Toxicology

Toxicology

Is the study of the adverse effects of chemicals on living organisms

Toxicologist

Is trained to examine the nature of those effects (including their cellular, biochemical, and molecular mechanisms of action) and assess the probability of their occurrence.

Ebers Papyrus

One of the oldest known writings, contains information pertaining to many recognized poisons, including hemlock, opium, and metals such as lead, copper, and antimony.

Mechanistic Toxicology

An area of toxicology wherein toxicologist identifies the cellular, biochemical, and molecular mechanisms by which chemicals exert toxic effects on living organisms.

Descriptive Toxicology

Deals with the toxicity testing, which provides information for safety evaluation and regulatory requirements.

Regulatory Toxicology

Regulatory toxicologists both determine from available data whether a chemical poses a sufficiently low risk to be marketed for a stated purpose and establish standards for the amount of chemicals permitted in ambient air, industrial atmospheres, and drinking water.

Forensic Toxicology

Is a hybrid of analytic chemistry and fundamental toxicologic principles that focuses primarily on the medicolegal aspects of the harmful effects of chemicals on humans and animals.

Clinical Toxicology

Is concerned with disease caused by or uniquely associated with toxic substances.

Environmental Toxicology

Focuses on the impacts of chemical pollutants in the environment on biological organisms, specifically studying the impacts of chemicals on nonhuman organisms such as fish, birds, terrestrial animals and plants.

Ecotoxicology

Focuses specifically on the impacts of toxic substances on population dynamics in an ecosystem.

Developmental Toxicology

Study of adverse effects on the developing organism that may result from exposure to chemical or physical agents before conception (either parent), during prenatal development or postnatally until the time of puberty.

Teratology

Is the study of defects induced during the development between conception and birth.

Reproductive Toxicology

It is the study of the occurrence of adverse effects on the male or female reproductive system that may result from exposure to chemical or physical agents.

Toxicity Assessment

Is the process of determining the relationship between the exposure to a contaminant and the increased likelihood of the occurrence or severity of adverse effects to people.

Acute Effects

Short term, appear shortly after exposure. Can be from single exposure.

Chronic Effects

There is a latency, a long period of time before you see the effect.

Poison

Any agent capable of producing deleterious responses in a biological system.

Toxin

Generally refers to toxic substances that are produced by biological systems such as plants, animals, fungi, or bacteria that are poisonous to other organisms.

Toxoid

A toxin that has been rendered nontoxic but still capable of eliciting the formation of protective antitoxin antibodies; used in vaccines.

Toxicant

Is used in speaking of toxic substances that are produced or are a by-product of human activities.

Toxemia

Abnormality associated with certain infectious diseases which is caused by toxins or other noxious substances released by microorganisms circulating in the blood.

Inhalation

For substances that are in the gas phase and very fine solid or liquid particles. (Through the respiratory system, pulmonary route)

Skin absorption

Usually common for liquids, solutes in solution, semisolids. (Percutaneous route)

Ingestion

Solids, usually contaminated food. (through mouth, oral route)

Injection

Infrequent route of worker chemical exposure.

Toxicity

Is defined as the degree to which something is poisonous. It is related to a material's physical and chemical properties.

Toxic Agent

Refers very generally to a material or factor that can be harmful to biological systems.

Spectrum of Toxic Dose

Describes the toxicity or hazards that are related to exposure to a particular chemical.

Dose

Is defined as the mass of chemical received by the animal or exposed individual.

Dose

Is usually expressed in units of milligrams per kilogram of body mass (mg/kg). Others used ppm.

Hazard Identification

Determines whether exposure to a contaminant causes increased adverse effects towards humans and to what level of severity.

Dose-response Evaluation

Uses quantitative information on the dose of the contaminant and relates it to the incidence of adverse health in an exposed population.

Dose-Response Relationship

The characteristics of exposure and the spectrum of effects come together in a correlative relationship customarily.

EDf

Effective dose for f percent of population. Reversible response.

TDf

Toxic dose for f percent of population. Undesirable response that is irreversible.

LDf

Lethal dose for f percent of population.

Graded Response

The individual dose-response relationship, which describes the response of an individual organism to varying doses of a chemical.

Quantal Dose-response Relationship

Characterize the distribution of responses to different doses in a population of individual organisms. (All or Nothing Response)

LD50

The point in the graph corresponds to the midpoint (inflection point) where 50% of the subjects are killed which is administered by any of a variety of methods. The unit is mg/kg.

LD95

Point at which 95% of the subjects are killed or 5% remained.

NOAEL

No Observed Adverse Effect Level.

LOAEL

Lowest Observed Adverse Effect Level.

Reference Dose (RfD)

Acceptable daily intake that is likely to be without appreciable risk.

LC50

The concentration of a chemical in an environment (generally air or water) which produces in 50% of an exposed population of test animals in a specified time frame. The unit is mg/L.

Chemical Allergy

Is an immunologically mediated adverse reaction to a chemical resulting from previous sensitization to that chemical or to a structurally similar one.

Chemical Idiosyncrasy

Refers to a genetically determined abnormal reactivity to a chemical.

Immediate Toxic Effects

Occur or develop rapidly after a single administration of a substance.

Delayed Toxic Effects

After lapse of some time.

Local Effects

Occur at the site of first contact between the biological system and the toxicant.

Systematic Effects

Require absorption and distribution of a toxicant from its entry point to a distant site, at which deleterious effects are produced.

Chemical Interaction

When a person simultaneously takes more than one drug, the combination may or may not alter the effects of each chemical.

Additive Effect

When the combined effect of two chemicals is equal to the sum of the effects of each agent given alone.

Synergistic Effect

The total effect is greater than the sum of the effects of each separately.

Potentiation

Occurs when one substance does not have a toxic effect on a certain organ or system but when added to another chemical makes the chemical much more toxic.

Antagonism

An active substance decreases the effect of another active one.

Functional Antagonism

Occur when two chemicals counterbalance each other by producing opposite effects on the same physiologic function.

Chemical Antagonism or Inactivation

Is simply a chemical reaction between two compounds that produce a less toxic product.

Dispositional Antagonism

Occurs when the absorption, biotransformation, distribution, or excretion of a chemical is altered so that the concentration and/or duration of the chemical at the target organs are diminished.

Receptor Antagonism

Occurs when two chemicals that bind to the same receptor produce less of an effect when given together than the addition of their separate effects or when one chemical antagonizes the effect of the second chemical.

Relative Toxicities

Refers to the 'lethal' effect of a substance to the affected organism.

Super Toxic

Where a few drops or less would be fatal.

Very Toxic

Few drops or a little more than a super toxic substance would be lethal.

Slightly Toxic

Could require a quart or more to kill an affected organism.

Reversible

When there is no lasting effect from the exposure to the toxin.

Irreversible

If the effect of the toxin/toxicant is permanent.

Carcinogen

Causes cancer.

Mutagen

Causes chromosome damage.

Reproductive Hazard

Damage to the reproductive system.

Teratogen

Causes birth defects.

Dermato Toxic

Affects the skin.

Hemotoxic

Affects the blood.

Hepatotoxic

Affects the liver.

Nephrotoxic

Affects the kidneys.

Neurotoxic

Affects the nervous system.

Pulmonotoxic

Affects the lungs.

Hypersensitivity

When an organism is highly sensitive or reactive to a toxicant even at very low dosages or concentrations.

Hyposensitivity

An organism has low sensitivity or reactivity to a toxicant even at lethal or high doses.

Pharmacokinetics

The absorption, distribution, metabolism and excretion of chemicals through the (human) system.

Detoxification

Is the biotransformation of chemicals into something less harmful storage in fatty tissue.

Immunity

Is a series of delicately balanced, complex, multicellular, and physiologic mechanisms that allow an individual to distinguish foreign material from 'self' and to neutralize and/or eliminate that foreign matter.

Immunosuppression

May result in repeated, more severe, or prolonged infections as well as the development of cancer.

Immunocompetence

The ability of the body to recognize and react with multiple foreign substances.

Immunoassays

Extremely sensitive tests that permit rapid and accurate measurement of trace antigen or antibody.

Immunoenhancement

May lead to immune-mediated diseases such as hypersensitivity responses, and if some integral bodily tissue is not identified as self, an autoimmune disease may be the end result.

Innate Immunity

Which eliminates most potential pathogens before significant infection occurs, includes physical and biochemical barriers both inside and outside of the body as well as immune cells designed for specific responses.

Acquired Immunity

Involves producing a specific immune response to each infectious agent (specificity) and remembering the agent so as to mount a faster response to a future infection by the same agent (memory).

Autoimmunity

Occurs when the reactions of the immune system are directed against the body's own tissues, resulting in tissue damage and disease.

Antigen

A nonself-molecule, including foreign DNA, RNA, protein, carbohydrates, and even mutated self-proteins, that can be recognized by the immune system. Each antigen is recognized by specific antibodies produced by B cells.

Acute Toxicity

An adverse effect that has a rapid onset, short course, and pronounced symptoms.

Cancer

An abnormal growth process in which cells begin a phase of uncontrolled growth and spread.

Carcinomas

Cancer of epithelial tissues. Ex. Lung cancer and skin cancer.

Chronic toxicity

An adverse effect that frequently takes a long time to run its course and initial onset of symptoms may go undetected.

Genotoxic

Toxic to the genetic material (DNA).

Initiator

A chemical that starts the change in a cell that irreversibly converts the cell into a cancerous or precancerous state. Needs a promoter to develop cancer.

Leukemias

Cancers of white blood cells and the tissue from which they are derived.

Lymphomas

Cancers of the lymphatic system. Ex. Hodgkin's disease.

Metastasis

Process of spreading/migration of cancer cells throughout the body.

Mutagenesis

Mutagens cause changes in the genetic material of cells.

Neoplasm

A new growth. Usually an abnormally fast-growing tissue.

Oncogenic

Causing cancers to form.