Tell you the truth, I was aware long time ago since I worked in Manufacturing that Sothorn workers are mixed with Thai and non-Thai but I did not pay attention even today because they just perform simple work and there man-hours are not counted in our Bangpakong man-hours. The most importance is , from my perception, EOHS Standards do not require these persons for training, just only wearing proper PPE.
By the way, I'm glad to hear inputs from EOHS perspective. I love continuous improvement.