Exposure to the bisphenol A (BPA) substitute, bisphenol S, could increase the aggressiveness of breast cancer by acting as an endocrine disruptor, just like BPA, according to American research presented over the weekend at ENDO 2017, the Endocrine Society's 99th annual meeting in Orlando, Florida. 

Researchers at Oakland University, USA, found that Bisphenol S (BPS) aggravated estrogen-receptor-positive breast cancers -- the most common kind -- by stimulating the proliferation of cancer cells.

After exposing breast cancer cells to BPS for six days, the researchers observed that this chemical substance could be just as dangerous at bisphenol A, by mimicking the effects of estrogen in cancer cells. The number of cancer cells increased by 12% in presence of low doses of BPS and by up to 60% when exposed to the highest doses. 

In fact, after 24 hours, BPS exposure heightened the protein expression in estrogen receptor alpha (ER alpha) -- present in two-thirds of breast cancers -- and in the BRCA1 gene, as did estrogen. According to the National Cancer Institute, 55% to 65% of women who inherit a harmful mutation in the BRCA1 gene will develop breast cancer.

With bisphenol A now banned in several countries, substitutes like bisphenol S (BPS) and bisphenol F (BPF) -- thought to be safer -- have instead been used in plastic materials like food packaging materials and thermal paper receipts. However, the potential dangers of these substitutes haven't been fully explored, and there is no legislation relating to their use.

In January 2015, a team of researchers at France's INSERM (French National Institute of Health and Medical Research) highlighted the potential danger of two substitute products for bisphenol A (BPA) -- bisphenol S (BPS) and bisphenol F (BPF) -- which were seen to provoke the same level of hormonal disruption in male cells as BPA.

Endocrine disruptors have been linked to diseases and defects such as diabetes, fertility issues and cardiovascular problems.

The research was presented at ENDO 2017, the Endocrine Society's 99th annual meeting, April 1-4, 2017, held in Orlando, Florida, USA.