Why has dimethyl phthalate (DMP) disappeared from mainstream mosquito repellent markets?

Why has dimethyl phthalate (DMP) disappeared from mainstream mosquito repellent markets?
Dimethyl phthalate (DMP), once a common active in mosquito repellents, has been largely phased out of household insect control in China. The rise of DEET, pyrethroids, and phenylpyrazole insecticides displaced it decades ago. Today, DMP's main commercial role is as a plasticizer in non-agricultural applications. However, it retains a niche in bird repellent formulations, where it works through sensory irritation rather than toxicity. Its standalone efficacy is weak—studies show repellency below 50% even at doses exceeding 0.4% of seed weight—but as a synergist with agents like thiram, it significantly boosts overall repellency and extends duration. This dual identity—marginalized in one market, valued as an adjuvant in another—explains its current low-profile but persistent demand.