Until about 1900, nearly all anthracite coal breakers were labor-intensive. The removal of impurities was done by hand, usually by boys between the ages of 8 and 12 years old known as breaker boys.

The use of breaker boys began in the U.S. around 1866.  The breaker boys would sit on wooden seats, perched over chutes and conveyor belts, picking slate and other impurities out of the coal. Breaker boys worked 10 hours a day for six days a week.

The work was hazardous. Breaker boys were forced to work without gloves so that they could handle the slick coal better. The slate, however, was sharp, and boys would leave work with their fingers cut and bleeding. Many breaker boys lost fingers to the rapidly moving conveyor belts, while others, moving about the plant, had their feet, hands, arms, and legs amputated when they moved among the machinery and accidentally slipped under the belts or into the gears. Many died when they fell into the gears of the machinery, their bodies only retrieved at the end of the working day. Others were caught in the rush of coal, and crushed to death or smothered. The "dry" coal kicked up so much dust that the breaker boys sometimes wore lamps on their heads to see, and asthma and black lung disease were common.

Public outrage against the use of breaker boys was so widespread that in 1885 Pennsylvania enacted a law forbidding the employment of anyone under the age of 12 from working in a coal breaker. But the law was poorly enforced, and many employers and families forged birth certificates or other documents so children could work