The Physics Police

The Physics Police

Tuesday, December 24, 2013

Not So Habitable Early Universe

Abraham Loeb published a preprint titled The Habitable Epoch of the Early Universe.

He argues that early-forming stars could have cooked enough heavy elements rocky planets to form by 15 million years after the big bang. Ambient cosmic temperature would allow for liquid water on the surface of these planets. He claims that life could arise on such planets!

I'm skeptical of his model showing star formation this early, but let's grant that some few such early rocky worlds could have existed.

It turns out this "habitable epoch" is still far too short for the evolution of life to occur.

His Goldilocks epoch of 100 < (1 + z) < 110 corresponds to a time t after the big bang where:

That only leaves 2.317 million years for life to form in liquid water. Nowhere near enough time.

Even if we grant that single-celled life could miraculously evolve this quickly, and important precursor of life simply isn't present. Life needs an ordered source of energy to run its metabolic processes. The Sun or geothermal vents, for example.

This planet would not have a slow-burning sun by definition, because it lies in an active star-forming region. It would also lack geology because, again by definition, it's heated by the cosmic background.

Putting aside those problems, the paper draws an incorrect conclusion about the anthropic principle.
The possibility that the chemistry of life could have started in our universe only 15 Myr after the Big Bang argues against the anthropic explanation for the value of the cosmological constant.
Assume we have some "fossil" of life from 15 million years after the Big Bang. How does this argue against the fine tuning of lambda being explained by selection bias (the anthropic explanation)?

It may have been far from zero for these fossil creatures, but it's still close to zero for us.

No new mechanism for our value of lambda is being offered by these or any short-lived fossils.

Monday, December 23, 2013

Scaring Women for Profit

Laura Kiesel is a freelance journalist who recently wrote an article for Salon called Toxic tampons: How ordinary feminine care products could be hurting women. She argues that "dangerous chemicals" inside tampons and pads are being ignored. She's focuses mostly on dioxins.
... products such as maxi pads, tampons and douches ... contain potentially harmful ingredients including ... dioxin, which has been identified by the World Health Organization as a Persistent Organic Pollutant, a toxic chemical that persists in environments for long periods of time.
This information comes from a document titled Chem Fatale compiled by Alexandra Scranton of Women's Voices for the Earth. This document, too, focuses on dioxins but lists several preservatives and other ingredients found in feminine hygiene products that are allegedly bad for you.

I suspect the emphasis on "dioxins" has something to do with the way that word sounds. Even if you don't know what dioxins are, you must know they're dangerous! After all, it rhymes with "toxins". Of course they are actually toxins, as Kiesel and Scranton so forcibly point out.

But the question is, are they found in tampons, and at what concentration? Chem Fatale cites a 2002 study published in the journal Environmental Health Perspectives titled Exposure assessment to dioxins from the use of tampons and diapers.

This study detected very, very small traces of dioxins in both cotton and pulp products.
The refined exposure analysis indicates that exposures to dioxins from tampons are approximately 13,000-240,000 times less than dietary exposures.
It would be astounding if no dioxins could be detected, because these chlorine-containing organic molecules are easily detected in extremely small quantities. For better or for worse, dioxins exist wherever life is found, which is to say the entire surface of the Earth. If you want to live absolutely free of any dioxins, go find a planet without life, or better yet, a universe without chlorine.

Despite the inconsequentially low concentration of dioxins found in tampons, Scranton argues that there is still cause for concern.
However, the study authors did not account for the unique and highly permeable tissues of the vagina, and how that vaginal exposure may be different or even more potent than the dietary route of exposure.
If Scranton had actually read the study, she would have learned that dioxin exposure was calculated using the partition coefficient of dioxins in the tampon. That is, how much of the dioxins can leak out and be absorbed into the body. The study assumed 100% intake of bioavailable dioxins! It made no assumption whatsoever about the permeability of anyone's privates.

Not only is the concentration of dioxins in tampons low compared to dietary sources, but the bioavailability is low, too. Remember that mucous membranes in the gut are highly permeable in order to absorb nutrients! Bioavailability of nutrients and dioxins alike are increased by chewing, saliva, stomach acids, the mechanical churning of the gut, etc.

The study's methods are actually quite sound, and its conclusion is clear. Tampons are safe.
Our analysis indicates that the use of either tampons ... does not contribute significantly to dioxin exposures in the United States.
So, if tampons don't contribute significantly to dioxin exposure, then why make a fuss about it? Such unscientific fear mongering seems designed only to scare women. Now why would a group called the Women's Voices for the Earth (WVE) want to scare women?

Well, you can download their Non-Toxic Shopping Guide, which has 17 pages of reasons, from Archipelago Soy Wax candles to Zulu Lux Gluten-Free lipstick.

Laura Kiesel is correct when she says that WVE are "taking aim at the $3-billion-a-year feminine care industry". But their "aim" isn't to inform or improve women's health.

It's to get in on the profit.

This story is being picked up by websites like Reader Supported News. I find it especially ironic when this crowd, which usually remembers to "follow the money", is so quick to believe lies told to them by this small business.

For-profit lies aren't at all monopolized by big business and the political Right.

Laura Kiesel was kind enough to respond to my email, and put forth a defense of her article.

She argued that the 2002 study is:
... over a decade old. In the world of science, a decade is ancient history. This is why I searched for more recent studies and referred to the EPA report from just last year that concluded that dioxins could have serious health effects at even ultra-low levels of exposure--which you conveniently left out of the recap in your blogpost, probably because it would have completely undermined your stance
As it happens, I left this calculation out for brevity, not because it undermines my anything.

The quote about "ultra-low levels" actually comes from an Environmental Health News article by Marla Cone which, like the link in her article, refers to the 2012 EPA document Reanalysis of Key Issues Related to Dioxin Toxicity.

This document concludes (on page 44) that the No Observed Adverse Effect Level (NOAEL) is greater than 0.32 ng/kg-day. Those are your ultra-low levels, right there.
The 2002 study may be old, but it's the only shred of evidence Kiesel or WVE have cited, so I will continue to address its implications. The tampon brand with the highest concentration of dioxins was sample D from Table 4 on page 26 with 0.247 pg/g dioxin and weight 4.04 g.

Assuming 100% absorption by a 60 kg female, the dose from one tampon per day would be:

(4.04 g) * (0.247 pg/g) / (60 kg-day) = 0.00001663 ng/kg-day

That's about 20,000 times smaller than the NOAEL from the 2012 EPA document.

Nothing to be afraid of.

Saturday, December 21, 2013

Solar Power the World

Renewable energy is great. Producing more of the world's energy from renewable sources is crucial to reducing carbon emissions. In the long run, as fossil fuel prices rise, investments made in renewable energy will pay off.

Solar power is a promising renewable energy source. The last decade has seen a lot of investment in solar power. It has even been encouraged by government refunds here in the US. This has been especially effective, because it lessens the prohibitive up-front cost.

There's this popular info-graphic depicting the surface area required to power the wold with solar.

The first problem I'd point out is that the image is an equirectangular projection, which means it skews the relative area of different points. That's quite the wrong choice of map projection!

Second, this comical depiction ignores the problem of transmission. By concentrating the solar power generation far from population centers, loss during transmission would be staggering. Also, why not piggyback on the existing power grid infrastructure?

Pedantry aside, as I mentioned above, the challenge facing solar clearly isn't limited surface area, but up-front cost.

I gathered some statistics and did a little linear interpolation in order to hazard a guess at the price of photovoltaic solar panels per square foot in 2030, as indicated in green on this info-graphic.

((2030 - 2009) * ($2.90 - $1.94) / (1990 - 2009)) + $1.94 = $0.88

Then I calculated the cost in today's dollars to place an order for enough solar panels to power the world in 2030.

($0.88 ft-2) * (496805 km2) = $4.71 trillion

That sounds like a lot, but it's only a quarter of the projected GDP of China by that date.

Another important challenge to solar powering the world would be what to do about night time. Maybe we can all get electric cars. They could store power by day, and releasing some back into the grid at night.

This would, however, depends on significant improvements made in electric battery and/or fuel cell technology. While I think these are hugely worthy research goals, I can't help but think of the energy storage biology has already invented.

The cost to produce a calorie of heat from ethanol is about 1.01 calories of input in the form of farming, transportation, processing, etc. If those inputs could be supplied by photovoltaic power during the day, they would drain half of produced electricity, but provide a supply of ethanol to be burnt, carbon neutral, during nighttime.

This is also too good to be true, because you'd finally run into that surface area problem. There may be plenty of land available for photovoltaic, but presumably not enough land to grow crops enough to produce all that ethanol.

I guess we'll have to keep our fingers crossed for that energy storage breakthrough.

Actually, I've heard of one clever idea called solar thermal, where mirrors reflect sunlight to heat a giant tank of water, which is large enough to stay hot and provide some power throughout the night.

Monday, December 2, 2013

The Maillard Overreaction

The Millard Reaction is a chemical reaction between amino acids and sugar. It's responsible for the "golden brown and delicious" quality of baked foods Alton Brown so admires. It creates a wonderful panoply of chemicals, many of which are very good eats. Some less so, as evidenced by the acrid taste of charred meat.

One of these molecules, called 4-Methylimidazole (4-MeI), was studied in 2007 by the National Toxicity Program. In this study, rats and mice were exposed to very high doses in their food.
There was clear evidence of carcinogenic activity of 4-methylimidazole in male and female B6C3F1 mice based on increased incidences of alveolar/bronchiolar neoplasms.
These results were only seen for mice in the highest dosage groups, 625 μg/g and above.

In 2011, the California Office of Environmental Health Hazard Assessment (OEHHA) set the "No Significant Risk Level" (NSRL) of 4-MeI 29 μg per day. In accordance with Proposition 65, a big scary cancer warning must be printed on consumables that exceed the NSRL.

This posed a problem for Coke and Pepsi, which both use caramel color. These sodas contains more than the NSRL level of 4-MeI per bottle. Both companies had to change their ingredients or risk having a cancer warning slapped on the label.

It isn't clear to me how OEHHA arrived at this ridiculously conservative NSRL for 4-MeI. Thanks to Dr. James Coughlan via Chris Hamble for this calculation demonstrating its absurdity:
... the amount of 12-ounce cans a woman would have to drink, a day, for the rest of her life, in order to get to the carcinogenic levels of 4-Mel would top 37,000 cans. And for men, a whopping 95,000 cans.
That's an extrapolation based on the National Toxicity Program study, accounting for concentration and body weight. A 12-ounce can of soda is 335 grams. If that can contains 29 μg of 4-MeI, than the NSRL concentration for a beverage is 0.0866 μg/g. That's 86.6 parts per billion, if you like.

In reality, the FDA, European Food Safety Authority, and Health Canada all consider caramel color safe. This is because the dose of 4-MeI you get from the food additive equivocal to that you ingest from roasted foods, baked goods, grilled meats, etc.

It's even in coffee! Lojková et al. looked for 4-MeI in several off-the-shelf coffee products.

4-MeI ranged from 0.35 to 0.77 μg/g in roasted coffee from around the world.

That's between 4.04 and 9.98 times the NSRL concentration! So, does that mean...?

Yes, coffee is toxic sludge.

Anyway, Coke and Pepsi are both transitioning to a new, low 4-MeI formulation of caramel coloring.

In July, a watchdog group called the Center for Environmental Health conducted tests on Pepsi and Coke from all over the country. They found bottles sold outside California still contained traditional caramel color. These results were published July 3rd, accompanied by an hysterical press release and online petition demanding that Pepsi "clean up" the ingredients ahead of schedule.

The Associated Press ran a story based on this press release, which was quickly picked up by junk news outlets. I call them junk because they distort their readers impression of a story with misleading headlines. One such headline reads US group finds ‘worrying’ carcinogen levels in Pepsi. Nobody ever said the word "worrying" except the anonymous poster of this story. Nevertheless, this misleading headline appears on 1,720 web pages!

Junk syndication like this is how several people I know get their news. If you ask me, this does far more damage than drinking a goddamn Pepsi.

If you take away one lesson from all this, let it be a healthy distrust of headlines, especially from junk news outlets. They're incessantly deceptive.

And as always, be wary of black and white health claims made in absence of dosage. Some things give rats cancer in high doses. That doesn't mean they will necessarily harm humans in low doses.

We can be glad OEHHA is doing its best to protect our health without believing alarmist nonsense.

Sunday, December 1, 2013

Baking with Splenda

Splenda is the trade name for sucralose, an artificial sweetener. There are people out there who make a living by creating a fear-driven market for "chemical free" foods, include sugar substitutes like Stevia extract, Agave nectar, etc.

Sayer Ji is one such snake-oil salesman. His latest post is Sucralose's (Splenda) Harms Vastly Underestimated: Baking Releases Dioxin. He claims that a newly published study:
... reveals an extensive array of hitherto underreported safety concerns, not the least of which is the formation of highly toxic chlorinated compounds, including dioxins, when Splenda is used in baking...
The study in question is Sucralose, a synthetic organochlorine sweetener: overview of biological issues by Susan Schiffman, author of several Nutri/System Flavor books. It's safe to say she has a horse in the game, which explains the extreme lengths this critical review goes to expose any potentially harmful effects of sucralose. She describes potential byproducts from cooking with sucralose including "dioxin-like polychlorinated biphenyls" (dl-PCBs).

Her source for this claim is Unintentionally produced dioxin-like polychlorinated biphenyls during cooking by Shujun Dong which examined the byproducts from cooking with and without sucralose.

B1 is beef plus soybean oil. BS4 is B1 plus added Sucralose. BP5 is B1 plus 1,3-DCP.
The results clearly show that overall, the same (or fewer!) dl-PCBs were produced with the addition of sucralose, whereas a different organochlorine molecule (1,3-DCP) did cause higher dl-PCBs.

This demonstrates that knowing a molecule is an organochlorine does not imply it will necessarily result in elevated dl-PCBs as a byproduct of cooking. Chemistry is more complicated than that! This is sort of addressed in the conclusion of the study:
Sucralose and 1,3-DCP are only model chemicals for chlorine-containing compounds, which may be used during daily cooking processes. Thus, appropriate use of chlorine-containing additives and flavorings during cooking could help reduce the risk of human exposure to dl-PCBs.
You know what else is a chlorine-containing compound? Salt!

Salt is a chlorine-containing compound = deadly toxic sludge.
Oh no! Quick, buy some Agave nectar!