Table 1.

Evaluation of the epidemiological evidence of the association between cause of death and environmental exposures.

Sufficient (S) Sufficient to infer the presence of a causal association	(i) the Sufficient evaluation relies on one or more primary sources or on the data they provide for such evaluation
	or
	(ii) Quantitative meta-analyses provide data for an evaluation classifiable as Sufficient
Limited (L) Limited but not sufficient to infer the presence of a causal association	(i) one or more primary sources/quantitative meta-analyses/reviews/multicentric studies/two or more single studies report the existence of a causal association but they do not express a Sufficient evaluation, or they do not provide data for such evaluation
Inadequate (I) Inadequate to infer the presence or the absence of a causal association	(i) some primary sources study the causal association but they disagree about the evaluation (conflicting evidence)
	or
	(ii) some quantitative meta-analyses/reviews/multicentric studies/two or more single studies analyze the association but they disagree about the evaluation (conflicting evidence)
	or
	(iii) some primary sources/quantitative meta-analyses/reviews/multicentric studies/two or more single studies analyze the causal association but none of them reports its existence
	or
	(iv) the available studies are not consistent (conflicting evidence)
	or
	(v) only one single study analyzing the causal association is available