By Sony Salzman
BU News Service

At a Red Cross facility in downtown Boston, centrifuge machines churn in a low hum while nurses tend to paperwork and volunteers fight nausea.

Volunteers are here for more than just a typical blood donation. A needle in each donor’s left arm removes blood, which is then stripped of platelets and plasma and returned to the body through a needle in the right arm. The plasma will later be used later to help patients with hemophilia, compromised immune systems and other disorders. But for the time being, it collected into a bag that hangs like an IV drip over the donor’s left shoulder.

The whole assembly looks like so:

On this particular autumn day at the Red Cross Donation Center, four volunteers sit along the south wall as their plasma slowly drips into respective plastic bags hanging over the left shoulder. Each person’s plasma is a thin yellow color. That is, every person except one: a young woman in the last chair on the right, whose plasma is a mysterious Hulk-green color.

Typical plasma: 

Hulk plasma: 

Is there something wrong with this woman? Is she an alien? Is she part-squid? Is she maybe suffering from some kind of weird bacterial infection?

It turns out she’s just on birth control. Oral contraceptive pills create a harmless chemical reaction with certain proteins in plasma that turn the yellow liquid to green. Moreover, the green plasma is completely normal. Even plasma that looks orange or “milky,” instead of the typical yellow color is safe to donate.

Plasma is the watery part of every person’s blood, and makes up about half the total volume of blood. Swimming around in plasma are proteins, blood clotting factors and hormones. Plasma surrounds red blood cells, helping transport waste, nutrients and immune cells in case of infections.

This woman’s plasma is actually green because of increased levels of copper – just like the copper Statue of Liberty is green. Inside her body, the birth control hormones trick her liver into producing more of an enzyme called Ceruloplasmin (the same thing happens when women are actually pregnant). This enzyme has six copper atoms in its chemical structure. The boosted presence of this enzyme is enough to turn the plasma green.

There are a variety of chemical reactions that can have a benign effect on blood plasma. For example, if you eat a ton of carrots (and therefore a lot of vitamin A), your plasma will look kind of like SunnyD. If you eat a really high-fat diet, your plasma is going to look like butternut squash soup.

However, even though green or milky plasma is totally safe to donate, technicians are trained to watch out for more nefarious variations in plasma. For example, little particles inside the plasma baggie might indicate a blood-borne infection, and these donations have to be tossed in the garbage.

But despite the suspicious-looking green plasma bag in a room full of yellow bags, this woman’s donation is A-OK. The grateful recipients care much more about the generosity of this woman’s donation than the color of her plasma.