Friends of the Earth claims that due to the "dangerous and unregulated" tin mining on Bangka, in 2011 an "average of one miner a week died in an accident." The activists also claim coral and sea life is threatened due to silt from tin mining, which they claim is "killing coral reefs and seagrass eaten by turtles, driving away fish and ruining fishermen's livelihoods." In addition soil has become acidic after the destruction of forests for tin mining, making conditions difficult for farmers.
The average 650-gram iPad contains 1.3 grams of tin (used in soldering). While it may seem unfair that Friends of the Earth has only targeted Apple (when everyone who makes electronics uses tin), if you want your activism to be noticed and your message to reach the widest possible audience, you picket the company that gets the most press and that also happens to be the largest consumer technology company on the planet (both Apple).
Friends of the Earth has written to Apple CEO Tim Cook regarding the issue, but as of yet, no return correspondence has been publicized.
Image from Rachel Kennerley Twitter feed.