Module 3: Health and Safety - IAFF

Student Text IAFF Training for Hazardous Materials: Technician©
The principal types of blood vessels are arteries, capillaries
and veins. Arteries carry blood away from the heart to
organs and tissues while veins carry blood back to the
heart. Capillaries are microscopic blood vessels with thin
walls through which oxygen, nutrients, and other materials
diffuse. The collection of blood vessels that provides the
body’s limbs with oxygen and nutrients is known as the
peripheral vascular system.
Toxic Effects
Toxic substances may affect the heart or peripheral vascular
system. As with many other body systems, the severity of
the effect is influenced by the concentration and duration of
exposure as well as pre-existing health conditions.
• Electrical conduction disturbances are abnormal
contractions of the heart muscle, such as potentially
life-threatening ventricular tachycardia. Materials that
can cause these effects include solvents, carbon disulfide,
Freon, and insufficient oxygen.
• Decrease in the contracting force of the heart muscle
results in an inadequate force to push the blood through
the vessels. Ethanol, cobalt, and trichloroethane (TCA)
can cause this effect.
• Enhanced arteriosclerosis or hardening of the arteries
can be caused by carbon monoxide and acrolein.
• Hypertension or high blood pressure can be due to a
variety of causes. It can lead to strokes, heart disease
and kidney failure. Exposure to lead and cadmium are
linked to hypertension.
• Hypotension or low blood pressure may be seen with
toxic exposures that result in dilation of the blood
vessels. If the body is unable to compensate for this
dilation, shock can result. Nitrates are known to cause
these effects.
Module 3: Health and Safety 3-41