Dairy farming was initially rated as one of the highest-risk industries during health and safety reforms before the Labour Minister, Michael Woodhouse, intervened and changed the criteria, documents show.
Under fiercely-debated law changes in August, "high-risk" businesses cannot be exempted from a key requirement to have a health and safety representative if a worker requests one, even if they have fewer than 20 employees.
Documents released under the Official Information Act reveal the process for determining which industries would be classed as high-risk.
In the first list produced by Worksafe officials for the minister, which was based on the industry standard ANZSIC Level 2 figures, agriculture was in the highest category.