Nitrate-nitrite-nitrosamines exposure and the risk of type 1 diabetes: A review of current data

Table 1 Summary of results from ecological, case-control and cohort studies of mean nitrate levels from drinking water in relation to incidence of type 1 diabetes

Ref.	Country	Exposure levels (mg/L)	Findings
Muntoni et al[34]	Italy	≤ 2.5	OR = 1.0
		2.5-4.0	OR = 0.6 (95%CI: 0.4-1.0)
		4.0-6.5	OR = 0.5 (95%CI: 0.3-0.7)
		6.5-28.9	OR = 0.6 (95%CI: 0.4-1.0)
			P = 0.027
Parslow et al[28]	United Kingdom	1.5-3.2	OR = 1.0
		3.2-14.9	OR = 1.11 (95%CI: 0.98-1.26)
		14.9-40.0	OR = 1.27 (95%CI: 1.09-1.48)
Winkler et al[30]	Germany	< 9.58	OR = 1.0
		≥ 9.58	OR = 0.9 (95%CI: 0.6-1.3)
Zhao et al[35]	England	1-3.6	SIR = 1.11 (95%CI: 0.96-1.29)
		3.6-7.8	SIR = 0.99 (95%CI: 0.85-1.15)
		7.8-16.6	SIR = 0.90 (95%CI: 0.77-1.05)
			χ2 = 3.8, P = 0.048
van Maanen et al[31]	The Netherland	< 10	SIR = 0.99 (95%CI: 0.93-1.06)
		10-25	SIR = 0.99 (95%CI: 0.84-1.14)
		≥ 25	SIR = 1.45 (95%CI: 0.85-2.07)
		0.2-2.1	SIR = 1.02 (95%CI: 0.92-1.13)
		2.1-6.4	SIR = 0.95 (95%CI: 0.85-1.06)
		6.4-41.2	SIR = 1.02 (95%CI: 0.92-1.12)
Casu et al[32]	Italy	Approximately 10	Simple correlation = -0.17, P = NS
Samuelsson et al[33]	Sweden	0-80	OR = 1.32 (95%CI: 1.06-1.64), P = 0.013
Moltchanova et al[36]	Finland	0.2-6.64	Posterior mean unit effect = 0.0026 (95%CI: -0.0093-0.0138)
Kostraba et al[29]	United States	0-8.2	Correlation = 0.23, P = 0.07

OR: Odds ratio; SIR: Standardized incidence ratio; NS: No significance.

Table 2 Summary of results from ecological, case-control and cohort studies of mean nitrite levels from drinking water in relation to incidence of type 1 diabetes

Ref.	Country	Exposure levels (mg/L)	Findings
Winkler et al[30]	Germany	< 0.009	OR for β-cell autoimmunity = 1.0
		≥ 0.009	OR for β-cell autoimmunity = 0.6 (95%CI: 0.4-1.0), P = 0.07
		< 0.009	OR for type 1 diabetes = 1.0
		≥ 0.009	OR for type 1 diabetes = 1.5 (95%CI: 0.6-3.5), P = 0.074
Samuelsson et al[33]	Sweden	0.02-0.16	OR = 0.36 (95%CI: 0.06-2.03), P = 0.25

OR: Odds ratio.