Toxicology Icon Toxicology Evaluation

A toxicity assessment is an assessment done to evaluate the possibility that an adverse health effect, such as target organ damage, cancer, allergic responses such as dermatitis and asthma, to name a few, may develop resulting from human exposure to a substance.

The toxicity evaluation involves two steps:

  • hazard identification and;
  • dose-response evaluation

The questions are: Is the compound toxic and if so, at what dose and in what form can it harm?

Hazard identification includes researching the toxicity of the compound by reviewing mostly animal studies but also human epidemiological data.

Dose-response evaluation is more complicated as it involves developing dose-response information for a potential adverse effect. This assessment identifies the relationship between the dose of a substance and its potential for harming the exposed person.

This dose-response assessment is used to develop reference values (for example "acceptable daily intake", "permitted daily exposure", "reference dose" etc.) that are defined as doses below which harmful effects are not expected to occur under the identified exposure conditions. Generally, these exposure conditions include oral, inhalation or dermal exposure.

Understanding the hazards which are associated with a substance is essential for identifying and mitigating the risks.

Dr Williams will help:

  • Evaluate chemical toxicology and exposure risk.
  • Provision of toxicological support such as research and calculation of acceptable daily intake levels as well as occupational exposure limits. (see table 1 for an example).

Toxicity Table

Table 1: The characteristics of pharmaceutical compound potency and toxicity by category (adapted from Farris J.P., Ader A.W. & Ku R. History, implementation and evolution of the pharmaceutical hazard categorisation and control system. Chemistry Today 2006 24:2 5-10).

Toxicology Evaluation


Dr Haidee Williams offers specialist occupational medicine services with an interest in developing evidenced based safety, health and environment policies and programmes. Expertise includes medical examinations, medical adjudication, toxicology, health based risk assessments, hazardous chemical substances, hazard communication and training and guidance on H,S&E legal compliance requirements.


Tel: 087 809 0054
Twitter: @drhmwilliams