Who were the first europeans to explore north america?
portuguese
spanish
vikings
french

The first Europeans to explore North america were the vikings.

Explanation:

at least the first for whom there is solid evidence -- were Norse, traveling west from Greenland, where Erik the Red had founded a settlement around the year 985. In 1001 his son Leif Erikson is thought to have explored the northeast coast of what is now Canada and established a colony near what is now Lanse Aux Meadows, Newfoundland. Erikson and settlers spent at least one winter there before abandoning the settlement for unknown reasons.

explanation:

allergens: overstimulate the nerve system

neurotics: attack nerve cells

mutagens: damage or otherwise alter dna sequence

generators: cause defects during growth and development  

carcinogens: cause unchecked cell growth

i hope you get the idea according to me these are the effects that happened.