In a recent post about trading stuff for money, I mentioned:

Europe had a [blood plasma] shortage of around 38%, which it met by importing plasma from paid donors in the United States, where blood products account for 2% of all exports by value.

The internet’s reaction was: “TWO PERCENT?” “TWO PERCENT OF U.S. EXPORTS ARE BLOOD!?”

Well, I took that 2% number from a 2024 article in the Economist:

Last year American blood-product exports accounted for 1.8% of the country’s total goods exports, up from just 0.5% a decade ago—and were worth $37bn. That makes blood the country’s ninth-largest goods export, ahead of coal and gold. All told, America now supplies 70% or so of the plasma used to make medicine.

I figured the Economist was trustworthy on matters of economics. But note:

1. That 1.8% number is for blood products, not just blood.
2. It’s a percentage of goods exported, excluding services.
3. It’s wrong.

The article doesn’t explain how they arrived at 1.8%. And since the Economist speaks in the voice of God (without bylines), I can’t corner and harass the actual journalist. I’d have liked to reverse-engineer their calculations, but this was impossible since the world hasn’t yet caught on that they should always show lots of digits.

So what’s the right number? In 2023, total US goods exports were $2,045 billion, almost exactly ⅔ of all exports, including services.

How much of that involves blood? Well, the government keeps statistics on trade based on an insanely detailed classification scheme. All goods get some number. For example, dirigibles fall under HTS 8801.90.0000:

Leg warmers fall under HTS 6406.99.1530:

So what about blood? Well, HTS 3002 is the category for:

Human blood; animal blood prepared for therapeutic, prophylactic or diagnostic uses; antisera and other blood fractions and modified immunological products, whether or not obtained by means of biotechnological processes; vaccines, toxins, cultures of micro-organisms (excluding yeasts) and similar products:

The total exports in this category in 2023 were 41.977 billion, or 2.05% of all goods exports. But that category includes many products that don’t require human blood such as most vaccines.

To get the actual data, you need to go through a website maintained by the US Trade Commission. This website has good and bad aspects. On the one hand, it’s slow and clunky and confusing and often randomly fails to deliver any results. On the other hand, when you re-submit, it clears your query and then blocks you for submitting too many requests, which is nice.

But after a lot of tearing of hair, I got what seems to be the most detailed breakdown of that category available. There are some finer subcategories in the taxonomy, but they don’t seem to have any data.

So let’s go through those categories. To start, here are some that would seem to almost always contain human blood:

Next, there are several categories that would seem to essentially never contain human blood:

Finally, there are categories that include some products that might contain human blood:

The biggest contributor here is IMMUNOLOGICAL PRODUCTS (be they MIXED or UNMIXED, PUT UP or NOT PUT UP). The largest fraction of these is probably antibodies.

Antibodies are sometimes made from human blood. You may remember that in 2020, some organizations collected human blood from people who’d recovered from Covid to make antibodies. But it’s important to stress that this is quite rare. Human blood, after all, is expensive. So—because capitalism—whenever possible animals are used instead, often rabbits, goats, sheep, or humanized mice.

I can’t find any hard statistics on this. But I know several people who work in this industry. So I asked them to just guess what fraction might include human blood. Biologists don’t like numbers, so this took a lot of pleading, but my best estimate is 8%.

When looking at similar data a few years ago, Market Design suggested that that immunoglobulin products might also fall under this category. But as far as I can tell this is not true. I looked up the tariff codes for a few immunoglobulin products, and they all seem to fall under 3002.90 (“HUMAN BLOOD; ANIMAL BLOOD PREPARED FOR THERAPEUTIC, PROPHYLATIC OR DIAGNOSTIC USES; ANTISERA AND OTHER BLOOD FRACTIONS, ETC. NESOI”)

What about vaccines or cell therapy products? These almost never contain human blood. But they are sometimes made by growing human cell lines, and sometimes those cell lines require human blood serum to grow. More pleading with the biologists produced a guess that this is true for 5% of vaccines and 80% of cell therapies.

Aside: Even if they do require blood serum, it’s somewhat debatable if they should count as “blood products”. How far down the supply chain does that classification apply? If I make cars, and one of my employees gets injured and needs a blood transfusion, are my cars now “blood products”?

Anyway, here’s my best guess for the percentage of products in this middle category that use human blood:

So 0.5298% of goods exports almost certainly use blood, and my best guess is that another 0.1569% of exports also include blood, for a total of 0.6867%.

Obviously, this is a rough cut. But I couldn’t find any other source that shows their work in any detail, so I hoped that by publishing this I could at least prod Cunningham’s law into action. Sorry for all the numbers.