Arlene: Can you clarify your question a bit for me. What aspect of "sustainability" are you referencing (the sustainability of modern slavery as an illegal labour resource; environmental sustainability that is adversely impacted by modern slavery; the impact of modern slavery on food security sustainability, etc.)?  I'd like to chime in on this topic, but want to make sure I'm addressing your root question.

None of the above: you cannot have environmental sustainability IF it does not look at modern slavery. I believe you cannot have sustainability (of any type--local, supply chain, etc.) if you do not look at, consider, modern slavery. So, the latter is my question: is anyone working with sustainability in such a way that it argues for modern slavery being considered as part of sustainability, as needing to be addressed in that context.