GSTM1 and anemia (phenotype): The prevalence of mild anemia (100 g/L ≤ Hb < 110 g/L) was 30.0%; the prevalence of moderate anemia (70 g/L ≤ Hb < 100 g/L) was 23.5%; and the prevalence of severe anemia (Hb < 70 g/L) was less than 1%.