an agvet chemical product or through feeding a target animal with contaminated feedstuff. Target animals and plants should be identified by their species, class and breed (as appropriate).

target species

One or more organisms designated for a given pest management practice.

TCID50 or TCID50

The 50 per cent tissue culture infective dose.

The dilution of virus required to infect 50 per cent of the cell culture inoculated.

technical assessment

Has the same meaning as in regulation 8AS of the Agvet Code Regulations.

That section states:

If a person applies to the APVMA for an assessment of a technical nature (a technical assessment) before making an application, the APVMA may provide the technical assessment.

Examples:  Assessment of a trial protocol.

Assessment of data an applicant is considering submitting to the APVMA as part of a proposed application for registration of a chemical product or approval of an active constituent.

technical material

The commercial grade of the active constituent, as it comes from the manufacturing plant and before it has been formulated. The technical material comprises the active constituent and associated impurities and may also contain small quantities of additives necessary for stability.

The raw material used in preparing the agricultural or veterinary chemical formulation.

technical poison

Any substance or preparation included in Schedules 6 or 7 of the Standard for the uniform scheduling of drugs and poisons (SUSDP) or Standard for the uniform scheduling of medicines and poisons (SUSMP), as published by the Commonwealth of Australia under the Therapeutic Goods Act 1989 .

temperature inversion
temporary MRL

A maximum residue limit (MRL) established for a specified, limited period that is recommended under either of the following circumstances:

  • where only a temporary acceptable daily intake (ADI) has been estimated for the pesticide or contaminant of concern, or
  • where, although an ADI has been established, the use pattern is not sufficiently known or residues data are inadequate for proposing a maximum residue limit.

The property of a pesticide deposit to resist removal by weathering.


Congenital abnormalities or birth defects.


A substance that, if administered during the period of organogenesis (gestation), causes congenital malformations in the developing embryo of foetus (ie causes birth defects).


The development or malformation of a foetus, with structural abnormalities being present at birth or becoming evident shortly after birth.


The ability to cause harm to the foetus. The power or ability to cause terata.


The occurrence of structural malformations in a developing foetus when a substance is administered during pregnancy.


The study of the effect of chemicals on the structure and viability of developing embryos.


From s. 3 of the Agvet Code:

Does not include the Northern Territory.

test animals

Laboratory animals exposed to pesticides under standardised laboratory conditions, so that toxicity and hazards can be determined. Examples include rats, mice, rabbits, fish, birds.


A written or spoken statement of someone's experience, recommendation or opinion about some product or thing that does not have any associated organised investigations or trials, or evidence or data.

theoretical yield

The quantity of material or product that would be produced at an intermediate or final stage of manufacture, assuming that all starting materials, intermediates and final products meet their average specifications and that no loss or error occurs in production.


A chemical that has a remedial effect and is used for the purpose of combating plant or animal diseases.

therapeutic claim

A claim on a label that relates the nutrient(s) in a product to the prevention, treatment, alleviation or cure of a disease or condition (eg a calcium-rich diet prevents the progression, or reverses the progression, of osteoporosis).

Therapeutic Goods Administration (TGA)

The Therapeutic Goods Administration carries out a range of assessment and monitoring activities to ensure that the therapeutic goods (ie drugs and pharmaceutical products) available in Australia are of an acceptable standard. Their aim is to ensure that the Australian community has access, within a reasonable time, to therapeutic advances.

The regulatory framework is based on a risk management approach designed to ensure public health and safety. Essentially, therapeutic goods must be entered on the Australian Register of Therapeutic Goods before they can be supplied in Australia.

therapeutic index

The ratio of the dose required to kill or control a parasite and the minimum amount that is toxic to the host.

therapeutic pet food

A pet food that is used, or intended to be used, under veterinary supervision and/or has been formulated, or is represented, to provide a beneficial component in the prevention, treatment, alleviation, cure or recovery of a specific disease or condition (ie it meets the definition of a veterinary chemical product).


Of, about or related to heat.

thermal fogging

A method of applying a pesticide whereby applicators produce a fine space spray that will drift through the target zone. The fine spray persists for some time at suitable droplet densities to impact on the target.


Describes a class of bacteria that grow optimally at temperatures around 42˚C.

thickening agent

A material that increases the viscosity of a liquid.


From s. 3 of the Agvet Code:

Except where used as an object of the verb 'to do', includes:

  1. an animal, and
  2. information, and
  3. a document, and
  4. a substance.
threshold dose

The minimum dose of a substance necessary to produce a measurable effect in the test organism.

Also known as the 'minimum toxic dose'. No toxicity is observed below the threshold dose.

threshold level

That point at which a stimulus is strong enough to be perceived or produce a response.

The beginning point of some biological action.

The minimal effective dose that evokes a stated 'all or none' response.


The act whereby the soil is disturbed in the preparation of a crop seed bed. It is the start of a sequence of events in crop production, eventually ending in the crop being harvested. Tillage involves the ploughing, ripping, rolling, heavy discing or harrowing and rotavation of the soil.


The branch of a grass or cereal that emerges from the base of the main shoot.

tillered or tillering stage

The plant development stage when a plant produces additional shoots from a single crown, as in wheat.

timeshift application

From r. 3BA of the Agvet Code Regulations (unless the contrary intention appears):

  1. An application is a timeshift application if:(a) it is covered by subregulation (2); and
    (b) the applicant and the APVMA have agreed that it will be assessed in accordance with assessment periods set out in a project plan for the application agreed to by the applicant and the APVMA.
  2. An application is covered by this subregulation if:

    (a) the application is of a kind described in column 1 of item 1, 2, 3, 4, 5, 10, 11, 14 or 15 of the table in clause 2.1 of Schedule 6; and
    (b) if the application is of a kind described in column 1 of item 10 or 14—the APVMA has determined that at least 2 of the modules at items 2 to 10 of the table in Schedule 7 are necessary for the application.

Timeshift applications are assessed as item 27 applications. If you wish to submit a timeshift application you must seek Pre-Application Assistance.


A given number of infectious virus units per unit volume.

The concentration of a substance in solution or the strength of such a substance determined by titration.


Not susceptible to (or injured by) a pesticide application. For example, grasses may be tolerant of herbicides that are used to control broad-leaf weeds.

Able to endure infection by a particular pathogen without showing severe disease or giving little reaction to the effect of other factors (eg a virus that is tolerant of heat).

Same meaning as 'resistant'.

topical application

A pesticide that is applied from above, usually to the top or upper surface of a plant.

Treatment of a localised surface site, such as a single leaf blade or petiole or growing point.

Treatment of an animal by dusting, spraying or jetting that applies a localised treatment of the skin, eyes, or other specific external organs.

Direct application to a single organism (usually an insect).

topping up

for ectoparasiticide dips

The addition of water and undiluted product at the recommended rate to the sump or dip to return the volume of the dip to the starting level.

total acids

The total acidity of a technical material determined by direct titration.

total diet study

A study designed to establish the pattern of pesticide residue intake by a person consuming a defined diet.

total herbicide

A non-selective herbicide used in such a way as to kill all plant cover.

total herbicide treatment

Herbicide treatments that are made with the object of killing all vegetation present, for example on railway tracks, garden paths, roadsides and industrial estates.

total leviable value

From s. 3 of the Agricultural and Veterinary Chemical Products (Collection of Levy) Act 1994:

In relation to a chemical product for a particular period, means the sum of the leviable values in respect of the leviable disposals of the product that took place anywhere in Australia during that period.

total organic acids

The total amount (free or combined) of the active constituent and associated organic acids in a technical material or formulation.

total residue

In relation to veterinary chemicals in treated animals, the total residue of parent compound, free metabolites, and the metabolites that are covalently bound to endogenous material.

The relative and absolute amounts of each residue component will vary among the tissues with the amount of veterinary chemical administered and the time following the last administration of the veterinary chemical. Total residues are typically determined in pharmacokinetics studies using veterinary chemical that has been radiolabelled with carbon-14.

total vegetation control

The application of a single herbicide, or of multiple herbicides at one time or in sequence, to provide pre-emergence and/or post-emergence control of all plants.

total weed control

That form of weed control that involves killing all plant cover.


Poisonous. Able to cause injury to plants and animals, including people, by contact or systemic action.


A poisonous substance or preparation. A chemical that kills or causes an adverse effect in an organism when administered in small doses.


An inherent physiological or biological property of chemicals or biological agents that defines their capacity to do harm or produce injury to a living organism by means other than mechanical means. This property is measurable by laboratory techniques and may be expressed in either qualitative or quantitative terms. Adverse effects of a substance on a living organism are defined with reference to the quantity of substance administered or absorbed, the way in which the substance is administered (inhalation, ingestion, topical application, injection) and distributed in time (single or repeated doses), the type and severity of injury, the time needed to produce the injury, the nature of the organism(s) affected, and other relevant conditions.


The process of the uptake of potentially toxic substances by the body, the biotransformation they undergo, the distribution of the substances and their metabolites in the tissues, and the elimination of the substances and their metabolites from the body. Both the amounts and the concentrations of the substances and their metabolites are studied. The term has essentially the same meaning as pharmacokinetics, but the latter term should be restricted to the study of pharmaceutical substances.

toxicological endpoint

A qualitative or quantitative parameter analysed in experimental studies used to characterise the toxicity of a substance.

toxicologically significant impurity or toxic impurity

An impurity that has significant undesirable biological activity, often very highly toxic or sensitising to mammals at very low concentrations.


The study of the adverse effect of chemicals on living organisms.

trace elements

An element that is required in exceedingly small amounts.

tracking powder

A rodenticide contact formulation in powder form.

Trade Advice Notice (TAN)

A published report, with respect to a chemical product proposed for registration, which gives an assessment of the impact of residues of that product on Australia's exports of:

  • plant products derived from plants treated with the relevant chemical
  • animals and animal products that may contain residues following direct application to an animal
  • animal products that may contain residues of the chemical following the consumption of stockfood derived from crops treated with the chemical or from stockfood that may have contained residues from spray drift.

The TAN identifies Australia's trading partners for the commodity (by name and by volume); any maximum residue limits or tolerance levels set in these countries for the relevant chemical; and whether scientific data have been assessed to substantiate the limit of quantitation or any proposed export interval. A TAN is made available for public comment, and any comments received are considered by the APVMA in deciding whether or not it is satisfied that registration of the chemical product will not unduly prejudice trade.

trade criteria

A chemical product meets the trade criteria if use of the product, in accordance with instructions approved, or to be approved, by the APVMA, does not or would not, unduly prejudice trade or commerce between Australia and places outside Australia.

The trade criteria may be considered when the APVMA makes decisions about:

  • an application to register a chemical product—s. 14(1)(c)
  • varying relevant particulars and conditions for an approval or registration—s. 29(1)(c), s. 29A(2)(b)
  • affirming an active constituent approval, product registration—s. 34(1)(b)—and label approval at the conclusion of a reconsideration
  • preparing a standard for a listed registration—s. 8V(a)
  • considering the use of protected information when the information does not favour the applicant or holder—s. 34J(4)(b)
  • suspending or cancelling a product registration—s. 41(1)(b)
  • recalling a chemical product—s. 102(1)(a)
  • issuing a permit—s. 112(2)(d), s. 112A(2)(a)
  • suspending or cancelling a permit—s. 118(1)(b), s. 119(1)(b).

For a full definition of the trade criteria, see section 5C of the Agvet Code.

trade name

The proprietary name under which an agvet product is registered, labelled and promoted. This name may be used as, or as part of, the distinguishing name of the particular product. Trade names may be protected from unauthorised use by registration under patents and trade marks legislation.

transdermal use

The application of a veterinary chemical product to the skin, primarily for systemic effect.

transfer coefficient value

The area of treated foliage that a worker contacts when performing a specific re-entry activity in a given time period in square centimetres per hour (cm2/h).


The process by which a normal cell acquires the capacity for neoplastic or carcinogenic growth.

translocated herbicide

A herbicide that, when absorbed into the plant via the leaves or roots, moves within the plant and finally kills it. Translocated herbicides may be either moved in the phloem or xylem, but the term is frequently used in a more restrictive sense to refer to herbicides that are moved in the phloem.


The movement of soluble food materials through the tissues of higher plants (eg from the leaves to actively growing parts and storage organs and vice versa).

The botanical counterpart of the circulatory system in animals.


The normal loss of water through the above-ground parts of plants. Water vapour is lost through the stomata and, to a much lesser extent, through the cuticle.


A segment of DNA that is capable of inserting copies of itself into other DNA sites within the same cell.

trap crops

The early planting of a small portion of a crop or interplanting of a different crop to attract or divert an insect pest away from the main planting of the crop.


The term 'trial' tends to be used for field studies or clinical investigations.

It is often used interchangeably with the term 'study'.

Trial protocol

A document describing a trial design used to generate data to support applications for approval and registration or a permit.


Having three small leaflets—like a normal clover leaf.

trophic accumulation

The passage of a substance through a food chain, whereby it increases in concentration in the organisms at each successive step.

trophic level

One level of the hierarchical strata of a food web, characterised by organisms that are the same number of steps removed from the primary producers.


The swollen end of an underground stem, bearing buds in the axils of scale-like rudimentary leaves (eg potato).

Tukey's test of additivity

A test used in two-way analysis of variance to assess whether factor variables are additively related to the expected value of the response variable.


Causing or producing tumours.


The production of tumours.


A mass of new abnormal and disorganised tissue that grows independently of its surrounding structures and has no physiologic use. The mass is characterised by excessive and uncoordinated cell proliferation growth and abnormal differentiation. A tumour may be either benign or malignant.

Benign tumours morphologically resemble their tissue of origin, grow slowly (may also stop growing) and form encapsulated masses. They do not infiltrate other tissues, do not metastasise and are rarely fatal.

Malignant tumours resemble their parent tissues less closely and are composed of increasingly abnormal cells, genetically, morphologically and functionally. Most malignant tumours grow rapidly, spread progressively through adjacent tissues and metastasise to distant tissues.

tumour initiation

The first step in carcinogenesis, whereby a small number of cells (or one cell) are irreversibly changed due to genetic damage.

tumour progression

The stage in carcinogenesis when tumours acquire the features of malignant growth.

tumour promotion

The process by which initiated cells undergo clonal expansion to form overt tumours.


of the atmosphere

A quality or state in which the airflow at a given point changes constantly in velocity and direction (contrasted with laminar flow).

type code
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