Table 2.

Estimated magnitudes of contamination sources in milk, egg and meat production systems.

Components along the food chain of animal products	Milk production		Egg production		Meat production
	Indoor1	Outdoor2	Indoor	Outdoor	Indoor	Outdoor
Air (inhalation)	+	+	+	+	+	+
Soil	+	+++	0	+++	0	+++
Water	+	+	+	+	+	+
Worms and insects	0	0	0	++	0	+
Roughages 3	++	+++	0	+	++	+++
Domestic waste	0	0	0	+	0	0
Compound feed	+	+	++	++	+	+
Bedding material	+	+	+	+	+	+

¹refers to a production system without outdoor access (e.g., zero-grazing in milk production systems);

²including organic, free range and outdoor production systems;

^+++:high risk;

^++:medium risk;

^+:low risk; and 0: no risk;

³Roughage in meat production systems is mainly provided to produce beef, not for pigs or poultry meat.