PRINCIPLES OF TOXICOLOGY

previously the number one cause of cancer deaths in women, now this dubious honor is being replaced
by lung cancer, as is the case in men. Women are also entering the industrial environment in increasing
numbers, pursuing occupations previously held predominantly by men. This now incites the question
of whether there will be a correlation between this increased smoking incidence among women and
the incidence of cancer from industrial chemicals.
9.2 MECHANISMS OF INDUSTRIALLY RELATED PULMONARY DISEASES
Irritation of Respiratory Airways
One of the most common toxicity manifestations from inhaled agents in industrial exposures is the
irritation of the airways, resulting in breathing difficulties and even death for the exposed individual.
Often, this response results from bronchoconstriction, as the airways react to diminish the extent of
the unwanted exposure. This can be a protective mechanism, if the affected person can quickly remove
himself/herself or be removed from the offending agent. Of course, diminished inhalation over any
extended period of time has obvious deleterious effects for the worker.
The chemical warfare agents, chlorine and phosgene, exert immediate toxicity by airway irritation.
If the level of exposure is sufficient, the exposed individual can die within minutes of the initiation of
exposure. Often a high dose exposure is accompanied by dyspnea (difficulty in breathing, either real
or perceived), cough, lacrimation (tears), nasopharyngeal irritation, dizziness, and headache. The dose
response for chlorine exposures is summarized in Table 9.1.
An interesting aspect of most industrial inhalation exposures involving the irritation of the airways
is that the symptoms appear very serious at first, but seldom result in permanent respiratory damage.
The coughing and choking are very alarming to both the affected individual and onlookers (including
medical personnel), and at least should result in the injury being taken seriously (which is often a
problem in industrial toxicity episodes). Chest X rays and pulmonary function tests should be
conducted on these individuals, in case there are permanent or late onset toxicity manifestations such
as pulmonary edema. Although most of these individuals will recover completely, many people have
died from irritation of the airways following industrial chemical inhalation, and every incident must
be treated as a serious episode. It is highly recommended that workers have a baseline pulmonary
function test on file with which to compare after an irritant exposure.
Fibrosis and Pneumoconiosis
9.2 MECHANISMS OF INDUSTRIALLY RELATED PULMONARY DISEASES 181
A variety of lung diseases resulting from the inhalation of dusts has been encountered in occupational
environments. The disease mechanism, known as fibrosis, results when the lung gradually loses
elasticity as a result of the pulmonary response to long-term dust inhalation. The disease condition is
referred to as pneumoconiosis, derived from the Latin and Greek root words pneumo, which means
breath or spirit, and coniosis, which means dust.
TABLE 9.1 Chlorine Dose–Response Relationships
40 ppm Pulmonary edema
>1000 ppm Immediate death