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2.5B ENVIRONMENTAL OCCUPATIONAL TOXICANTS, HEAVY METALS AND CHELATORS

PH RM COLOGY

TOXICOLOGY

OCCUPATIONAL

Chemicals found in the workplace.

ENVIRONMENTAL

Deleterious impact of chemicals on living organism present as

pollutants.

ECOTOXICOLOGY

Toxic effects of chemicals and physical agents on population

and communities of living organism within a specified

ecosystem.

OCCUPATIONAL TOXICOLOGY

Identifies agents

Defines safety

- Threshold limit values (TLVs)

Lays down guidelines to minimize absorption

POLLUTION

Industrialization

Technologic development

Urbanization

HAZARD VS RISK

Ability of agent to causeinjury

Primary consideration:

Use and exposure

Frequency of occurrenceof undesirable effectsarising from exposure.

EXPOSURE

ROUTES DURATION

Inhalation

Oral

Transdermal

Acute - single or multiplefor 2-3 days

Industry - occupational

Chronic - occupational oratmospheric

AGENT ORANGE VIETNAM WAR

HEALTH EFFECTS

3 million vietnamese people have been affected by Agent

Orange

Including at least 150,000 children born with birth defects

4.8 million Vietnamese were exposed to Agent Orange,resulting in 400,000 people being killed or maimed.

POLLUTION AND POLLUTANTS

Introduction of substances into the environment that alter its

physical, chemical and biological properties in such a way that

it is harmful to living organism.

ENVIRONMENTAL CONSIDERATION

Intake of a contaminant by an organism

Exceeds the latter's activity to metabolize or excrete substance

Chemical accumulates within the tissue of the organism

BIOACCUMULATION

Concentration of contaminant may be virtually undetected in

water

Magnified thousands of times as the contaminant passes up

the food chain

BIOMAGNIFICATIO

BIOMAGNIFICATION IN FOOD CHAIN

Polychlorinated biphenyls

undetectable in water

Phyloplankton X 1

Zooplankton X 49.2

Rainbow smelt X 416

Lake trout X 1932

Herring gulf X 49,600

Fish fry ???

AIR POLLUTANTS

TYPES & SOURCES OF AIR POLLUTION

Sulfur oxides

CO

Volatile organic compounds 5 pollutants - 98% of air

Particulate matter pollution

Nitrogen oxides

Others - Lead, Hydrocarbons, Cadmium, H2S, Ozone,

Polynuclear aromatic hydrocarbon, Indoor air pollution

POLLUTANTS

CO - 52%

SO - 14% Hydrocarbons - 14% Air pollution - 98%

NO - 14%

Particulate matter - 4%

SOURCES

Transportation

Industry

Generation of electric power

Space heating

Refuse disposal

Coal combustion

CO - 52%

PROPERTIES

Colorless, tasteless, odorless and non-irritating gas

Incomplete combustion

MECHANISMS OF ACTION

CO + HB = Carboxyhemoglobin

Cannot transport oxygen

Brain and heart most affected

CLINICAL EFFECTS

Psychomotor impairment

Headache

Loss of visual acuity

Tachycardia, tachypnea, syncope & coma

environment

water

soilair

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ENVIRONMENTAL OCCUPATIONAL TOXICANTS, HEAVY METALS AND CHELATOR

Convulsions, shock and respiratory failure

TREATMENT

Administration of oxygen

SO2- 14%

PROPERTIES Colorless, irritant gas

Combustion of sulfur - containing fossil fuels

MECHANISM OF EFFECTS

Moist membranes + SO2 -> sulfurous acid -> severe irritation

of the eyes, mucous membranes, skin

Bronchoconstriction & Pulmonary edema

TREATMENT

No specific treatment

NO2- 14%

PROPERTIES

Brownish irritant gas Fire and fresh silage-Silo filler's disease in farmers

Lung irritant - pulmonary edema

TREATMENT

Preventive and symptomatic

OZONE

PROPERTIES

Bluish irritant gas - occurs normally in the earth's atmosphere

SOURCES

Workplace - around high-voltage electrical equipment and

around ozone-producing devices used for air and water

purification.

Important oxidant found in polluted urban air.

Important absorbent of ultraviolet light.

CLINICAL EFFECTS AND TREATMENT

Mild exposure - URTI

Severe - Deep lung irritation - pulmonary edema

Airway hyperresponsiveness and airway inflammation

Acute intoxication - NO treatment

SOLVENTS

HALOGENATED ALIPHATIC HYDROCARBON

CCl4

Chloroform

Methyl chloroform Trichlorethylene

Tetrachloroethylene

USES

Industrial solvents

Degreasing agents

Cleaning agents

CLINICAL EFFECTS

CNS depression

Liver injury, kidney injury

Cardiotoxicity

Tetrachloroethylene -> Impaired memory and neuropathy

Carcinogenic effect - large safety margin

TREATMENT

No specific treatment

AROMATIC HYDROCARBON : BENZENE

ACUTE EFFECTS CHRONIC EFFECTS

CNS depression

Euphoria, nausea,

locomotor problems

Vertigo, headache

Coma

Very serious effects

Injury: Bone marrow

Increase incidence of

leukemia

TOLOUENE (METHYLBENZENE)

NO myelotoxic properties, nor associated with leukemia

CNS depressant

Organochlorine Organophosphorous Carbamate Botanica

ORGANOCHLORINE PESTICIDES

DDT (Chlorophenothane)

Benzene hexachloride

Cycylodienes

Toxaphenes

MECHANISM OF TOXICITY

Interfere with inactivation of -> rapid repetitive firing of most

neurons

EFFECTS CNS stimulation

Tremors and convulsion

TREATMENT

No specific treatment

PROPERTIES

Environmental toxicology

Persistent chemical

Slow degradation

Bioaccumulation in acquatic ecosystem is well documented

Once absorb in soil - do not readily desorb

ENDOCRINE DISRUPTORS Chemicals mimic, enhance, or inhibit a hormonal action

Estrogen-like or anti androgenic properties

Eg. Phytoestrogens, Mycoestrogens, Persistent organochlorin

agents such as DDT

Pesticides