Edit: This also helps others who are in accidents, car wrecks, have Cancer, etc. Yes, we pass on the PFAS to others, but the immediate need for blood is more urgent than the potential long term impacts of PFAS.
I used to donate blood regularly but now that I'm in Japan they require me to be decently fluent in Japanese to "understand" the risks, despite having done it a bunch of times in other countries (and other medical procedures not requiring Japanese knowledge).
> Surely there's a better way to filter out risky blood
It's simple Bayesian probability. Blood tests have a relatively high error rate. Hep-B tests have a 6-12% false negative rate early in the disease, and Hep-C is 3-6% even later in the course of the disease. That's considered a "very low" false-negative rate for a blood test.
In Bayesian terms, blood tests don’t “screen” for a disease. They reduce the odds ratio of contaminated blood by a factor of 10 or so. But the ultimate odds still depends heavily on the prior odds—the prevalence of the disease in the donor population: https://en.wikipedia.org/wiki/Prior_probability. Even with testing, you can reduce the risk of contaminated blood by drawing blood from a pool of donors that has lower prevalence rate of diseases.
MSM is one of the highest risk activities you can do for bloodborne diseases. If this is discriminatory, life is discriminatory. Life is not fair, and there is nothing any artificially constructed social system will ever do to force mother nature's hands to make life fair. I fully support the rights of people to love and be in relationships with whoever they wish, but that doesn't mean you have the right to contaminate the blood supply due to the inherently high risk of your day-to-day life.
I have never been able to donate blood because of my travels due to their locations and frequencies. I am not going to give up travel to donate blood. MSM is a much higher risk activity than travel, and yet I am also excluded due to my lifestyle risk. It's not fair, but it is reasonable.
With travel, I understand that there is a higher risk of lots of diseases, and testing against all possible infectious diseases is not feasible. Drug use is also obviously disqualifying. But why would you care about someone's sexual behavior? The blood must be tested for common drugs and common blood borne diseases regardless, and it's perfectly possible to engage in sexually risky behaviors and not have any venereal disease (unlike with drug use, where it implicitly means you will have levels of those drugs in your blood), just like it's possible to be very careful with your sexual behavior and still get a disease.
Note: for tattoos, I have no idea if the problem is also related to venereal diseases, or if there is any problem from contamination with the tattoo ink itself, and I don't care enough about this subject to look it up.
> But why would you care about someone's sexual behavior? The blood must be tested for common drugs and common blood borne diseases regardless, and it's perfectly possible to engage in sexually risky behaviors and not have any venereal disease
Men who have sex with men are something like 50-100x more likely than the general population to acquire HIV. HIV tests do not have a 0% false positive. They will not catch all very recent infections. The rationale for excluding them until recently is that it’s defense in depth and it doesn’t hurt the blood supply much because they only make up about 2-3% of the population.
The current rule is that MSM don’t face a blanket ban, but if you’ve had anal sex in the last 3 months you have to wait because anal sex is inherently more likely to transmit HIV and the tests may not catch a very new infection. Other diseases like Hepatitis have a similar issue.
The answer to all of that is mainly hepatitis C, that can have a window detection of 6 months, even more.
And yes, you can be very careful and get a disease. But they are playing statistics here: over 60% of injected drug users have Hep-C, that means a lot of prostitutes. They won't and shouldn't trust anyone who say "hey, I had unsafe sex against all advice, but was very careful with the tattoo in a dark cellar and the heroin party, pinky promise".
For tattoos, if the artist isn't using a brand new set of needles for you, you risk bloodborne disease transmission, with hepatitis B being a particular danger.
Unfortunately tests are not 100% accurate and there's a window between when the pathogen is present and when it's detectible. Add in that many viruses aren't directly detectable, the tests look for antibodies to the virus.
This is why they usually ask if you've had a new sexual partner in the past 3 or 4 months. This is the window period for detecting some STDs and other diseases.
All of these things can mostly be tested. When I donated regularly in the UK after being in the southern US, they screen me for west nile virus but still take my blood and use it.
Granted it’s shorter, but there are longer wait periods depending on the country. It’s defense in depth because false negatives happen and some viruses take time to show up on tests.
"If you spent over 4 weeks in primitive or rural accommodation you have to wait for 4 months after your return before giving blood. However, if you were travelling and staying in places which are modern and clean, such as typical tourist areas, please wait 4 weeks from your return due to Tropical Virus risk which includes Chik V, Dengue or Zika risk providing you do not have symptoms of these."
“ If you visited the rural areas of the states - Chiapas, Chihuahua, Durango, Sinaloa districts, Quintana Roo, you need to wait for 4 months after your return to the UK before giving blood. ”
The US rules also aren’t 4 years (not sure why someone told the OP that). It’s 3 years after undergoing malaria treatment. And 3 months after visiting a malaria prone area.
The bigger worry isn't really false negatives, modern PCR based testing is incredibly good. There is always risk but it's frankly extremely low. The bigger issue is that blood is pooled before testing to make that powerful testing economical. If you increase the rate at which you get (also possibly false) positives you risk having to throw out whole batches of pooled donations.
No, it's not though. That's true for antibody tests commonly used for individuals because it's cheap. The window period for nucleic acid testing that is used for blood supply is very short. This test is similar to what's used to confirm a positive antibody test, but isn't used for individual testing because it is too expensive. Hence the pooling.
Tests cost money. They have blood enough to allow them to discriminate. If they were lacking, they will be less picky: in a catastrophic event they call for blood donors and they rely on tests, risking a detection window.
But under normal conditions, letting only the best candidates donate is the most efficient way.
Generally, because they're discriminatory. It's like how racial profiling in law enforcement can be a heuristic that can work. Though, in the case of blood donations, it seems that tests aren't accurate enough to be able to rely solely on them. Also, being discriminated against on being able to donate blood is not as big of a deal. Though in some places with public health systems, stuff like getting a surgery may somewhat depend on you and family/friends donating a certain amount of blood.
should test? As in test the blood? Or test the hypothesis?
if the latter I'm not sure it's enough of a stretch to say unprotected, hi-risk, promiscuity is a risk factor for blood borne illness like HIV? (Such that we need to research it separately)
We do test the blood, but they also do coarse grained screenings like this to avoid some level of waste on intake. It's like having client and server side validation.
Let's say a year ago, you walked across a bridge in Mexico for five minutes to see if it's true that Mexico has a yellowish haze like in the movies. Oh, it doesn't. Then you walked back to Texas.
A year later, you go to a blood donation center and they ask you: "Did you go to Mexico in the last N years?"
If you say "Yes", you are banned for four years. If you say "No", you donate liters of blood over the next four years.
If you were in this exact situation, how would you weight which answer is better?
I understand where you're coming from. But on the off chance something unrelated were to go wrong with the blood down the line, it could be shown that a false answer was knowingly given. You have to weigh this risk against keeping "the privilege to give blood". I guess it depends on your values and risk tolerance.
I'm not sure there are any regulations around opting to do that in the US. Do you have a phlebotomist friend? If so, they might do it for you, but it can be risky and they might not want to take the risk, get sued, etc.
It is an interesting question. Are there companies that draw and discard?
What makes PFAS so difficult to deal with is the fact that they are particularly inert. Teflon works because it doesn't react with almost anything. I've seen some studies about using UV light to kill off PFAS, but that's not going to be desirable when you want those red blood cells to also survive.
I think people getting blood usually have lost a bunch of their own first. And blood isn't usually given just for fun, it's to save their lives, i.e. PFAS isn't a huge concern at that point.
I'd assume donated blood matches the average level that people already have in them, so not sure it really matters. But if you donated regularly enough, you could be donating blood that has lower than average levels!
PFAS doesn't immediately harm you like missing a few pints of blood does.
And it's not like you're concentrating higher levels of PFAS into the recipient, they likely have the same average blood concentration levels as the donor does since we're all equally exposed to the same sources.
https://jamanetwork.com/journals/jamanetworkopen/fullarticle...
Edit: This also helps others who are in accidents, car wrecks, have Cancer, etc. Yes, we pass on the PFAS to others, but the immediate need for blood is more urgent than the potential long term impacts of PFAS.