STATE OF THE ART OR WILLFUL IGNORANCE
“The Food and Drug Administration said Friday that it lacks scientific information to ban the chemical bisphenol A from food containers.”
Wall Street Journal, March 31, 2012
“…FDA supports reasonable steps to reduce exposure of infants to BPA in the food supply. …FDA will support changes in food can linings and manufacturing to replace BPA to minimize BPA levels…”
US Food and Drug Administration website, March 30, 2012.
While it is technically correct that the FDA did not ban bisphenol-A (BPA), the Wall Street Journal misled readers when it ignored the clear FDA statements that we need to reduce BPA exposure of our most vulnerable citizens. This is a prototype example of the spin-versus-spin arguments that characterize most of the environmental chemical debate. These arguments are not about truth. They are about control of public perception. It is time for willful efforts to skip the spin, outline the challenges, and answer the questions that affect the safety for our children and grandchildren.
The BPA debate centers around three types of data:
1. BPA promotes breast cancer in animals. Animals exposed to BPA, either in utero or through nursing from dams fed BPA, develop breast epithelial abnormalities and are more susceptible to breast cancer induction by the carcinogen dimethylbenzanthracene (DMBA). Like natural estrogen, BPA stimulates growth of human breast cancer cells transplanted into mice. These results parallel the effects of estrogens, which is not unexpected because BPA has been known to act as an estrogen since the 1930’s. Note, the concern is not that BPA by itself causes cancer but rather that it is an estrogen that promotes cancer.
2. In cell culture studies, BPA causes non-malignant human breast epithelial cells (obtained by fine needle aspiration from women volunteers) to grow faster and evade apoptosis (programmed cell death) a necessary step for radiation and drugs to kill tumor cells. These changes are sometimes called hallmarks of cancer because they are prerequisites for cancer to occur. BPA by itself will induce these changes. It is especially relevant that these changes occur in non-malignant cells because these are the cells that must be changed for breast cancer to occur.
3. Although most of us ingest BPA daily, it is metabolized quickly. Recent studies have shown that BPA in canned soups and similar products causes a spike in serum BPA, followed by a rapid fall back to pre-ingestion levels. Some critics conclude from this that BPA cannot be around long enough to cause harm. The opposing argument has two parts: First, clearance may not be functionally permanent. Most clearance is by conjugation (or chemical attachment) to glucuronate. This is a common way the body uses to clear hormones, chemicals, and drugs from the blood. However, the enzyme glucuronidase can free BPA from glucuronate, and biologically significant glucuronidase is present in many tissues. In the case of the breast, biologically active glucuronidase is present in mother’s milk and contributes to neonatal jaundice by deconjugating the baby’s bilirubin. It is difficult to expect that the BPA known to be in human breast milk would not be activated the same way.
Second, it is argued that BPA rises and falls too quickly to cause harm. However, endocrinologists have known for years that reproduction responds to spikes in hormone levels as much as to constantly elevated hormone levels. It may be that spikes, such as from a pre-adolescent eating BPA-rich food, would have a greater rather than a lesser effect.
These studies to not imply that BPA by itself causes breast cancer, but rather the estrogenic activity of BPA causes changes that promote breast cancer. The cancer promoting properties of estrogens are the reason millions of women discontinued menopausal hormone replacement therapy after the Women’s Health Initiative showed that combination estrogen plus progestin therapy increased breast cancer. Unfortunately, women living in the United States cannot decide to discontinue their exposure to BPA. BPA is present in food packaging, house dust, cash register receipts, etc. such that 95 percent of Americans and 90 percent of Canadians test positive for BPA in their urine.
Thirty years ago, Lippman and Bolan recognized the importance of cell culture “…in the analysis of oestrogen action in non-malignant tissue…” Working with non-malignant cells, we have catalogued six different major cell tests that are altered by BPA in ways that promote hallmark, cancer-like behavior in previously benign cells. The irony in this battle of spin is that if we had a drug that turned off cancer cells in culture as much as BPA turns them on, if we had data showing a mechanism of action like we have for BPA, and if we had the animal exposure data that already exists for BPA, the hypothetical drug would be lined up for clinical trials. Unfortunately, all of us are unwittingly already in the clinical trial.
It is time for responsible parents and grandparents to demand an end to the battle of spin. Calm minds must sort through the facts objectively and design and perform the studies still needed to resolve the questions.