Superfund clean-up disputes are difficult to resolve because they involve multiple issues in addition to multiple parties. Environmental Protection Agency (EPA) and waste generator negotiators often disagree about how to interpret technical or scientific information. Examples of difficult issues include company shares of the clean-up cost, potential threat to groundwater, and what environmental standards apply to clean-up; "how clean is clean" is not at all well understood. Industry typically focueses on fairness of the allocation of cost and liability and the cost and responsibility for clean-up.