Yes, you can touch it with bare hands and nothing dramatic happens. Short diatomaceous earth skin contact still has a price. The National Pesticide Information Center reports that brief exposure causes skin irritation and dryness. A fast scoop out of the bag feels nothing like an hour of dusting a garden bed. Put on gloves for any job that keeps the powder on your skin.
My palms went tight and papery an hour into dusting seed trays on the potting bench. The skin over my knuckles felt sanded. One wash at the outdoor tap did not bring it back, and the powder kept sitting in the creases of my fingers, so I pulled on nitrile gloves for the rest of the trays and kept them on until the bench was clear.
What gardeners call diatomaceous earth skin irritation shows up as a chalky, drawn feeling across the fingers and the back of the hand. NPIC records the irritation and the dryness, and it stops there. The powder kills insects by pulling the oils and fats out of the cuticle of their exoskeleton, so bugs dry out and die. Your hand is not an insect, and the sources never tie the two together. Take dry skin as dry skin and leave the mechanism out of it.
The animal work reads better than most people expect. Rabbits given the powder on their skin five times a week for three weeks showed no health effects. Some registered products are cleared for use straight on dogs and cats, which tells you how ordinary this kind of contact is. Your eyes are the soft spot. The material is abrasive to eyes, and the usual mistake is wiping sweat off your forehead with a dusty hand.
Airborne dust is the exposure the sources spend the most words on. Breathing it in irritates the nose and nasal passages, and large amounts can bring on coughing and shortness of breath. On the cancer question, IARC puts amorphous silica in Group 3, which means not classifiable as to its carcinogenicity to humans. Crystalline silica from work exposure sits in Group 1. Those are two listings for two forms of silica, so read the bag and know which one you bought.
Time in contact matters more than the touch itself. A few seconds with your fingers in the bag is a different exposure from a long session with a duster. The long sessions are the ones that leave hands dry and irritated, and they also put the most powder in the air around your face. The fact sheet behind this answer records both of those effects and no more. It puts no clock on how long either one lasts, so watch your own hands. Gloves at the start are the cheaper trade.
Handling diatomaceous earth safely comes down to a few plain habits. Glove up when the job will run longer than a quick scoop, and keep your hands off your face until you have washed them with soap and water. Pour low and slow so the powder does not plume up at you. Outdoors, stand with the wind behind you. Indoors, crack a window before you start.
Treat the airborne dust as the exposure that matters most. Pour close to the ground, keep your face out of the cloud, and wash your hands before you touch your eyes.
One bare handed scoop into a crack under the sink is not worth a second thought. Treating a whole raised bed is the job that dries and irritates the skin, and it earns gloves and a dust mask. The dryness eases once you stop handling the stuff. Eyes and lungs are where I keep my guard up.
Read the full article: Diatomaceous Earth: What It Really Kills
