Warnings

Suppose your football coach exhorts the team with all the great coach clichés: “We win or lose together”, “There’s no I in ‘Team'”, maybe “We can still win if we pull together and give 110 percent in the second half”. Would anyone say this was a “warning”? But when Angela Merkel says Europe needs to work together to deal with the current influx of migrants, we get this headline in the Guardian:

 

guardian_merkel

It reminds me of the peculiar set of mandatory texts that were introduced for cigarette packets in the US in 1981: Among the warnings of carbon monoxide and foetal injury was this one:

SURGEON GENERAL’S WARNING: Quitting Smoking Now Greatly Reduces Serious Risks to Your Health.

“Greatly reduces serious risks to your health” doesn’t sound like a warning to me.

A walk in the park

A land without serious problems, Australia is worrying about the pampered dogs of a pampered movie star, who were smuggled in on a private jet without proper medical screening. Agriculture minister William Joyce has declared that the dogs must be returned to California forthwith or be put down. These dogs are of particular concern because they “come from a country that has rabies.”

The reason you can walk through a park in Brisbane and not sort of have in the back of your mind – what happens if a rabid dog comes out and bites me or bites my kid – is because we’ve kept that disease out.

Obviously he is not aware that Californians always put on their bite-proof body armour to protect themselves when they leave their fortified bunkers. Rabies is pretty much all anyone thinks about when they walk through a park in San Francisco.

Risk categories and e-cigarettes

I’ve been reading Kate Fox’s celebrated Watching the English, which is sort of a pop-sociological treatise on English customs, but somewhat hard to take for all its flattering the English in all the myths they cherish about themselves — including their supposed modesty and inability to accept compliments. (I was particularly astonished by her description of the supposedly considerate English drivers. Perhaps they treat other drivers with more respect than they can spare for pedestrians.)

Anyway, since I am intrigued by the way “e-cigarettes” — devices for inhaling an addictive drug — have managed to float free from drug regulations, not to mention the prohibition that usually gets slapped onto designer drugs, as well as from their association with increasingly illicit tobacco. Fox is a huge fan, and can’t understand how anyone could object:

These clever devices are a sort of glorified version of nicotine inhalators, which look and feel rather more like a real cigarette, and emit a totally harmless, odourless steam or vapour that looks a bit like smoke. Many people are now accustomed to seeing these electronic cigarettes, and know that they are harmless…

Some people, however, do not instantly grasp this… and I have been conducting informal cross-cultural research on their reactions. In England, there are the usual raised eyebrows, frowns, pursed lips, tuts and mutters… But in all the years that I have been using these e-cigarettes on public transport and in restaurants, pubs and other public places where smoking is banned, only one English person has ever actually ‘confronted’ me about it…

In almost all countries, this disapproval quickly turns to friendly laughter, or curiosity, once I have explained that my ‘cigarette’ is an innocuous electronic device. The only exception I have found so far is the US, where some people seem to object almost as much to completely risk-free e-cigs as they do to the real thing — an irrational reaction that brings to mind my favourite definition of Puritanism: ‘The haunting fear that someone, somewhere, may be having fun.’

(Mencken’s definition was actually “that someone, somewhere, may be happy”.) There’s a fascinating number of words about risk here: odourless, harmless [twice], innocuous, completely risk-free, irrational reaction. It brings to my mind the ridicule heaped upon the killjoys who suggested in the 1980s and 1990s that something as innocuous as sidestream tobacco smoke could harm people’s health. Now everyone accepts that sidestream smoke is highly toxic, but the completely unregulated mixtures of chemicals spewed out by e-cigarettes are supposed to be harmless. On the basis of advertising copy, so far as I can see.

In contrast to the anthropologist Kate Fox, mere epidemiologists do not describe the second-hand exposure to e-cigarette vapour as “completely risk-free”. Instead, they say things like

Schober et al. measured indoor pollution from 3 people using e-cigarettes over a 2-hour period in a realistic environment modeled on a café. They found elevated nicotine, 1,2-propanediol, glycerin, aluminum, and 7 polycyclic aromatic hydrocarbons classified as probable carcinogens by the International Agency for Research on Cancer in the room air.[…]

on average, bystanders would be exposed to nicotine but at levels 1/10th that of cigarette smoke (e-cigarette aerosol, 3.32±2.49 μg/m3; cigarette smoke, 31.60±6.91 μg/m3; P=0.008). Both e-cigarette aerosol and cigarette smoke contained fine particles …

So e-cigarette vapour contains known carcinogens and the addictive drug nicotine. It is known that persistent low-level exposure to nicotine can provoke nicotine dependence, particularly in adolescents, or predispose them to other drug addiction.

Some people choose to take that drug recreationally, and I don’t object to them having that right. But why would a scientist disparage other people’s unwillingness to accept these risks to support her habit as “an irrational reaction”?

Of course, I know why. It’s one of the standard clichés about scientists, that they use the pose of rationality to claim an authority that they have not earned, to pretend that their private caprices are facts. It is unprofessional, and it undermines the whole enterprise of science.

Building confidence in public health

The NHS informs concerned parents about vaccines:

The 4-in-1 pre-school booster is very safe. Before it was granted a licence, the safety, quality and effectiveness of the pre-school vaccine, like all vaccines, was thoroughly tested. It does not contain thiosermal (mercury).

A lot of parents are (probably unnecessarily) worried about thiomersal in vaccines. The reassurance from NHS would probably be more persuasive if they knew how to spell it. (Thiomersal is, confusingly, called “thimerosal” in the US, but not “thiosermal”.)

What does an anti-vaccine activist want?

With the swelling of interest in the anti-vaccine movement, inspired by the recent California measles outbreak, I’ve seen a number of opinions published similar to this one from Ian Steadman in the New Statesman

Then there’s also this to think about: if somebody’s distrust of scientific and/or political authority is so great, for whatever reason – maybe they’ve been scared by sensationalist stories in the media, or maybe they sincerely believe the government has no moral right to dictate health choices to citizens – that they’re willing to significantly increase their child’s risk of catching a (possibly fatal) illness, then calling them names and telling them scientists and politicians disagree with them is probably futile. Arguing that “the science is settled” with someone whose stance is predicated on the belief that the standards of proof used by scientists are flawed is definitely futile.

The article is excellent, but I don’t entirely agree with this sentiment. Living in Berkeley and Oxford, I have encountered some vaccine refuseniks, and it’s not clear to me that they have anything as definable as a belief about “the standards of proof used by scientists”. Rather, I think that they have a desperate need to feel special, protected not by mass vaccination — and definitely not by anything as infra dig as “herd immunity” — but by their special virtue, which may be Christian purity or organic health-food purity. Continue reading “What does an anti-vaccine activist want?”

The CDC misunderstand screening too

Last week I mocked the Spanish health authorities who refused to treat an Ebola-exposed nurse as a probable Ebola case until her fever had crossed the screening threshold of 38 degrees Celsius (or, in the absurdly precise American translation, 100.4 degrees Fahrenheit). Well, apparently the Centers for Disease Control in the US aren’t any better:

Before flying from Cleveland to Dallas on Monday, Vinson called the CDC to report an elevated temperature of 99.5 Fahrenheit. She informed the agency that she was getting on a plane, the official said, and she wasn’t told not to board the aircraft.

The CDC is now considering putting 76 health care workers at Texas Health Presbyterian Dallas hospital on the TSA’s no-fly list, an official familiar with the situation said.

The official also said the CDC is considering lowering the fever threshold that would be considered a possible sign of Ebola. The current threshold is 100.4 degrees Fahrenheit.

Most disturbing is the fact that they don’t seem capable of combining factors. Would it be so hard to have a rule like, For most people, let’s hold off on the hazmat suits until your fever goes above 38. But if you’ve been cleaning up the vomit of an Ebola patient for the past week, and you have any elevated temperature at all — let’s say 37.2 — it would be a good idea to get you under observation.

One-fifth of a teaspoon

I was brought up short by this odd sentence in a NY Times article on attempts to protect health-care workers treating Ebola patients:

At the peak of illness, an Ebola patient can have 10 billion viral particles in one-fifth of a teaspoon of blood. That compares with 50,000 to 100,000 particles in an untreated H.I.V. patient, and five million to 20 million in someone with untreated hepatitis C.

“One-fifth of a teaspoon” is an odd reference unit. I had to think a moment to realise that the reporter had presumably translated into American from Scientific the sentence

At the peak of illness, an Ebola patient can have 10 billion viral particles in one milliliter of blood.

As I discussed before, the partial conversion to the metric system has left fault lines between and within nations. And the attempt to cover over those cracks mechanically creates odd dissonances. Thus, the 19th century estimate of average human body temperature of 37 degrees Celsius (plus or minus about half a degree) gets turned into the incredibly precise sounding 98.6 degrees Fahrenheit. It makes as much sense as saying “28 grams of prevention are worth 454 grams of cure”.

If the reporter had thought about it, she might have translated less mechanically, writing “an Ebola patient can have 50 billion viral particles in a teaspoon of blood”. But that still leaves the weird resonance of “teaspoon of blood”. A millilitre can be water or blood or Martian atmosphere, but when I hear “teaspoon” I subliminally feel like it’s supposed to go in my tea, or cake, or soup. The thing that people like so much about these traditional units is their historical and narrative specificity, their attachment to human-scale measuring activities, but that also makes them awkward for transferring measurements between domains. I could state my height in furlongs, and my weight in grains, but I’ll just confuse people.

Before posting, I just wanted to check that I was right about the size of a teaspoon in milliliters. I asked Google, and received the information “1 Imperial teaspoon =5.91939047 millilitres”. So, first of all, I was surprised to learn — if indeed it is true — that the teaspoon has been standardised to the hundred-billionth of a litre. Second, I found the thought of “the imperial teaspoon” hilarious.

Political talk therapy

Two apparently unrelated items from Nick Clegg’s speech at the Liberal Democrats’ party congress: First the BBC quoted his exhortation to the party soldiers, that they should

go to the next election with their “heads held high”.

Then came his announcement of

the first national waiting time targets for people with mental health problems.

People with depression should begin “talking therapy” treatments within 18 weeks, from April.

Let’s see: If the depressed Liberal Democrats can get their talk therapy started in April, maybe they’ll hold their heads a bit higher by the 7 May election.

False positives, false confidence, and ebola

Designing a screening test is hard. You have a large population, almost all of whom do not have whichever condition you’re searching for. Thus, even with a tiny probability of error, most of the cases you pick up will be incorrect — false positives, in the jargon. So you try to set the bar reasonably high; but set it too high and you’ll miss most of the real cases — false negatives.

On the other hand, if you have a suspicion of the condition in a particular case, it’s much easier. You can set the threshold much lower without being swamped by false positives. What would be really dumb is to use the same threshold from the screening test to judge a case where there are individual grounds for suspicion. But that’s apparently what doctors in Spain did with the nurse who was infected with Ebola. From the Daily Beast:

When Teresa Romero Ramos, the Spanish nurse now afflicted with the deadly Ebola virus first felt feverish on September 30, she reportedly called her family doctor and told him she had been working with Ebola patients just like Thomas Eric Duncan who died today in Dallas. Her fever was low-grade, just 38 degrees Celsius (100 degrees Fahrenheit), far enough below the 38.6-degree Ebola red alert temperature to not cause alarm. Her doctor told her to take two aspirin, keep an eye on her fever and keep in touch.

She was caring for Ebola patients, she developed a fever, but they decided not to treat it like a possible case of Ebola because her fever was 0.6 degrees below the screening threshold for Ebola.

A failure of elementary statistical understanding, and who knows how many lives it will cost.