Both these statements are misleading. This would be a highly exceptional number of seeds and an advert claiming that each plant produces 150,000 seeds has been banned by the Advertising Standards Authority.
see Ragwort seed production
Also the seed germination figure is essentially meaningless.
see Ragwort seed germination
The website also irresponsibly frightens people by repeating the well-known human poisoning story. " Ragwort is also harmful to humans. It can enter the bloodstream through the skin: protective clothing MUST be worn when handling the plant. "
Ragwort is, the research tells, us not a poison risk to humans that is really worth worying about and the plant and really has no serious risk to people. The skin absorbtion poisoning idea just doesn't seem to stand up to investigation.
This website contains several articles on this. Ragwort poisoning in Humans for a quite short explanation and Ragwort Humans for a slightly longer one. This is a really common myth that leads many of problems for people so a simple non-technical explanation of this is available here Ragwort poisoning humans .
Perhaps the best key to the attitude of Surrey Council is given by the original statement made on their website."Hopefully it is not too late to help in the campaign against this insidious killer." It may explain why they repeat scarey myths. They are campaigning against ragwort. Notably that statement has been removed from the website but the other misleading statements have not.