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• Arsenic levels in water in the Quebrada Camarones region of Chile's Atacama desert per litre (25 February, p 10).

• The ways in which the masked birch caterpillar signals include drumming with its mandibles and dragging its anal “oars” (4 March, p 19).

• Nerve agent VX would better be described as the most toxic synthetic chemical known (4 March, p 6).

• Larry Weiss is chief medical officer of US start-up AOBiome (4 March, p 22).