That is, oral intake of lead with oral intake of garlic, means maybe you shit out more lead with the garlic chelation agent. But lots of garlic will do nothing for water you drink later in the day, or the air passing into your lungs.
There may be some additional anti-oxidant activity. Anti-oxidants are good for you across the board. Have at them.
As to a safe blood lead level: depending on your local public health department, 5 mcg/dL will or should prompt public health action. <5mcg will usually prompt a doctor to start trying to figure out where you're exposed, and cut that exposure out. >5mcg turns into a little bit of a grey area depending on where you are, and by 10mcg your kid is getting chelation therapy. These numbers are built around children, not adults, because they're far more susceptible to the adverse effects of lead exposure.
That said, we have not identified any safe lead level - every level that has been tested has been shown to be associated with some sort of negative cognitive developmental impact (Lanphear 2000). I feel comfortable saying the safe level is "0", but that's not medical consensus, that's just my opinion.
There are a number of relevant factors including length of exposures (acute or chronic poisoning) and form of metal (organic, inorganic, metallic - for mercury at least).
By far the best source I found on the topic is Andrew Cutler, a chemistry PhD from Princeton who was mercury poisoned himself and created an effective and safe protocol for removal. He has a strong background in kinetics, pharmacokinetics, and biochemistry in general, and recognized that the standard toxicological protocols for heavy metal treatment were very dangerous (e.g. infrequent high dose IV administrations of DMPS/DMSA) , especially for cases of chronic poisoning.
According to Cutler, protocols such as the one you linked are very dangerous as they don't administer the chelating agent according to its metabolic half-life in the body (the half-lives of the chelating agents in cilantro and chlorella are unknown). As a result blood levels of the chelating agent and the metals fluctuate greatly. This can mobilize previously sequestered metals, but not provide the body enough time to properly eliminate them, which results in "re-poisoning" events. And when a large amount fat-loving free metals are released by the chelating agents within a short period of time, they often enter the central nervous system, settle there and exacerbate neurological symptoms.
I have no background in chemistry, so that's my summary of what I've read. But I highly recommend his book [1] which focuses mostly on mercury, but he covers lead as well. There are a few interviews with him around the web as well [2]. Also happy to provide more info and sources as I have two of his books and they both cite a wide array of sources.
Scopus, which seems to be run by Elsevier, lists some abstracts and letters here (I have no idea how extensive this is) [1]
[1] https://www.scopus.com/authid/detail.uri?authorId=7103370042
I guess chelation/elimination does work if the WHO writes about it.
AFAIK lead is also stored in bones and probably within body tissues, so this might take a while.
And is there any merit in "chelation" therapies, as advocated on health websites, like this one, [1]?
[1] https://www.livestrong.com/article/199912-what-natural-herbs...