I don't know anything about silicone poisoning and I don't want to suggest that it's not a problem with Mirena; I have no idea one way or another. But a lot of the symptoms that people here associate with silicone poisoning are also symptoms of hormone imbalances (especially low progesterone). I saw this website arguing that it's BECAUSE the hormones are localized to the uterus that's the problem—our bodies get confused and stop producing progesterone in sufficient amounts. But the entire body (including the nervous system!) needs progesterone, not just the reproductive organs, so when there isn't enough of it, bad things ensue. (Because progesterone is important for calming the nervous system, it gets overstimulated when there isn't enough progesterone, leading to things like heart palpitations, elevated heart rate and blood pressure, anxiety, and peripheral neuropathy--all things that I experienced, and that I've seen on this forum over and over and over.) Since I've had the Mirena out I've been tracking my fertility signs with the Fertility Awareness Method (not trying to get pregnant--actually trying to avoid it, and also trying to better understand what's going on with my hormones), and recurrences of my symptoms (which are almost but not completely gone) are definitely tied to hormonal shifts, which at this point (8 weeks post removal) are not back to normal.
"It seems that Mirena is a common factor in the majority of the cases I’m seeing. The possible reason is that, although Mirena provides progestins to the uterus, its hormones do not reach progesterone receptors in other areas of the body, for example the breasts, adipose tissue or brain, where progesterone normally will have an effect. While oral contraceptives act by preventing ovulation (some women don’t even menstruate while using the IUD), which in turn prevents the secretion of natural progesterone from the corpus luteum (formed in the ovary after ovulation), many of them also supply a dose of synthetic progesterone. Since the Mirena IUD only secretes progesterone to local tissues and therefore only acts at local receptors, it may be turning off the body’s ability to secrete natural progesterone—negative feedback loops might instruct the pituitary gland and the adrenal glands to stop making the body’s own progesterone."