One option is to use existing chemicals, but at greater dilutions.

一个选择是利用现存的化学物质，但是要大量的稀释。

youdao

As a big country in producing and using chemicals, there are thousands of chemicals being marketed in our country, but the environmental management of existing chemicals still falls behind.

作为化学品生产和使用的大国，我国市场上流通的化学品数以万计，但是针对现有化学品的环境管理尚处于落后阶段。

youdao

There is no cure and existing drugs, which raise levels of key brain chemicals, do not work for everyone and their effects wear off over time.

没有药物能治愈它，也没有药物对此有长期疗效。 那些提升大脑关键化学成分的药物不是对每个人都适用，而且它们的药效也会随着时间流逝而减弱。

youdao

And there are existing methods, like a machine that can quickly identify chemicals in pills to confirm if the pills are real.

VOA: special.2010.03.01

The drug, Avastin, could hit the market by year-end, joining existing anticancer chemicals and radiation as standard therapy for colon cancer--and it could end up working against other cancers.

FORBES: Magazine Article

And absent a price on carbon, biomass-based chemicals and fuels need to be less expensive than existing products, not at price parity.

FORBES: Strategic Investor To Green Tech Startups: Get A Grip

Critics of existing scrubber technology however point out that the technology only removes the toxic chemicals from the atmosphere at the expense of depositing them in the ocean as contaminated waste water.

CNN: Shipping looks to clean up its act