Scientists also found that no signs of scurvy could be found on the bone samples. This indicates that lead poisoning most certainly has contributed to their death rather than scurvy.

The hermetic boxes at the house were closed with lead and it is very likely that the lead poisoned the food. Lead poisoning affects the nervous system and causes mental and physical weakness, which also correspond to the symptoms described by the trappers in their journal diaries.

Source : Svalbard Science Forum