As summer finally rolls in, most of us are eager to shed our layers and splash in the surf or hike through the woods. Along the way, we might slap on some SPF 30 sunscreen to ward off skin cancer and hose down our arms and necks with skeeter repellent. But rather than go wild with DEET and just any old high-SPF sunscreen, it's best to consider some potential health and environmental hazards first. Here follows a look at some of the more problematic products and their less-toxic alternatives. Bug Repellent The mosquito cost. Photo: Centers for Disease Control. Insect …