Best practices to pass in Conditions to Rake task?

I'm trying to pass in conditions to a find command in a rake task. I'm
still a little new to this, but what is the best practices for this?
Should I be passing in a hash or.. Any suggestions welcome!

command line: rake mytask conditions='condition = 1'

#mytask.rake
def conditions
  ENV['conditions'] || ENV['conditions'] || nil
end

task :metadata => :environment do
  klass.find_each(:start => start, :conditions => conditions) do

record>

  #do stuff
  end
end

thanks!