The professor who warned me about fern toxins was actually a fern expert, both fossil (Paleobotany) and living. Her vast knowledge of ferns gave her words puissance.
naf, older leaves will brown, which is normal. If younger leaves are browning, it could be due to mites, low humidity, excess sun, mineral buildup in the pot or soil, or lack of nutrition/fertilizer. Fortunately, gingers are pretty tough.
