“BPA produces an endocrine-disrupting effect and adversely affects male reproductive function.” – National Institutes of Health |
Dec 5, 2019 |
Washington State Univ. – Researchers have found that exposure to the endocrine-disrupting chemical bisphenol A (BPA) is far higher than previously assumed.
The study, published in the journal The Lancet Diabetes & Endocrinology on Dec. 5, provides the first evidence that the measurements relied upon by regulatory agencies, including the U.S. Food and Drug Administration, are flawed, underestimating exposure levels by as much as 44 times.
Patricia Hunt, Washington State University professor and corresponding author on the paper, said:
“This study raises serious concerns about whether we’ve been careful enough about the safety of this chemical. What it comes down to is that the conclusions federal agencies have come to about how to regulate BPA may have been based on inaccurate measurements.”
BPA can be found in a wide range of plastics, including food and drink containers, and animal studies have shown that it can interfere with the body’s hormones.
In particular, fetal exposure to BPA has been linked to problems with growth, metabolism, behavior, fertility and even greater cancer risk.
Despite this experimental evidence, the FDA has evaluated data from studies measuring BPA in human urine and determined that human exposure to the chemical is at very low, and therefore, safe levels.
This paper challenges that assumption and raises questions about other chemicals, including BPA replacements, that are also assessed using indirect methods.
Hunt’s colleague, Roy Gerona, assistant professor at University of California, San Francisco, developed a direct way of measuring BPA that more accurately accounts for BPA metabolites, the compounds that are created as the chemical passes through the human body.
Previously, most studies had to rely on an indirect process to measure BPA metabolites, using an enzyme solution made from a snail to transform the metabolites back into whole BPA, which could then be measured.
Gerona’s new method is able to directly measure the BPA metabolites themselves without using the enzyme solution.
In this study, a research team comprised of Gerona, Hunt and Frederick vom Saal of University of Missouri compared the two methods, first with synthetic urine spiked with BPA and then with 39 human samples.
They found much higher levels of BPA using the direct method, as much as 44 times the mean reported by the National Health and Nutrition Examination Survey (NHANES). The disparity between the two methods increased with more BPA exposure: the greater the exposure the more the previous method missed.
Gerona, the first author on the paper, said more replication is needed.
“I hope this study will bring attention to the methodology used to measure BPA, and that other experts and labs will take a closer look at and assess independently what is happening,” he said.
The research team is conducting further experiments into BPA measurement as well as other chemicals that may also have been measured in this manner, a category that includes environmental phenols such as parabens, benzophenone, triclosan found in some cosmetics and soaps, and phthalates found in many consumer products including toys, food packaging and personal care products.
“BPA is still being measured indirectly through NHANES, and it’s not the only endocrine-disrupting chemical being measured this way,” Gerona said. “Our hypothesis now is that if this is true for BPA, it could be true for all the other chemicals that are measured indirectly.” Source.
This study was supported by grants from the National Institutes of Health. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.
“BPA has been found to produce several defects in the embryo, such as feminization of male fetuses, [and] atrophy of the testes …” –National Institutes of Health
Adverse effects of BPA on male reproductive function
BPA is a ubiquitous environmental contaminant, resulting mainly from manufacturing, use or disposal of plastics of which it is a component, and the degradation of industrial plastic-related wastes.
Growing evidence from research on laboratory animals, wildlife, and humans supports the view that BPA produces an endocrine disrupting effect and adversely affects male reproductive function.
To better understand the adverse effects caused by exposure to BPA, we performed an up-to-date literature review on the topic, with particular emphasis on in utero exposure, and associated effects on spermatogenesis, steroidogenesis, and accessory organs.
BPA studies on experimental animals show that effects are generally more detrimental during in utero exposure, a critical developmental stage for the embryo.
BPA has been found to produce several defects in the embryo, such as feminization of male fetuses, atrophy of the testes and epididymides, increased prostate size, shortening of AGD, disruption of BTB, and alteration of adult sperm parameters (e.g.,sperm count, motility, and density). BPA also affects embryo thyroid development.
During the postnatal and pubertal periods and adulthood, BPA affects the hypothalamic-pituitary-testicular axis by modulating hormone (e.g., LH and FSH, androgen and estrogen) synthesis, expression and function of respective receptors(ER, AR).
These effects alter sperm parameters. BPA also induces oxidative stress in the testis and epididymis, by inhibiting antioxidant enzymes and stimulating lipid peroxidation.
This suggests that employing antioxidants may be a promising strategy to relieve BPA-induced disturbances.
Epidemiological studies have also provided data indicating that BPA alters male reproductive function in humans. These investigations revealed that men occupationally exposed to BPA had high blood/urinary BPA levels, and abnormal semen parameters.
BPA-exposed men also showed reduced libido and erectile ejaculatory difficulties; moreover, the overall BPA effects on male reproduction appear to be more harmful if exposure occurs in utero. The regulation of BPA and BPA-related products should be reinforced, particularly where exposure during the fetal period can occur.
The current TDI for BPA is proposed as 25 and 50 1-1g/kg bwt/day (European Food Safety Authority and Health Canada, respectively).
Based on the evidence available, we believe that a TDI value of 5 1-1g/kg bwt/day is more appropriate (the endpoint is modulation of rat testicular function). Certain BPA derivatives are being considered as alternatives to BPA.
However, certain of these related products display adverse effects that are similar to those of BPA. These effects should be carefully considered before using them as final alternatives to BPA in plastic production. Source.
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