Is bottled water really safe to drink? 5 things to know about a hidden hazard

Here are five things you need to know before you grab for that plastic water bottle again:

1. AVERAGE CONTAMINATION 

Through an analysis of 259 water bottles from 11 brands sold across nine countries, including the United States, scientists found 93 percent were contaminated with an average of 10.4 plastic particles per liter of water.

That’s twice the amount of contamination typically found in tap water.

"In this study, 65 percent of the particles we found were actually fragments and not fibers," lead researcher Sherri Mason told AFP.

2. MAJOR BRANDS TESTED 

Major brand names such as Aquafina, Dasani, Evian, Nestle Pure Life and San Pellegrino were among the water bottles tested.

3. CANCER? Previous research has linked synthetic chemicals often found in plastic to "certain kinds of cancer to lower sperm count to increases in conditions like ADHD and autism," Mason said, prompting calls for further studies on the possible health implications of plastics pollution.

4. WHY? According to the research, the plastic debris found in the water bottles included polypropylene, nylon and polyethylene terephthalate, which is used to make bottle caps. The particles are likely a result of the industrial bottling and plastic packaging process.

5. EFFECTS UNCLEAR 

But the effects of these chemicals on human health, scientists say, are still unclear.