Roundup is an endocrine disruptor and is toxic to human cells in vitro (tested in culture dishes in the laboratory) at levels permitted in drinking water in Australia, a new study has found. This is the first study to examine the effects of glyphosate and Roundup on progesterone production by human female cells in an in vitro system that models key aspects of reproduction in women. Glyphosate alone was less toxic to human cells than glyphosate in a Roundup formulation; both glyphosate and Roundup caused cell death which resulted in decreased progesterone levels – a form of hormone/endocrine disruption.