TOXICOLOGY

Trina Redford, Industrial HygienistNational Naval Medical Center

Naval Business Bldg 615, 2nd 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

LocalSystemicCumulativePoisoning

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 ExposureAgeState of HealthPrevious ExposureEnvironmental FactorsHost Factors

Routes of Entry

PercutaneousInhalationOralOcular

Categories and Classification

Gases and VaporsAerosolsPulmonary IrritantsAsphyxiantsPrimary Anesthetics

Categories and Classification

Hepatoxic AgentsNephrotoxic AgentsNeurotoxic AgentsAgents Attacking Hematopoietic SystemAgents Damaging the LungsCarcinogens

Categories and Classification

MutagensTeratogensSensitization

Mechanisms of Toxicity

Summary

DefinitionDose ResponseTypes of ExposureTypes of EffectsFactors Affecting ToxicityCategories and Classification

Conclusion

Questions?Comments?

Thank you for your attention & participation