Generally, workers' compensation and recoveries against an asbestos manufacturer are not subject to income tax.
Social Security benefits are partially taxable, depending on your income for the year you receive them. Union pension benefits are taxable if you didn't pay the insurance premiums that bought them; they are tax-free if you did.
If you lose Social Security benefits because you also got workers' compensation, the amount of those workers' compensation benefits is taxable as Social Security even though workers' compensation is not taxable.
Understand that tax laws change over time and you should consult an attorney or a tax professional to verify your tax requirements.