BPA in Plastic Bottles = testosterone problems in many men
That is a good warning to anyone who has been drinking out of plastic bottles…
workplace exposure to high levels of bisphenol A (BPA) to a variety of symptoms of male sexual dysfunction.
A new study has found that Chinese factory workers exposed to BPA had more than 7 times the rate of ejaculation difficulty than nonexposed workers. The exposed workers also had a rate of erectile difficulty that was more than 4 times greater, and a rate of reduced sexual desire and reduced satisfaction with sex life that was almost 4 times greater.
This is the first human study to confirm what has already been shown in animal studies, said the study’s lead author, De-Kun Li, MD, PhD, a reproductive and perinatal epidemiologist at Kaiser Permanente’s Division of Research in Oakland, California.
"Animal studies have shown that BPA has a whole range of adverse effects, including reproductive effects on the male and female, and possible effects on cancer and obesity, but the critics have been asking: ‘Where is the human evidence?’ " Dr. Li said. “Now we’re providing evidence from human studies to show that BPA does have an adverse effect on male reproductive sexual function so critics can’t dismiss this anymore.”
Increase the Urgency
Together, this animal and human research should signal the urgency of evaluating the safety of BPA in consumer products, said Dr. Li, adding that many manufacturers of plastic containers are already using BPA-free materials. He advised consumers to try to avoid, as much as possible, exposure to BPA until the completion of more research investigating BPA safety.
The study was published online November 10 in Human Reproduction.
Conducted between 2004 and 2008, the study looked at 230 employees of 4 factories in China producing BPA and epoxy resins. Workers were involved in most aspects of the manufacturing process, from laboratory to packaging to maintenance. A group of 404 control subjects consisted of factory workers matched for age, education, sex, and employment history who had no known exposure to BPA in the workplace, and their male spouses.
Researchers collected information on BPA exposure in a variety of ways. They reviewed the factory’s records, talked with factory leaders, and conducted a walk-through evaluation and in-person interviews to determine things like hygiene habits and the use of protective equipment. In addition, they carried out air sample monitoring and spot urine tests.
Measuring Sexual Function
To determine sexual health, they used the International Index of Erectile Function and the Brief Male Sexual Function Inventory. In addition to measuring sexual desire, erectile function, orgasmic function, and overall satisfaction with sex, they also looked at changes in sexual function since the subjects began working in a study factory.
Investigators also collected information on factors that can affect sexual function, including cigarette smoking, alcohol use, the presence of chronic disease, and exposure to other chemicals and heavy metals.
After adjustment for age, education, marital status, current smoking status, history of chronic disease, exposure to other chemicals, and employment history, the BPA-exposed workers had more than a 7-fold increased risk for ejaculatory difficulty (odds ratio [OR], 7.1; 95% confidence interval [CI], 2.9 - 17.6), compared with nonexposed workers.
The exposed workers also had an increased risk for erection difficulty (OR, 4.5; 95% CI, 2.1 - 9.8), reduced sexual desire (OR, 3.9; 95% CI, 1.8 - 8.6), and reduced overall satisfaction with sex life (OR, 3.9; 95% CI, 2.3 - 6.6).
There appeared to be a dose-response relationship between the exposure and all measures of sexual dysfunction except sexual desire, with increasing BPA exposure being associated with greater risk.
The relationship also appeared to develop rather quickly. Workers with 1 year of exposure or less experienced significantly more sexual dysfunction than nonexposed workers with the same duration of employment.
Dr. Li noted that the associations remained after excluding the more than 58% of BPA-exposed workers who had previously worked with other chemicals or heavy metals. Such broad exposure is common among workers in the chemical industry, said Dr. Li
Red Flag
The study results represent “a red flag” for the effects of BPA on human male sexuality, said Dr. Li. “Until this point, critics always asked for human data, saying you can’t extrapolate animal studies to humans.”
Asked why the study did not include testing of testosterone levels, Dr. Li said that the effect of BPA on hormone levels is a complicated issue that his research team will examine in future analyses.
To achieve sexual function, testosterone must bind to receptors in various organ tissues, explained Dr. Li. “High testosterone doesn’t automatically transfer into high sexual function,” he said. “You can have a whole bunch of testosterone in your blood but, if your binding mechanism is blocked, you still have a lower sexual function.”
According to background information in the study, BPA affects androgen receptors, male sex hormone levels, and male reproductive organs in rodents. This could disturb normal sexual functions, including libido and erectile and orgasmic functions.
The literature also shows that BPA can interfere with the function of Leydig cells, resulting in a reduction in testosterone biosynthesis, and it might adversely affect several tissue and cell structures of male sex organs through various mechanisms.
Male Target
BPA likely disturbs both male and female reproductive systems, but Dr. Li believes the effect of BPA is probably stronger in men. “The male target could include male adults and male offspring.”
BPA is found in plastic products, mainly polycarbonated plastics and epoxy resins. Consumer products such as baby bottles, plastic containers, and the lining of food and beverage cans contain BPA.
Exposure to some BPA is common. In a national sample of the American population, more than 90% of spot urine samples had detectable levels of BPA.
One of the limitations of the study was that it relied on self-reports of sexual dysfunction. It also did not take into account exposure to stress, which can affect sexual function, although there was no evidence that the exposed workers had a more stressful job environment than the control participants, said Dr. Li.
Now that the relationship between [sexual function and] exposure levels to BPA that are 50 times higher than normal has been established, “the safety issue of BPA at lower levels becomes a more urgent matter,” said Dr. Li.
He and his colleagues will be studying lower levels of exposure. They also aim to study the semen quality of men exposed to BPA and the effect BPA has on their male offspring.
The National Institutes of Health announced recently that it will devote $30 million to study the safety of BPA.
Provocative Article
Asked by Medscape Urology for a comment on this study, Richard Spark, MD, director of steroid research at Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, said that he found it a “very interesting and provocative” article.
However, he said the survey does not determine cause and effect. “It would have been wonderful if they could have drawn a tube of blood [to measure testosterone or estrogen levels] or anything that would relate to any hormonal abnormality, because if BPA is truly an endocrine disruptor in humans, as it is in animals, they had a golden opportunity to make it a slam dunk.”
He also would have liked to have seen more clarification on the effect of BPA on things other than testosterone production. “For example, ejaculatory function was impaired in this study. Ejaculatory function is a neurological function and it should not be affected too much by the ambient testosterone level.”
For his part, Dr. Li responded that the brain is affected by hormones, and BPA has been shown in animal studies to affect brain function.
The authors have disclosed no relevant financial relationships.
Hum Reprod. Published online November 10, 2009. Abstract
No more drinking soda from two liter plastic bottles or plastic lined aluminum cans. Ouch.
There’s no BPA in two-liter soda bottles. Anything with a recycling code of 1 should be BPA-free.
Hard polycarbonate can leach BPA; it carries recycling code 7 (“Other”). Ditch those Nalgene bottles!
I was in Target this evening and noticed that all their Nalgene bottles now carry a sticker that says “BPA Free”.
I guess they read my previous post.
[quote]jwillow wrote:
There’s no BPA in two-liter soda bottles. Anything with a recycling code of 1 should be BPA-free.
Hard polycarbonate can leach BPA; it carries recycling code 7 (“Other”). Ditch those Nalgene bottles!
[/quote]
Thanks for the heads up.
Just when you thought it was safe to go back in the water, er, I mean drink the water, along comes a new plastic threat - phthalates