Alternatives to cigarettes smoking could still pose a risk to human health due to overuse, according to a recent study.

Cigarette smoking kills approximately 440,000 Americans each year, according to the Centers for Disease Control and Protection. In order to overcome this addiction, many people resort to nicotine replacement therapies.

However, new research from the University of Miami suggests that small dosages of nicotine found in cigarette substitutes could be harmful to human musculoskeletal system, due to overuse.

"E-cigarettes are marketed as safe alternatives to cigarette smoking, however the harms associated with their overuse have not yet been widely investigated," Herman S. Cheung, senior author of the report, said in a statement. "We hope to increase awareness and promote further investigations into this field."

For the study, researchers investigated and summarized the last five years of studies, on the effect of nicotine on wound and skeletal healing processes in humans, via PubMed database.

Their findings show that nicotine can be beneficial at low dosages. For example, exposure to low dosages of nicotine promotes collagen production and skin wound repair. Yet at higher dosages cells involved in the wound and skeletal healing processes actually become ineffective. That's why overuse of nicotine-replacement, which still contains small amounts of nicotine, can present a health risk. However, what constitutes a low or high dosage depends on the cell type.

"Not all cells respond to nicotine in the same manner. What could be a low dosage for one is a high dosage for another," said Carlos M. Carballosa, doctoral student in the Department of Biomedical Engineering at the UM College of Engineering and primary author of this review. "The effects are to some extent, reversible, once exposure to nicotine stops."

The findings were recently published the Global Journal of Medical Research.