A factory producing cans lined with the chemical BPA, which has been used in metal cans since the 1950s.

A factory producing cans lined with the chemical BPA, which has been used in metal cans since the 1950s.


Stealth Chemicals: A Call to Action on a Threat to Human Fertility

In an interview with Yale e360, epidemiologist Shanna Swan talks about how falling sperm counts and other fertility problems are linked to chemicals in consumer products and explains why the Biden administration needs to follow Europe’s lead in restricting these substances.

Shanna Swan of the Mt. Sinai School of Medicine in New York City is a leading researcher into the effects of so-called endocrine-disrupting chemicals on human fertility. A 2017 paper she co-authored came to the startling conclusion that sperm counts among men in the industrialized world fell nearly 60 percent from 1973 to 2011, in part because of the effects on the hormonal system of chemicals widely used in consumer products. Other factors include obesity, smoking, and alcohol.

Shanna Swan

Shanna Swan

In her new book, Count Down, Swan makes her case against endocrine-disrupting chemicals. Her goal is to generate public concern about these substances and to spur government action to ban them. These chemicals include phthalates, used in plastics, floor coverings, personal care products, toys, and medical devices; BPA, used since the 1950s in plastic bottles and the linings of food cans; and flame-retardant chemicals called PBDEs, commonly used in upholstered furniture, mattresses, carpets, and children’s pajamas.

In an interview with Yale Environment 360, Swan explains why the United States lags far behind the European Union in regulating these chemicals, discusses what consumers — especially those trying to conceive — can do to limit their exposure to these substances, and describes why she is hopeful that the Biden administration will finally lead the U.S. government to begin reducing or eliminating these so-called “everywhere chemicals.”

Yale Environment 360: What are you asking the Biden administration to do? Are you proposing a public education campaign? Or are you talking about increased regulation?

Shanna Swan: Well, education is first, I think. Until people are aware of the problem, they’re not going to take action to reduce their own exposures or to move legislators to change regulations. And it’s not only the general public. It’s also, importantly, the medical communities, many of whom do not even teach anything about these problems.

I think what we’re trying to do is gain visibility, not only for the whole field of chemical regulation, which is huge, but also this particular set of reproductive outcomes that have been really overlooked and maybe denied. People are personally being impacted as more and more couples are having trouble conceiving or know somebody who’s having trouble. It’s coming home. People are starting to experience this, and I think now they’re more open to asking why.

“Chemicals that have been shown to alter hormones [should] not be permitted in household products.”

e360: Do you think legislation is necessary? If so, what measures would you ideally seek? Are you having any discussions with lawmakers on Capitol Hill?

Swan: Yes, I think revision of current legislation is necessary. I testified [in Congress] earlier about our studies and the dangers of phthalates and that was very effective, and it actually got a lot of phthalates [removed] from children’s toys. So, I think the evidence is convincing if we can present it. I think government agencies are looking to make changes and are open to making changes in a way they weren’t, certainly, over the last four years, and that maybe these findings are spurring them to move faster to do that. It’s very early days. But I’m optimistic. I think we may be able to do something more this time.

But aside from regulations on specific chemicals, we have to do something much broader and I think we have to change the burden of proof, as is done in Europe. In Europe under REACH [a European Union regulation on Registration, Evaluation, Authorization, and Restriction of Chemicals], chemicals must be shown to be safe before they’re put into products, but in the U.S., that’s not required. A substance can be added. It’s not restricted. It’s not tested. It goes into the product and then it goes into people, and then it’s left to people like me to conduct studies which will look for harm.

Then, on top of that, if we find something like BPA, which is harmful, and people ask that it be taken out, then the manufacturers can — and have — put in alternatives like bisphenol S and bisphenol F, which allows them to label the bottle as BPA-free, but does not protect the consumer, because this alternative bisphenol conveys the same risk.

e360: Is that what you mean by the so-called whack-a-mole approach to regulation, in which companies stop using certain chemicals because of regulation or public health concerns but substitute others that have not been fully tested but may be just as dangerous to health?

Swan: Exactly. And that’s been going on for a very long time. That would not be possible under a REACH-like alternative as is done in Europe.

Toys found to have extremely high levels of phthalates at the Consumer Council in Hong Kong.

Toys found to have extremely high levels of phthalates at the Consumer Council in Hong Kong. South China Morning Post/Contributor

e360: In your discussions with the EPA, are you presenting the REACH regulation as a way forward on this?

Swan: Yes. In particular, I am asking that chemicals that have been shown to alter hormones, the so-called endocrine-disrupting chemicals, not be permitted in household products because they have been shown to cause harm to human health, even at low doses. I’m asking that chemicals not be permitted in products that are hormonally active, that do harm at low doses, and that persist in the environment. That’s a tall order. Obviously, it will take time. And that will be facilitated by replacing the chemicals in commerce right now with alternatives that serve a similar function but do not have these health-damaging properties.

e360: Are such replacement chemicals readily available? Could the existing endocrine-disrupting chemicals be safely substituted?

Swan: I would have to say not yet, but some of them come under the rubric of green chemicals. Some do not. There’s a controversy about that term and what it represents. But there are definitely chemists who are actively seeking and have funding to develop alternative chemicals. This is a huge enterprise, obviously. It will take a lot of pressure, and there will be a lot of pushback from chemical companies that don’t want to make these changes. To me, that kind of effort requires huge public support. And the public won’t support this until they understand the problem.

That’s why I think we have to start with education. People get outraged that they’re supposed to scan these labels for chemicals they don’t understand and may not even be listed. I’d like to see a lot of outrage, and that’s what I’m trying to generate here so that [outrage] can motivate the development of safer chemicals and better legislation.

e360: What do you think the most effective way of generating that outrage might be? What facts would you seek to be communicated to the public in order to do that?

Swan: First of all, I think people have to acknowledge that they’re being impacted. Until recently, I was whistling in the dark because most people didn’t really feel that there was any problem. We’ve seen this with climate change; 40 years ago, some people were talking about climate change is coming and this is going to happen, but people were not experiencing it. I don’t think people are motivated to change until they actually feel threatened themselves. For example, they go to a sperm bank and it’s been closed because there aren’t enough sperm donors with adequate quality sperm to maintain the bank, which is happening. They go and attempt multiple times to get pregnant and don’t succeed with that. I think young people should be most concerned because this is about their fertility and their children’s fertility and future generations.

e360: You talk about the politics of inattention. Does that mean you believe the government just has not been paying attention to this issue, or is this a matter of deliberately looking the other way when there’s some prospect of having to place more regulation on business?

Swan: I think it’s both. I think that these problems have not been forced into regulatory consciousness. And when they are, there are huge lobbies from the chemical industry pushing back and making it very difficult to move forward. It’s a struggle. We saw it with tobacco and climate change, and now we’re going to be seeing it more and more in the area of regulation of endocrine disruptors.

“The attitude toward protecting human health in this way is very different in the EU than in the U.S.”

e360: Is regulating this industry going to be a particularly heavy lift in the United States because of a pro-business mindset?

Swan: Absolutely. And we see the differences. There are 11 chemicals that are banned from personal care products in the United States. There are over 1,000 in EU countries. There are just a huge number of differences in what’s permitted. The attitude toward protecting human health in this way is very, very different in EU countries and the United States.

e360: I’ve seen you quoted as saying that the current trend suggests that sperm counts might go to zero by 2045. Is that accurate?

Swan: Yes and no. If you extend the line of sperm counts for Western men, it hits zero in 2045. If that were to happen, the median sperm count would be zero, which means that half of men would be azoospermic — that is, having no sperm. The other half would have quite low sperm counts. However, that’s an extrapolation quite a way from the data, which is risky. It’s particularly risky for biological systems because when you approach a lower limit, the curve will have to flatten out.

I don’t actually believe we’re going to hit zero, but if we did, it would be very dire. Actually, where we are now is not good at all. A median sperm count of 47 million per milliliter, that sounds like a lot of sperm. It is a lot of sperm. But [in 1973 it was] at 99 million per milliliter. When you get below 40, several studies have shown, then you get to the point where it takes longer to conceive… and in 2011, that median was 47. That in itself, without extrapolating to zero, is very alarming.

“We have to do something pretty serious because manufacturers aren’t going to change unless they have to.”

e360: If people want to take immediate action themselves without waiting for government regulation, what could they be doing in terms of their own lives?

Swan: There are definitely things to do, and I would put them into two classes — things to do as an adult, and things to do if you’re thinking of getting pregnant or are pregnant. And that’s because the impact of these chemicals is far more significant and permanent when the impact is to the unborn child. For pregnant women or couples planning to conceive, it’s absolutely essential that they take certain steps.

These chemical exposures can be controlled primarily by being careful about what you eat. The first thing is, eat unprocessed foods. Ideally, you’d go to buy some organic foods. You cook them. You eat them. Nothing in that process comes in contact with plastic. Nothing comes in contact with bisphenol A in cans and so on. You can really lower your exposure by eating very simply, looking at the labels on cans.

Phthalates and bisphenols are not listed on cans, but other products are. Personal care products will have chemicals in them, and cleaning products will have chemicals in them. So be careful of those products. And when you store your foods, store them in glass. Heat them in glass. Get rid of your Teflon pans.

e360: Does the federal government have the greatest possibility of doing something about this?

Swan: I think we have to do something pretty serious from on top, because I don’t think manufacturers are going to change their behaviors unless they have to. I mean, why should they? They’re making a profit, presumably, and manufacturing these products that people want, presumably. And so why should they change that if they don’t have to?

So, yes, I think there has to be pressure from above. And there has to be pressure from below, because the pressure won’t come from above unless there is pressure from below. I think we have to squeeze this, if you will, from both ends.

This interview has been edited for length and clarity.