Officials identify what turned Venice's Grand Canal neon green

• Fluorescein is an organic fluorescent agent often used in diagnostic medical procedures and as a leak detector in underwater construction.
• The toxicity of fluorescein is low, per the NIH. The agency said water samples did not reveal any levels of toxicity in the canal.

What's next: Complete analyses of the samples are expected to be completed in the next few days, the regional environmental agency said.

• Venice authorities have opened an investigation into the source of the chemical.

What they're saying: Luca Zaia, president of Veneto Region, said on social media that the color posed no dangers of pollution to the public but officials were worried about copycats.

• "Venice, like other symbolic places of Veneto, has such visibility that gestures like this could become the showcase for more and more ‘characters’ looking for clamor," Zaia said.

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