We've been seeing Nellie's dryer balls and their various knockoffs throwing around their purportedly eco-friendly clout everywhere lately, even on green shopping sites and environmental blogs we know and love. (We even tried to correct these misguided claims on one of those deal-a-day sites, but our comments were deleted and ignored. Dude, harsh.)
The concept behind them is well-meaning: The dryer balls are meant to take the place of fabric softeners, which recent studies have revealed contain cancer-causing and neurotoxic solvents such as toluene and styrene. What the manufacturers fail to mention, however, is that the the polyvinyl chloride (PVC) material the supposedly "nontoxic" dryer balls are made of is one of the most poisonous plastics ever created, posing great environmental and health hazards in its manufacture, product life, and disposal. Hydrochloric acid, cancer-causing dioxins, and other persistent pollutants are spewed into the air, water, and land when PVC is being manufactured, resulting in chronic and severe health problems such as cancer, neurological damage, endometriosis, neurological damage, birth defects, and liver and kidney damage. The dioxin exposure of the average American far exceeds the usual standard for acceptable risk; dioxins also concentrate in breast milk, with babies now receiving high doses at orders of magnitude greater than those of the average adult.
Toxic additives and chemical stabilizers such as lead, cadmium, and di(2-ethylhexyl) phthalate (a suspected carcinogen that is known to cause a host of reproductive and developmental defects), leach, flake, or off-gas from the PVC throughout its life. (Nellie's Dryer Balls are also made in China, which hasn't had the best record of late with lead safety.)
And because PVC cannot be easily recycled, it's either landfilled, where it leaches chemicals or incinerated, releasing dioxin and heavy metals again.