Nearly every parts on computer boards have very little, if any, toxic chemical. Usually the lead (in solder mostly) is the worst of all and it's easily dealt with.
Actually, tantalum capacitors can cause lung problems if the tantalum is crushed or burned and then inhaled. Fortunately tantalum caps are becoming rarer.
Ceramic IC packages and some types of heat sinks contain berylium, as do high-power RF transistors. Berylium causes CBD (Chronic Berylium Disease) and is a known carcinogen, so it's best to avoid cutting or grinding on those types of devices without plenty of dust protection.
