Safe disposal of ricin, Ricinus Communis, seeds

Hello!
We've allowed two ricin plants to flourish in our near-vertical gabion cage garden, mainly because they shade the terraces during our harsh winter. (Harsh in a different way - our Mexican mountaintop winter is dry with piercing sunshine in the day and cold nights). They're about 4 m tall and their branches spread out to an approx. 5 m diameter. Now we've learned that the seeds can be super toxic if chewed. Nobody in our household has shown any indication of picking and chewing the seeds so far, but who knows, visiting children etc. And the plants are ridiculously prolific, sprouting new clusters of seeds constantly.
Earlier we've cut down the seed clusters and left them in a bucket with lid to grow mold and, we hoped, eventually turn into useful compost because it's a lot of biomass. But we may need to get more proactive and maybe dispose of both the trees.
US websites seem to propose cutting down the entire plant in full hazmat gear, boiling the plants "in a large pot" (this makes me think the person who wrote the articles have no clue, because we're talking medium tree-sized plants), burying the soup three feet deep and double/bagging then disposing of the hazmat suit, the pot and the tools at your local hazardous waste treatment centre. HA!
Do you permies have more common-sense suggestions?
We live in a dense urban area so "burning the plants on a windless day well away from people and animals" is not an option.  
Apparently the ricin dissipates once the seeds germinate and sprout, so maybe letting them grow for a week and then murdering the seedlings would work?
Our roof terrace gets extremely hot with the abovementioned sun, might the seeds die broil and stop being toxic if left in black bags out there?

Appreciate ideas!
(P.S. getting the plants to stay dead will be another issue, they are ridiculously determined to live and sprout new leaves constantly in response to pruning.)

I've got that stuff all over my property. I grow it for mulch.

First,  to get rid of the plant: just dig down a few inches below the surface to chop it off. That should do it. If it sprouts back just chop it off again. After a couple times of that it definitely shouldn't have any energy left.

For the seeds,  can you just put them on the trash? If not,  just put a little soil in the bucket and let them sprout. Then you can compost the sprouts.

Lemme know how it goes!

Or another option: roast the seeds and press the oil out. It makes a real lovely lotion.

Nathanael Szobody wrote:Or another option: roast the seeds and press the oil out. It makes a real lovely lotion.

I have read that the lotion is a great moisturizer and pain reliever.

seriously, i wouldn't worry about it. I know I differ from other gardeners I respect in the US, but where I live it is a common weed and I can't walk ten meters without falling over one. I have never heard of anyone getting poisoned off them.
In fact I just macheted my big one in my backyard, i make "swamp tea" out of it to spray my young plants with as a foliar feed/bug repellant. Otherwise, I do chop and drop. I wouldn't chew on the leaves, and while I hear you about random kids coming into your yarde and maybe chomping on them I think oleander and datura are probably much worse and way more common....
My busband grew up slingshotting the seeds at his friends, a pasttime we have also picked up. choppíng off the immature seed bundles seems like a reasonable way of dealing with them if you're uncomfortable with the seeds (and they do sprout up like crazy-- if you have poor soil, they are probably the most reliable "big shade quick" plant youre going to get in a hot place).

From Brazil, where the oil from these seeds was the most common way to rustproof your car chassis and farm equipment before the advent of petrochemicals! with the added plus of making your skin and nails very happy, as Nathanael notes.

it's only really dangerous if someone gets it into their umbrella

Brilliant, friendly permies. Thanks for the responses.
We also grew them for mulch (and shade), although rust-proofing trucks also sounds like a brilliant use.
I'll stop worrying and maybe try letting the collected seeds sprout with a bit of soil in the same bucket they're in now.
Happy December!

Most cities I've lived in, have a system in place for disposing of harmful plants.  Depending on the plant and the risk to children, you can drop it off at the location, or they will dress up in space suits and remove it for free.

Might be worth asking at the place where you take old lightbulbs and batteries to be recycled.