A new research published in the journal Environmental Science and Technology revealed that the environmental impacts of drilling are worse than what is being reported.

The researchers from Duke University found out that 2 to 16 percent of hydraulic fracture oil and gas wells spill toxic substances each year. After examining spill data of four oil-producing states, they identified 6,648 spills that occurred between 2005 and 2014. The group created an interactive map that shows where and when the spill occurred.

Of the states examined, North Dakota had the highest rate of spills, with 4,453 incidents, while New Mexico had the least at 426. Pennsylvania had 1,293 and Colorado had 476 spills.

The data presented in the new study is in huge disparity with what the US Environment Protection Agency (EPA) reported in their previous study, which concluded that there were 457 fracking spills in eight states between 2006 and 2012.

Popular Science notes that the disparity is because EPA only took note of the leaks that occurred during the process of hydraulic fracturing while the new study considered all the spills from the drilling to the production.

According to the paper, across all four states, up to 75 to 94 percent of the spills occurred within the first three years of well life and 50 percent of the cases are storage and transport-related. In addition, many spill incidents happened at sites that had already experienced a spill, suggesting that these sites must be especially closely monitored.

Lauren Patterson, lead author of the study, said that spill reports across the four states differ because the reporting requirements are not standardized and the data collection and monitoring system is weak. In order to mitigate the risks of fracking and to conduct useful and accurate analysis, Patterson said states should have a uniform way of gathering data.

As this form of energy production increases, state efforts to reduce spill risk could benefit from making data more uniform and accessible to better provide stakeholders with important information on where to target efforts for locating and preventing future spills," Patterson said in a press release obtained by Science Daily.