Anthropogenic hazards are those hazards caused directly or indirectly by human action or inaction. They can be contrasted with natural hazards. Anthropogenic hazards may adversely affect humans, other organisms and biomes and eco-systems. The frequency and severity of hazards are key elements in some risk analysis methodologies. Hazards may also be described in relation to the impact that they have. Environmental hazards may be very different from human hazards. A hazard only exists if there is a pathway to exposure. As an example the center of the earth consists of molten material at very high temperatures which would be a severe hazard if contact was made with the core. However, there is no feasible way of making contact with the core, therefore the center of the earth currently poses no hazard.