Bisphenol S, or BPS, is an organic compound used in plastics production and found in epoxies, glues and receipt paper, among other products.

The use of BPS has grown in the wake of environmental and health concern surrounding its close relative, BPA, but new research suggests Bisphenol S may not be any safer.

In a new study -- published in the journal PLOS Genetics -- UCLA researchers found BPS harms eggs at even lower concentrations than BPA. It's the latest study to suggest Bisphenol S has endocrine disrupting properties -- just like its chemical cousin.

Scientists exposed roundworms to levels of BPA and BPS similar to concentrations found in humans. Roundworms exposed to the chemicals experience lower fertility rates than control worms. Negative effects on fertility were measured at BPS concentrations lower than BPA, suggesting the newly popular BPA substitute may actually be more damaging to the reproductive system.

The roundworm reproductive processes disrupted by the plastics chemicals are shared by mammals.

"This study clearly illustrates the issue with the 'whack-a-mole' approach to chemical replacement in consumer products," Patrick Allard, assistant professor of environmental health sciences at the UCLA Fielding School of Public Health, said in a news release.

Companies are legally allowed to describe and advertise products containing BPS as "BPA-free."

"There is a great need for the coordinated safety assessment of multiple substitutes and mixtures of chemicals before their use in product replacement," Allard added. "But the good news is that a number of governmental programs and academic labs are now moving in that direction."