Table 2.

Mendelian randomization (MR) analysis of air pollution (particulate matter, nitrogen dioxide and nitrogen oxides, exposure) with primary liver cancer outcome in European population.

Exposures	Methods	Beta	p	Number of SNPs	R 2	F	P (Cochran’s Q heterogeneity test)	P (MR-Egger intercept test)	P (MR-PRESSO global test)
PM2.5	IVW	−0.014	0.993	8	0.069%	292.604	0.078	0.411	0.326	Weighted median	0.285	0.846	MR-Egger	1.315	0.596	Simple mode	0.191	0.955	Weighted mode	0.435	0.770
	PM2.5–10	IVW	0.313							0.833	23	0.130%	534.813	0.057	0.720	0.081	Weighted median	1.250	0.422	MR-Egger	0.879	0.691	Simple mode	−1.000	0.776	Weighted mode	0.990	0.522
		PM10	IVW							−1.698							0.257	22	0.159%	810.361	0.593	0.609	0.578	Weighted median	−3.305	0.107	MR-Egger	0.173	0.965	Simple mode	−4.763	0.182	Weighted mode	−4.506	0.171
			Nitrogen dioxide							IVW							6.478							0.215	4	0.032%	158.579	0.079	0.888	0.219	Weighted median	3.917	0.458	MR-Egger	−3.456	0.966	Simple mode	2.864	0.641	Weighted mode	3.270	0.594
										Nitrogen oxides							IVW							3.337							0.614	8	0.060%	283.730	0.204	0.198	0.271	Weighted median	1.283	0.720	MR-Egger	28.909	0.180	Simple mode	4.573	0.786	Weighted mode	4.237	0.730

PM, Particulate matter; MR, Mendelian randomization; IVW, Inverse variance weighted; SNPs, Single nucleotide polymorphisms.

R²: the percentage of iron status variability explained by each SNP; F statistic to assess the presence of a weak instrumental variable bias.