TOXICOLOGY

Trina Redford, Industrial Hygienist National Naval Medical Center Naval Business Bldg 615, 2 nd Fl.

Philadelphia, PA

Definition

 Study of adverse effects of chemicals (i.e. poisoning) on living organisms  Has the potential to produce injury to living things  The probability that injury will occur under the conditions and the manners in which the substance is to be used

Dose- Response Relationship

 The toxic potency of a chemical is defined by the relationship between the amount (the dose) of a chemical and the response that is produced in a organism

Types of Exposures

 Acute – (Short term) – A single exposure lasting less than 24 hours  Chronic – (Long term) – Exposures are essentially for the lifetime of the species  Subchronic – Repeated exposures of less than a lifetime (e.g. 3 months)

Dose Response Curve

Dose-Response Relationships

Types of Effects

 Local  Systemic  Cumulative  Poisoning

Types of Effects

 Local – The site of action takes places at the point of contact – The site: • skin, • mucous membrane of the eyes, nose, mouth, throat • or anywhere the along the respiratory or gastrointestinal system

Types of Effects

 Systematic – The toxic substance has been absorbed and distributed throughout the body

Types of Effects

 Cumulative Effects – Over a period of time, the material is only partially excreted and the remaining quanties are gradually collected – The retained toxic compound accumulates and becomes great enough to cause pathological response

Types of Effects

 Poisoning – A toxic substance is absorbed and distributed by the blood stream throughout the body – Absorption reaches a point where it causes impairment of physiological function

Factors Affecting Toxicity

 Rate of Entry and Route of Exposure  Age  State of Health  Previous Exposure  Environmental Factors  Host Factors

Routes of Entry

 Percutaneous  Inhalation  Oral  Ocular

Categories and Classification

 Gases and Vapors  Aerosols  Pulmonary Irritants  Asphyxiants  Primary Anesthetics

Categories and Classification

 Hepatoxic Agents  Nephrotoxic Agents  Neurotoxic Agents  Agents Attacking Hematopoietic System  Agents Damaging the Lungs  Carcinogens

Categories and Classification

 Mutagens  Teratogens  Sensitization

Mechanisms of Toxicity

Summary

 Definition  Dose Response  Types of Exposure  Types of Effects  Factors Affecting Toxicity  Categories and Classification

Conclusion

 Questions?

 Comments?

Thank you for your attention & participation