Page 340 - Industrial Ventilation Design Guidebook

296 CHAPTER 5 PHYSIOLOGICAL AND TOXICOLOGICAL CONSIDERATIONS

FIGURE 5.48 Epidemiological data defining the relationships between smoking of cigarettes and carci-
noma of the lung, (a) Death rate from cancer of the lung and the rate of consumption of tobacco in the UK.
The rates are based on three-year averages for all years except 1947. (b) Relationship between lung cancer
mortality and previous cigarette consumption in sixteen countries. From left to right the solid dots below the
line (lower incidence) are from japan and USA and above the line (higher incidence) are from the Netherlands,
Austria and England/Wales, (c) Death rate from lung cancer, standardized for age among doctors smoking dif-
ferent daily numbers of cigarettes, (d) Death from lung cancer among doctors who had given up smoking ciga-
rettes for different periods (used with permission). | -| indicates data for <5, 5-9, 10-14, and >I5 years
64 142 144
since stopping smoking. ' " (Used with permission.)

on the cardiovascular system are secondary; i.e., a compound may affect
lipid metabolism and thereby amplify atherosclerotic alterations in the circu-
latory system.

Mechanisms of Cardiotoxicity Chemical compounds often affect the
cardiac conducting system and thereby change cardiac rhythm and force of
contraction. These effects are seen as alterations in the heart rate, conduction
velocity of impulses within the heart, and contractivity. For example, alter-
ations of pH and changes in ionic balance affect these cardiac functions. In
principle, cardiac toxicity can be expressed in three different ways: (1) pharma-
cological actions become amplified in an nonphysiological way; (2) reactive
metabolites of chemical compounds react covalently with vital macromolecutes