The image below is a standard warning label found on a bag of children's playsand.

Crystalline silica. A colorless mineral, also called quartz. It is an ingredient in sand and flint, which are used in making glass, cement, and concrete. Exposure to crystalline silica dust can cause lung diseases such as silicosis.

Crystalline silica up close.
1000 times magnification of sand dust sampled from a bag of common playsand. These particles are small enough to be trapped in lung tissue.

The State of California requires the above warning label on playsand containing crystalline silica. That is because much of the playsand found in today's stores is not natural sand, but actually derived from quarried quartz rocks. Children, who have developing lungs, breathe in crystalline silica dust as they play in the sand. Frequent sandbox play creates continued exposure to this known carcinogen.

Chapter 3. Safe Drinking Water and Toxic Enforcement Act of 1986 §12000. Chemicals Known to the State to Cause Cancer or Reproductive Toxicity.

What OSHA says about crystalline silica:

Silica, Crystalline Silicosis is a disabling, nonreversible and sometimes fatal lung disease caused by overexposure to respirable crystalline silica. More than one million U.S. workers are exposed to crystalline silica, and each year more than 250 die from silicosis. There is no cure for the disease, but it is 100 percent preventable if employers, workers, and health professionals work together to reduce exposures.

SILICA DUST EXPOSURES CAN CAUSE SILICOSIS

Every year two million workers in the U.S. are exposed to crystalline silica, which can cause silicosis, a disabling and sometimes fatal disease. About 300 deaths are attributed to silicosis annually. Inhaling airborne crystalline silica dust also has been associated with other diseases such as tuberculosis and lung cancer.

The Occupational Safety and Health Administration (OSHA) is determined to reduce the potential threat of silicosis. Crystalline silica has been identified as a priority rulemaking action. In the meantime, OSHA is conducting a national special emphasis program on silicosis to inform employers and employees about the occurrence and hazards of crystalline silica and ways to reduce exposure to the dust. The 25 states and territories that operate their own occupational safety and health programs have been encouraged to launch similar special emphasis activities on silicosis.

Crystalline silica, also known as quartz, is a natural compound in the earth's crust and is a basic component of sand and granite. Silicosis is a disease of the lungs caused by breathing dust containing crystalline silica particles. The dust can cause fibrosis or scar tissue formations in the lungs that reduce the lungs' ability to work to extract oxygen from the air. There is no cure for this disease, thus prevention is the only answer.

SYMPTOMS OF SILICOSIS

Early stages of the disease may go unnoticed. Continued exposure may result in a shortness of breath on exercising, possible fever and occasionally bluish skin at the ear lobes or lips. Silicosis makes a person more susceptible to infectious diseases of the lungs such as tuberculosis. Progression of silicosis leads to fatigue, extreme shortness of breath, loss of appetite, pain in the chest, and respiratory failure, which may cause death. Acute silicosis may develop after short periods of exposure. Chronic silicosis usually occurs after 10 or more years of exposure to lower levels of quartz.

U.S. Department of Labor Program Highlights OSHA Fact Sheet: 96-54 - 01/01/1996
Go to OSHA website to learn more

Health Effects of Inhaled Crystalline and Amorphous Silica (from the EPA website)

ABSTRACT: Recently, public concern regarding nonoccupational or ambient silica exposure, mainly to crystalline silica, has emerged making it important to evaluate background and ambient concentrations. Ambient emissions of silica rarely are estimated or measured in air pollution studies of particulate matter.

Crystalline silica is widely used in industry and has long been recognized as a major occupational hazard, causing disability and deaths among workers in several industries. This is a health risk assessment covering the causes and studies of crystalline silica exposure.

To view the entire report, click the link below:

EPA/600/R-95/115 (PDF) (Doc Stats: One 1.68MG

National Health and Safety Performance Standards [emphasis added]:

Standards For Sandboxes/Sand Play Areas

1) Sand play areas must be distinct from landings areas for any equipment such as slides, swings, etc.

2) All sandboxes shall be kept covered when not under adult surveillance. This covering shall be secured to prevent entry by children or animals, and sufficient to prevent contamination by solids or liquids.

3) Sandboxes shall be equipped with constant and effective drainage systems and be constructed to present no safety hazards.

4) Sand shall not be of the compacting type and should be replaced by fine pea gravel that is smooth surfaced. Any media placed in sandboxes shall present no preventable health or safety hazards by its nature or structure.

5) Sterilized sand or pea gravel should be obtained for sandbox use.

6) Sand that becomes contaminated shall be replaced with sterilized sand or pea gravel or the contaminant removed, where it is possible, to capture and dispose of all the contaminant. Treatment of sand with chemicals to attempt to sterilize it within the sandbox is not recommended.

7) Sandboxes/sand play areas shall be inspected for signs of contamination and safety hazards before each use.

8) Sand in boxes and play areas shall be replaced as needed and at least every two years.

National Child Resource Center