Tools

How do we assess toxicity?

For the realization of the studies, we have to our disposal some tools that used properly allow us to evaluate the toxicity of the substance we are studying for people, animals and the environment.

The expert knowledge achieved over the years is a tool that allow us to find the most accurate answer to the question we want to solve.

First of all, to start any study it is necessary to gather all exiting information about the substance we are studying. Apart from the specialized scientific literature, there are many databases that compile a lot of information about chemicals, these are some of the most used:

COMPUTATIONAL TOOLS

Once all the information found has been reviewed, we almost always find that some data is missing, and then is when computational tools that make reliable predictions of physicochemical and toxicological endpoints need to be used, these are the tools we use and some of the parameters they predict.

Mutagenicity
Carcinogenicity
Skin and Eye irritation/corrosion
Skin sensitization
Estrogenic or androgen disruption
Thyroid disruption

Ames test
Comet Assay in mouse (in vivo)
Skin irritation (rabbit in vivo)
Respiratory sensitization
Estrogen receptot alpha binding (human in vitro)
Androgen receptor inhibition (human in vitro)
Acute aquatic toxicity
Biodegradation

Mutagenicity (Ames test)
Carcinogenicity
Developmental Toxicity
Estrogen Receptor Relative Binding
Androgen Receptor mediated effect
Thyroid Receptor Alpha effect
Skin sensitization
Hepatotoxicity
NOAEL

Boiling Point
Dissociation constant (pKa)
Melting/freezing point
Solubility in organic solvents / fat solubility
Vapor pressure
Water solubility
Bioaccumulation aquatic
Biodegradation in soil
Aquatic toxicity
Carcinogenicity
Developmental toxicity /Teratogenicity
Immunotoxicity
Irritation / Corrosion
Neurotoxicity
Repeated Dose Toxicity
Sensitisation
Toxicity to Reproduction
Dermal absorption

Carcinogenicity and Mutagenicity
In vitro mutagenicity (Ames test)
Skin irritation and corrosion
Eye irritation and corrosion
Skin sensitisation

Acute aquatic toxicity
Carcinogenicity (TD50)
Mutagenicity

Developmental Toxicity
Mutagenicity
Oral rat LD50
Melting point
Vapor pressure at 25ºC
Bioaccumulation factor
Daphnia magna LC50 (48hr)

Acute aquatic toxicity
Carcinogenicity (TD50)
Mutagenicity

Ames test
Environmemtal Toxicity
Log P and Solubility
Melting point
Skin sensitization
Non-genotoxic carcinogenicity
Genotoxic carcinogenicity
Acute  Aquatic toxicity
Developmental  and mitochromdial toxicity
Endocrine disruption

Acute toxicity
Eye injury and eye corrosion
Ames mutagenicity
Carcinogenesis
Drug-induced liver injury
Tetrahymena Pyriformis toxicity
Biodegradation
Endocrine Disruption

WEIGHT OF EVIDENCE

We often have at our reach more than one prediction of the same parameter and the best solution will be to make a combination of all the reliable predictions. This procedure of combining predictions is called weight of evidence and can be qualitative or quantitative. In the article “Quantitative wight of evidence method for combining predictions of quantitative structure-activity relationship models” (see reference to Publications & Training) describes a quantitative procedure applied to the Ames mutagenicity test prediction, which can also be used to combine prediction of other endpoints, we only need to know the sensitivity and specificity obtained in the validation of the model used to make each prediction.