import pandas as pd
import numpy as np

from io import StringIO
source = StringIO("drop_id,point,kg\n001,NA,12\n002,north,\n")
table = pd.read_csv(source, dtype={"drop_id":"string", "point":"string", "kg":"Float64"}, keep_default_na=False, na_values={"kg":[""]})
print(table["drop_id"].tolist())
print(table["point"].tolist())
print(table["kg"].isna().tolist())