Toxicity
Benzoyl peroxide breaks down in contact with skin, producing benzoic acid and oxygen, neither of which is very toxic.The carcinogenic potential of benzoyl peroxide has been investigated. A 1981 study published in the journal Science found that although benzoyl peroxide is not a carcinogen, it does promote cell growth when applied to an initiated tumor. The study concluded, "caution should be recommended in the use of this and other free radical-generating compounds".A 1999 IARC review of carcinogenicity studies found no convincing evidence linking BPO acne medication to skin cancers in humans. However, some animal studies found that the compound could act as a carcinogen and enhance the effect of known carcinogens. Skin irritation
In a 1977 study using a human maximization test, 76% of subjects acquired a contact sensitization to benzoyl peroxide. Formulations of 5% and 10% were used.The U.S. National Institute for Occupational Safety and Health has developed criteria for a recommended standard for occupational exposure to benzoyl peroxide. Cloth staining
Contact with fabrics or hair, such as from still-moist acne medication, can cause permanent color dampening almost immediately. Even secondary contact can cause bleaching, for example, contact with a towel that has been used to wash off benzoyl peroxide-containing hygiene products. Reactivity
The original 1858 synthesis by Liebig reacted benzoyl chloride with barium peroxide, a reaction that probably follows this equation:

2 C6H5C(O)Cl + BaO2 → (C6H5CO)2O2 + BaCl2Benzoyl peroxide is usually prepared by treating hydrogen peroxide with benzoyl chloride under alkaline conditions.
Osteoporotic bone marrow defect is a condition which may be found in the body of the mandible. It is usually painless and found during routine radiographs. It appears as a poorly defined radiolucency (dark area) where there was a previous history of an extraction of a tooth. It may resemble a metastatic disease. It is a localized increase of hematopoietic bone marrow that creates a radiolucent radiographic defect. They occur more commonly in women in the midyears and show a predilection for the molar region of the mandible. They are especially common in extraction sites. Scattered trabeculae may extend short distances into the defect or, in some instances, through it, giving the defect a fairly characteristic appearance. Naturally there are no clinical symptoms. Cause
The cause remains unknown. Diagnosis
Differential diagnosis
This defect may easily be mistaken for a cyst or tumor. Biopsy is required to rule these out. Treatment
No treatment is required. References

Kahn, Michael A. Basic Oral and Maxillofacial Pathology. Volume 1. 2001.