They said eating papaya or taking ascorbic acid is dangerous during pregnancy because it leads to natural abortion..is this true?

Never heard that one: I don't think this is a real thing. Moderate consumption of fruit like papaya and intake of Ascorbic Acid (vitamin c) in non excessive quantities shouldn't be an issue. I would be more concerned with taking in high mercury containing fish since you are on a pacific island.

Labor: Unripe vs ripened papaya. The latex in unripe or partially ripe papaya contains papain which could potentially stimulate uterine contractions (like Prostaglandins). Massive amounts of vitamin C have been used to stimulate labor. Remember that most natural methods can harm both the mother and fetus.