Association between Blood Donation and Malignant and Benign Tumour Risk: A Population-Based Study of 3.4 Million Participants in China

Table 1

Basic demographic characteristics of blood donors and nonblood donors in the study.

Participants	Nonblood donors	Donors
Total (n, %)	1625599	1625599
Gender
Male	968823	968823
Female	656776	656776
Age, years	35 (28–44)	35 (28–44)
Region
North Shaanxi (n, %)	86540	86540
Middle Shaanxi (n, %)	1148936	1148936
South Shaanxi (n, %)	390123	390123
Education
Junior high and below	913711	897254
Senior high	443576	419499
University and above	65779	108228
Unknown	202533	200618
Occupation
Student	54331	90144
Worker	178022	227108
Peasant	992334	856698
Self-employed	372667	431531
Unknown	28245	20118
Marriage
Single	422656	433382
Married	1079398	1071802
Divorced	11379	19911
Unknown	112166	100504
Days between blood donations (if participants with more than one donation)	—	1772 (672–3001)