The tonnage of easily adsorbed lead oxides used in paints that powdered off and became road & houshold dust dewarfs the tonage put into petrol by many orders of magnitude
But sueing paint companies is not as sexy as pilloring fuel companies
If you don't look for things you never find them
The bulk of the environmental free lead has come from paint and it is still being used in a lot of paints because there is no viable substitute for the UV protection it gives to large steel & cast iron structures like bridges & gasometers .
It is very cheap & easy to take a dust sample or air sample and do a strait chemical lead content
And of course because lead is very heavy the weight percentages always look massive.
Doing molecular lead determinatins is very expensive so it does not get done very often but that is the only way to determine where the lead actually came from but if you have a predetermined culprit then you do not want to know that .
Rignt now lead is a major addition to car tyres so road side dust will always show high lead levels and the ego inflaters will naturally attribute it all to those nasty petrol companies because they are all evil and it is fashionable to blame them for everything .
A sizeable amount of the lead found in sea water can be attributed to climate change as the increased amount of sulphur & co2 in the atmosphere since the industrial revolution has drastically incrreased the occurance of carbonic acid and sulhhuric acid both of which attack lead roofing products .
Nitrates in the atmosphere attack the bare lead when the above acids have removed the protective oxides from the surface .
Nothing is as simple as You tube likes to make it out .
Strait lead metal can not be adsorbed by animals
The standard experiment was to get undergratuate to swallowsome lead shot then when recovered wash & dry it
The results were always the same the dry weight in was the same as the dry weight out down to the 5th decimal place
Lead oxides are a different matter they are easily adsorbed by a human body
Tetra ethyl lead prior to combustion is easly adsorbed both in the digestive tract and through the skin, this includes breathing it in but it has the be highly atomised first so you have to be breathing in a petrol mist .
Post combustion it is very hard to be adsorbed untill prolonged exposure to UV rays starts to break it down, basic high school entropy .
Remember just becaue the road is wet that does not mean it has been raining .
Now it has been 40ish years since I was involved in biological monitoring of lead in the foundry workers plus environmental monitoring of lead in the surrounding ares, including the tidal canal next to the foundry and the same for the 6 battery
plants we ran .
There is a lot more to lead than just petrol
Medically it is really only a problem in developing children and no arguement , it can be a very big problen to developing brains .
Adults usually suffer nothing worse than annemia as the lead bonds to the hemoglobin preventing it from taking up oxygen .
And that reverses with reduced exposure as the kidneys have no problem removing it from most people.
The two screening tests were hemoglobins & lead in urine
So if it is in your urine ( or stools ) then the body is purging it from your system
The stuff you really need to worry about is the stuff that accumulates like mercury and even nice safe zinc .
All metal oxides, sulfides & chlorides are posonious it is just a matter of the degree of the toxicity