Zinc sulfate is a combination of sulfur and zinc. It is an herbicide typically used for moss control. The toxicity of zinc sulfate depends on the amount of zinc in the product. Zinc is an essential mineral for human, animal, and plant nutrition. Zinc can be found naturally in the environment, foods, and water.

Products that contain zinc have been registered for use in pesticide products in the United States since 1973.

Products containing zinc sulfate can be granular, pelleted, tableted, wettable powders, or dusts. Currently there are nine products containing zinc sulfate registered for use in the United States.

Zinc binds to proteins or organic acids in plants. In high concentrations, it affects the growth of moss and other plants, and damages the cells causing them to turn yellow.

You can be exposed if you are applying zinc sulfate and you get it on your skin, breathe it in, or accidentally eat a product. This can also happen if you get some on your hands and eat or smoke without washing your hands first. You can limit your exposure to zinc sulfate by following all label instructions carefully.

Zinc is an essential element and it is required to support the normal function of the human body. Our body adjusts its internal environment to keep zinc levels steady. The zinc in zinc sulfate enters into the body if ingested, inhaled or by skin contact and enters the bloodstream. Once inside, zinc moves throughout the body, binds to proteins, and enters different organs.

Zinc can be found in the bone, brain, heart, intestine, liver, kidney, lungs, muscle, pancreas, prostate, skin, and stomach. Excess zinc is mainly eliminated in the feces; it can be excreted in the urine, sweat, and skin.

Cancer studies in animals exposed to zinc sulfate have resulted in different findings. One study in rats resulted in cancer, in contrast to a study in mice with no evidence of cancer. The U.S. Environmental Protection Agency concluded that there is not enough information to determine whether or not zinc sulfate can cause cancer in humans.

Scientists studied long-term exposure to zinc sulfate in rats and found no adverse health effects. A study in dogs fed zinc sulfate resulted in changes of the blood chemistry. In one study miscarriages were found when pregnant rats were fed zinc sulfate throughout their pregnancies. In other studies, mice, rats, and hamsters were given zinc sulfate during pregnancy and no effects were found.

When people eat too much zinc over a long period of time, it can affect the stomach and intestine, the respiratory system, and the pancreas. It can also interfere with the correct balance of other essential minerals like copper, iron and magnesium. This can cause nutritional deficiencies, and harm the chemical balance between good and bad cholesterol.

While children may be especially sensitive to pesticides compared to adults, there are currently no studies showing that children have increased sensitivity specifically to zinc sulfate.

Zinc salts are slightly toxic or practically non-toxic to birds and highly toxic to freshwater fish and invertebrates. No data were available on toxicity to bees. Bees and other pollinators are not likely to be harmed because they do not eat much plant material.