Would the river be this brown without deforestation and mining? Is the subject standing in this water?
When in the past I have been around toxic substances, especially liquids like solvents and the like, I have interacted with this material in the anthropoligical sense of the taboo. Your interest in masculinity raises the question of toxics of the body, rather than just toxics outside the body. By that I mean public health discourse about both disease-bearing living pathogens and waste products. The way these men spoke so callously about the mercury's beauty reminds me of this recent trend in masculinity, both straight and gay, to celebrate and to cherish men's semen. This I've seen described in visual studies analyses of pornography, the "cumshot" phenomenon, etc. One theory is that this sudden focus on semen has to do with fears of STIs like HIV and resulting anxieties. One starting point for exploring these types of questions would be Julia Kristeva.
Toxic masculinity! Toxic humanism! Right on, that's clever, but go ahead and make the message even more explicit. This is where photo alteration can add even more to your work. Look for some of those horrific bullfighting images you see circulating in the PETA circles online. More people should see what the killing of their food looks like anyway. But even more importantly, teach people to make connections between the brands around them all the time and visual association. I'm writing this on a MacBook right now, a machine that came with the image of an apple with a bite taken out of it. I tend to hate all the stupid Christian imagery around me that I have to deal with, but this Edenic reference on my computer got to be a bridge too far. I covered it with a sticker like many a hipster type. Quite the digression, but this is my way of illustrating what work you can do toward building critical awareness about the toxicities in our lives and the ways they mutually constitute one another. Feminist geography might be helpful for you if you want to go further with this - see Doreen Massey.
My favorite thing about the succession of images from number 1 to number 2 is the way the upper greyness and lower redness rhymed. The two business services purport to do absolutely opposite work (cleanup vs. pollution) and yet the accidental convergence of design illustrates how they are both invested in sustaining the same negative ecological paradigm. Bravo! That said, the shift from two portraits to a landscape is disorienting. I'd stick with portrait for the third, which you can do simply by editing the third into a portrait. Also, cut off that white strip on two edges of this image.