Botanical Sexism Cultivates Home-Grown Allergies

https://blogs.scientificamerican.com/guest-blog/botanical-sexism-cultivates-home-grown-allergies/

by LanceTaylor • 7 years ago

68 34 7 years ago

blogs.scientificamerican.com

You ever see one of those titles where individually you know all the words, but don't know what they mean together?

manfredo2• 7 years ago

If by "batonical sexism" we mean the choice to use male trees instead of female trees because it'd be a burden to clean up parts of the female tree that drop to the ground seasonally. It's a straightforward tradeoff: use male trees that produce pollen (and make it worse for allergies) or use female trees that have to get cleaned up (or plant both, and deal with both problems).

EnderViaAnsible2• 7 years ago

As the article notes, planting both actually reduces one of the problems: pollen. Female plants attract and capture pollen. So you will slightly increase litter while moderately reducing pollen.

Additionally, as the article also notes, all allergens are not created equal. Pollen is mostly notable insofar as it is allergenic; planting trees with low or nor allergenic pollen uncouples "pollen" and "pollen that causes allergies" levels.

manfredo2• 7 years ago

So you will slightly increase litter while moderately reducing pollen.

I don't see any indication that the increase in litter would at all be of greater proportion than the decrease in pollen. Only that bit of pollen that gets blown to a neighboring female tree would get absorbed. Not even all of that, since presumably the majority would get blown off the tree. I can't see how any more than a single digit percent of the pollen would be captured, so people with allergies would still be affected.

The increase in litter would be significant if half the trees were female. On my college campus there were parts of the year where certain types of trees would drop seed pods and it littered the streets for the better part of a week. It'd take a significant amount of manpower to clean it up - probably a garbage-bag per tree - so we just left it outside and dealt with vegetation litter for a couple weeks.

Unless the article backs up the claim that the pollen reduction would be substantial and the increase in litter trivial it could still very well be that a mix of female and male plants does not prevent allergic reactions to such a degree that it's worth using a mix of plants.

arkades• 7 years ago

tl;dr

Male trees were planted disproportionate to female trees in urban settings because they didn't shed messy seeds. The preponderance of male trees increases the amount of pollen exposure. Author asserts this leads to an epidemic of allergies/asthma. Author asserts this indirectly leads to cancer.

Author fails to apparently take into account that although we are exposed to more male trees than female trees, our total tree (and therefore, pollen) exposure is far lower than historic norms. If adverse consequences are due to pollen over-exposure, we would still be net underexposed to pollen, so any increase in adverse health consequences couldn't be explained by that.

Author also presents themselves as a "horticultural epidemiologist." Worth noting that a google scholar search suggests this person is not an academic and holds no academic credentials, but he does make his income flogging a pair of books on this topic. I guess "Epidemiologist" isn't a protected title, but I usually don't see it applied to someone that doesn't actually work in epidemiology, or hold a degree in epidemiology.

droningparrot2• 7 years ago

One thing that isn't clear is how effective female trees are at removing pollen from the air. Is it possible that even with a much higher population but a more balanced sex ratio, there would still be a lower airborne pollen count?

floatingatoll4• 7 years ago

Yes, that's the core premise made by the author: If we're going to plant male plants, either we plant female plants (which have evolved to take up the maximum amount of pollen possible) or our lungs take up the pollen (which results in biological issues).

There's an inflection point where the amount of pollen left in the air by a sparse male forest equals the amount of pollen left in the air by a dense balanced-ratio forest. The article doesn't say where that inflection point is, though — when you state that inflection point as "a balanced-ratio forest can be XYZ as dense as a male-only forest with same or lower pollen counts", XYZ could be 1.1x, 20x, 5000x. Extrapolating that to urban trees, with pollen measured at human face heights, would be the holy grail of prove-or-disprove the value of this approach.

It is very likely that trees evolved to pollinate no more than is necessary to deliver the correct amount of pollen to the trees near them. I cannot find any estimates of this percentage at all, so as with XYZ above, it could be 1%, 10%, or 99%. More science is definitely required in both forest-shaped configurations and urban-shaped pockets.

droningparrot2• 7 years ago

This is such an interesting insight into how urban planning decisions can affect health.

What are the chances that airborne allergens increase rates of food allergies?

EnderViaAnsible2• 7 years ago

As I understand it, very small.

Most allergens are denatured by acid and enzymes in the stomach. Many food allergies, which typically are not the same kind of immunological reaction as seasonal allergies/allergic rhinitis, are caused more by the failure of epidermal barriers or acid attack than by mere exposure. don't become sensitized because you ate something so much as because your body allowed bits to get somewhere they are not allowed to be under any circumstances, which is why the outsized anaphylactic reaction food allergies often cause.

(...typically. In some cases it is cross reaction, where an antigen in food is too similar to some other antigen the body has previously identified as an invader. See for example the temporary meat allergy that can be caused by some Lone Star tick bites. And there are yet other causes of course...)

Seasonal allergies are usually mild because they are generally localized, peripheral, and provoked in tissues that are designed to give this response as a normal protective action.

(That is, your nose is correct to run or stuff in response to histamine release caused by pollen. Frankly, I feel some foreboding about what sequelae we will eventually discover to be caused by chronic H2 antagonist administration over decades, drugs like Claritin/Zyrtec that people are taking every day of their lives.)

So! While it is possible and some rare cross reactions have been observed (particularly in fruiting trees/eating fruits), as a general rule your seasonal allergies do not increase your food allergy risk.

Now, some people are at higher risk for both due to environmental or genetic circumstances. But there it is a prior immune dysfunction that caused both rather than one causing the other-- though it's an understandable intuition to connect them as your question does. Having one or the other makes it more likely you have both, but it one doesn't cause the other.

learc83• 7 years ago

So! While it is possible and some rare cross reactions have been observed (particularly in fruiting trees/eating fruits), as a general rule your seasonal allergies do not increase your food allergy risk.

If you're talking about oral allergy syndrome, it isn't really what I'd call rare.

Alex39173• 7 years ago

The only reason why we don't plant tons of edible fruit trees in city parks is because they would make a huge mess and attract rodents. But now that we're going to have self-driving robots that can clean up after the trees by the time they're old enough to produce fruit, there really isn't any reason why our park trees shouldn't be producing food for us.

adrianratnapala• 7 years ago

The local parks I where I lived in Germany had apple and plum trees. In spite of the fact that all the fruit came in a short time in autumn, I never saw a fully ripe fruit on the trees, let alone a rotten one fall.

Between people and birds, there was nothing left for the rats.

klyrs• 7 years ago

...there really isn't any reason why our park trees shouldn't be producing food for us.

The article does address that notion -- trees are really good at capturing pollution, and a good amount of that pollution ends up in their fruit. Which sucks. I grew up foraging urban food, and I'll still pick and eat berries and stonefruits because they're too delicious to pass up, but it seems irresponsible for governments to promote such a thing.

Alex39173• 7 years ago

The article does address that notion -- trees are really good at capturing pollution, and a good amount of that pollution ends up in their fruit.

Right, you wouldn't be able to do this with street trees for that reason, but park trees are fine. The soil just needs to be tested on a regular basis for heavy metals, but that isn't especially difficult; e.g. this has already been done for a lot of community gardens in NYC. While fruit definitely contains whatever pollution is in the environment, unlike many mushrooms it generally doesn't hyper concentrate it.

pvaldes4• 7 years ago

trees are really good at capturing pollution, and a good amount of that pollution ends up in their fruit

Must admit that this is a good reason against.

mises• 7 years ago

For what it's worth, this is quite literally a textbook example of the tragedy of the commons. Fruit will always be picked unripe, for if it is left to ripen, whoever chooses to leave it will have none.

Alex39173• 7 years ago

As long as there are is enforcement to prevent people from harvesting stuff to sell, there would always be more food than people. E.g. in NYC there are something like 30,000 acres of parks, so you could have literally hundreds of acres landscaped with edible species without meaningfully reducing other forms of public space.

pvaldes4• 7 years ago

because they would make a huge mess and attract rodents

So what? more for cats. This is just a cultural excuse. We don't need to do what is more easy or convenient for the gardener or every public space would be under a layer of green concrete now.

there really isn't any reason why our park trees shouldn't be producing food for us.

exact

aaron695• 7 years ago

The 10 people who died from the pollen storm in Melbourne was interesting.

https://www.google.com.au/amp/amp.abc.net.au/article/9907120

It also interesting because it possibly only showed up because it hit the media, but it should have been see-able before if proper stats were kept over the long term.

michaelkeenan• 7 years ago

Would it be feasible to genetically engineer trees to neither drop seeds nor release airborne pollen?

ghjjjj• 7 years ago

You don’t have to genetically engineer it. Just clone (known for millennia) a barren plant.

faissaloo• 7 years ago

Great article, horrible title

pvaldes4• 7 years ago

To use male trees in parks (when possible) is a technical choice, totally unrelated with sexism. To link all things with female opression is unhealthy and a mess leading to absurd dead ends.

Cities are full of "male symbols" in form of phallic shaped towers and square high buildings. Should we remove all of them and start building round hemispheric houses instead? Should we remove only the 50% of skyscrapers?

The term botanical sexism is unfair for garden designers (not always men) and creates a non-existent problem

robotron• 7 years ago

I think you missed the point of the article.

pvaldes4• 7 years ago

Maybe the writer should have used a better title then. Less clickbaity and annoying. That some pollens can trigger allergies when combined with diesel particles is not exactly breaking news.

Botanical Sexism Cultivates Home-Grown Allergies

Related Stories