6PPD is an organic chemical widely used as stabilising additive (or antidegradant) in rubbers, such as NR, SBR and BR; all of which are common in vehicle tires.

[2] It has been used in rubber since the late 1970s,[3] but has been the subject of increasing scrutiny since 2021, when it was determined that its oxidation product (6PPD-Q) causes pre-spawn mortality in coho salmon.

[19] The Nisqually and nonprofit Long Live the Kings installed a mobile stormwater filter at a bridge in the Ohop Valley in 2022.

[20] 6PPD itself is deadly to rotifers, especially in combination with sodium chloride, though not at the level generally found in the runoff from road salt.

[21] A small-scale biomonitoring study in South China has shown both 6PPD and 6PPDQ to be present in human urine; concentrations were low but the health implications are unknown.