Last year, Ella Atlas, PhD, of Health Canada, and her team published an article in Endocrinology that showed exposure to bisphenol S (BPS), a chemical used to replace the much-maligned bisphenol A (BPA), can encourage the formation of fat cells.
The researchers created a human cell model to test the effects of BPS exposure. They used human cells called preadipocytes – undifferentiated cells that can develop into fat cells – taken from the hip, thigh, or abdomen of female volunteers. Groups of cells were exposed to various concentrations of BPS during a 14-day period. For comparison purposes, some cells were exposed to the chemical dexamethasone instead because it triggers a known rate of fat cell formation and accumulation of lipids, or fat-like substances that collect in the blood and tissue.
Industry should be thriving to achieve safer replacement chemicals, however, it is hard to imagine a chemical that can be labelled “EDC free” due to the complexity of the endocrine system and the many nuclear receptors involved.
Researchers found that the cells exposed to the smallest amounts of BPS as well as the cells exposed to the highest concentrations exhibited the largest accumulation of lipids, while moderate amounts had a smaller effect. Exposure to even tiny amounts of endocrine-disrupting chemicals can interfere with the functioning of hormones, since small changes in hormone levels are designed to trigger adjustments in metabolism, respiration, heart rate, and other bodily functions.
“Since BPS is one of the replacement chemicals used in consumer products that are marketed as BPA-free, it is important to examine whether BPS acts as an endocrine-disrupting chemical,” Atlas says. “This study shows that BPS and BPA have similar effects on fat cell formation, lipid accumulation and expression of genes important for lipid metabolism.”
Concerns about BPA’s effects on health have led to stickers that proudly proclaim “BPA FREE!” and BPA substitutes like BPS, but a growing body of research is showing that just because something says it’s BPA free, it doesn’t mean it’s EDC free. Endocrine News spoke more with Atlas on her study and its implications.
Endocrine News: Can you give some background on your study? How did it come about?
Ella Atlas: My laboratory is conducting research on glucocorticoid mediated differentiation of fat cells for the last 15 years. Due to the increase in the obesity rates in the population, we became interested in the effects of environmental compounds, such as plasticizers, on fat tissue and on the metabolic function of the adipose tissue. We have done a lot of work on trying to understand the effects of BPA on adipocyte differentiation. When it was evident that BPA is being replaced with other bisphenols, we were interested to know whether some of the effects that were attributed to BPA can also be attributed to the replacement chemicals, as structurally they are very similar molecules.
EN: It seems BPS affects all kinds of functions, and now you’ve shown it can trigger fat cell formation? If BPS is left unchecked, what kinds of effects would we see in people?
EA: This was a study done in cells in culture. Therefore, although this result may raise some concern as to the possible effects in humans, we cannot relate the results to the human condition at this stage. More research needs to be done in order to obtain solid scientific evidence that chemicals such as BPA and BPS can indeed affect metabolism and fat accumulation in humans.
EN: You note the limitations of your study – limited number of subjects, high concentrations to reach significance. How do we move forward from here? What kinds of further studies are needed?
EA: In order to be able to better understand the basis for the underlying biological responses, and in order to be better placed to predict these effects, it is desirable to understand the mode of action and the molecular targets of these chemicals. In addition, experiments to better characterize the dose response, particularly by determining whether low dose effects are observed on metabolic end points, need to be conducted.
“Since BPS is one of the replacement chemicals used in consumer products that are marketed as BPA-free, it is important to examine whether BPS acts as an endocrine-disrupting chemical.”
EN: What should endocrinologists take away from your study’s findings?
EA: There is a lot we do not yet know about environmental impacts on the endocrine system. That being said, for BPA the effects from exposure are thought to be especially crucial during gestation and lactation. If this is the case with BPS as well – and there is some evidence in the literature that this may be the case – then women may wish to exercise caution during child bearing and lactation to reduce exposures wherever feasible.
EN: Do you see a chemical ever being developed to use in consumer goods that’s completely safe? Do you ever think there will be stickers on products that say “EDC free”?
EA: Industry should be thriving to achieve safer replacement chemicals, however, it is hard to imagine a chemical that can be labelled “EDC free” due to the complexity of the endocrine system and the many nuclear receptors involved.
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