Despite its popularity and its distribution in places such as Flint, Michigan, bottled water might not be as safe as you think.

A test conducted by California nonprofit Center for Environmental Health finds that two bottled water brands — Peñafiel, owned by Keurig Dr Pepper and Starkey, owned by Whole Foods — contain levels of arsenic that are higher than tap water, violating state guidelines as a result.

High levels of arsenic, California law states, can cause reproductive harm and cancer.  Products that violate recommended state levels of arsenic have to be labeled with a warning.

“Customers typically purchase bottled water at exorbitantly high costs with the assumption that it is safer and healthier to drink than tap water, unaware that they are ingesting an extremely toxic metal linked to birth defects and cancer,” said Michael Green, the organization’s CEO, in a statement.

Studies also show that it can cause hormone disruption and organ damage, especially in children.