Prolonged exposure to hazardous substances can lead to various health consequences, but it is important to distinguish between short-term (acute) and long-term (chronic) effects.

- Chronic bronchitis (Option 1) is a long-term respiratory condition often caused by prolonged inhalation of irritants like smoke or dust. While chronic bronchitis is a serious condition, it primarily reflects chronic inflammation rather than a systemic long-term consequence like cancer.

- Cancer (Option 2) represents a serious long-term health consequence caused by prolonged exposure to certain hazardous substances, such as asbestos, benzene, or radon. These substances can cause genetic mutations and cellular changes that develop over years or decades, leading to malignancies.

- Acute respiratory distress (Option 3) is an immediate, short-term reaction to exposure and is not considered a long-term consequence.

- Contact dermatitis (Option 4) is a skin condition resulting from direct exposure and is generally a short- to medium-term allergic or irritant reaction, not a systemic or long-term health consequence.

Therefore, cancer is the best representation of a long-term health consequence due to prolonged exposure to hazardous substances because of its delayed onset and serious nature.

Reference: Harrison's Principles of Internal Medicine, 20th Edition, Chapter 383: Environmental and Occupational Lung Diseases, Page 2774.