Cooperate means “to work together, to be helpful,” but it has lately also come in certain contexts to mean “go along with, submit, or obey,” as in If you don’t cooperate, we’ll sell out.

Collaborate means “to work together, usually on some project involving mental rather than physical work”: you cooperate in building a house, but you collaborate in writing a musical. You and someone else cooperate or collaborate, or you cooperate or collaborate with someone else.

Collaborate together and cooperate together are redundant, but they may sometimes be useful for special emphasis. from Guide to Standard American English

The most obvious example of how cooperation can reduce the H&S risks, is when it comes to lifting heavy goods. Two people can manouvre much more than a person working alone. Another example is with ladders, with somebody "footing" that ladder.

Examine a work situaion, and spell out how cooperation could reduce risk, for each of the following 

Employer and other Employer

Employer and Employee

Employee and Employee 

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