Pharmaceutical poisoning is still a common childhood injury in the United States, as a new study shows that more than 500,000 children are exposed to pharmaceuticals on a yearly basis.

Researchers of the new study to be published in The Journal of Pediatrics noted that despite years of concerted prevention efforts like improved safe guards on packaging, such type of accidental poisoning is getting worse rather than better.

Dr. Randall Bond and colleagues from Cincinnati Children's Hospital Medical Center and the University of Cincinnati collected information about 544,133 children - 5 years old and younger - who had visited the emergency department (ED) because they may have been poisoned by medication.

The data researchers collected was from all cases reported to the American Association of Poison Control Centers between 2001 and 2008. This was done as means to find a way to come up with continued poison prevention methods.

In hopes of doing so the authors of the research organized the data according to medication type and whether the exposure was caused by the child self-ingesting the medication or by a dosing error.

The researchers found that 95 percent of ED visits was a result of self-ingestion.

Moreover, prescription drugs accounted for 55 percent of those visits, 76 percent of hospital admissions, and 71 percent of significant injuries.

The biggest impact, however, came from opioid-containing pain medications such as oxycodone, morphine, codeine, and sedative hypnotics such as muscle relaxants, sleep aids, and cardiovascular medications, according to researchers.

The problem of pediatric poisoning in the U.S. is getting worse, not better, Bond said in a statement.

Researchers found that overall, there was a 22 percent increase in the exposure for this age group to such kinds medications - even though the number of children in the U.S. under the age of 5 years increased only 8 percent during the study period.

The authors believe this increase is because there is a greater availability of, and access to, medications in the child's home. Effective poison proofing may have plateaued or declined in recent years, the authors said.

Prevention efforts of parents and caregivers to store medicines in locked cabinets or up and away from children continue to be crucial, Bond added. However, the largest potential benefit would come from packaging design changes that reduce the quantity a child could quickly and easily access in a self-ingestion episode, like flow restrictors on liquids and one-at-a-time tablet dispensing containers.

Bond recommended that such changes should be applied to both adult and pediatric products and to over-the-counter and prescription products.