Fall 2025

Martin Mulvihill
Oct 2
5 min read

6PPD - A Salmon Story

Car tires have 6-PPD, against ozone,

Which in nature breaks down into a quinone.

But when Cohos get near,

Toxic symptoms appear,

Watch your 6!, PPD, you’re alone!

It usually takes industry and regulators years to decades to act on chemicals of concern. As the cases for Bisphenols, PFAS, or Lead have shown, it takes years to establish evidence of harm, and even more years more to explore potential alternatives and create incentives that encourage substitution. The more recent story of 6-PPD is different. The scientific proof has been conclusive, the regulatory action quicker than in the past, and the search for alternatives has started.

In 2021 a researcher from the University of Washington identified 6-PPD-quinone as a primary cause of acute mortality in spawning Coho Salmon. 6-PPD-quinone is created when ozone reacts with 6-PPD from car tires. 6-PPD is added, at low percentage levels, to rubber tires to prevent oxidation and degradation. Without 6-PPD, the tires would harden and crumble within months.

The response of advocates and regulators has been commensurate with the urgency. Washington State Ecology, California EPA, and the Federal EPA have released action plans to address the impact of 6PPD on aquatic ecosystems. The regulatory agencies stop short of banning 6-PPD but they are incentivizing the development of alternatives. California has also listed 6-PPD in tires as a priority product under the Safer Consumer Products Act, which could lead to restrictions after the alternatives assessment process is complete.

The tire industry has been active in the search for alternatives. The US Tire Manufactures Association has created a consortium to identify a potential alternatives to 6PPD that is protective of motorist safety and the environment. Flexsys, a rubber additives company, also recently announced a partnership with the USDA to develop a safer alternative. The work at the USDA was done in partnership with the Berkeley Center for Green Chemistry, where safer alternatives were identified as a part of the center’s Greener Solutions class.

We expect that the search for 6PPD alternatives to yield safer alternatives that could be applied across all the uses of phenylenediamine (the PPD in 6-PPD) derivative chemicals, including not just tires, but also hair dyes, textile dyes, and adhesives.

Toxicity Due Diligence

Every investment causes some material exchange, use, transformation, or consumption. Early-stage investors support businesses that aim to grow large, with a commensurate impact on the world. The potential toxicity of the chemicals and materials new businesses bring into existence may increase their risks and affect their success. Using safer, sustainable alternatives can lower their regulatory barriers, improve efficiencies, and create brand differentiation.

Understanding the chemistry and materials aspects of an investment should be a part of regular due diligence. Investors should understand the chemical composition, chemical hazards, process hazards, restricted substance lists, regulatory compliance, and safer alternatives involved. Investors should ask chemical‑hazard questions, request materials disclosure, and encourage prospective and portfolio companies to use the green chemistry design approach.

The following list of questions are a starting point for conversations between investors and early-stage companies:

Is there a complete chemicals and materials inventory?
Is there a chemicals management strategy?
Is the company using a design approach for its chemistry and materials work?
What are the relevant Restricted Substance Lists for the company’s products?
Have any hazardous end points been identified?
Are there safer alternatives to the hazardous chemistries used?
Are there any hazardous process conditions?
What type of, and how is, waste generated and managed?
What type of packaging does the company use?
Are there appropriate measures and policies to ensure workplace safety?
Is the company in compliance with the relevant regulations for its processes and products?
What are the relevant product Certifications?
Have any Life Cycle Assessments been conducted?
Are there any competitive advantages the company may enjoy from using safer chemistries and a design approach?

For more details read our recent article.

Safer Made Event in San Francisco: Investing in Safer Chemistry

Join us in San Francisco on November 5^th for a conversation about investing in safer chemistry. After seven years of pioneering early-stage investments in safer chemistry innovation, we look forward to sharing what we have learned along the way, and discuss how can we further support detoxification and the adoption of safer chemistries and materials.

This will be an interactive session focused on sharing insights, discussing success factors for companies bringing safer products to market, and emerging themes in safer chemistry.

Reserve your spot here.

Financings

Act-ion Battery Technologies makes cleaner cathode materials for batteries, and raised $4 million.

Alchemy creates next-generation coatings, and raised $6 million.

Amogy makes ammonia-based power systems, and raised $23 million.

AMSilk makes biodegradable silk-based biomaterials that can be turned into fibers, powders, hydrogels, and coatings for use in textiles, and consumer products, and raised $34.5 million.

Atomionics makes quantum gravimetry sensors to speed mineral discovery, and raised $12.7 million.

BIOWEG turns agricultural waste into biodegradable replacements for microplastics using bacterial cellulose, and raised $19 million.

BoobyBiome is developing supplements that preserve the beneficial bacteria in breast milk and adds key strains to formula-fed infants, and raised $3.4 million.

CuspAI uses AI to accelerate the discovery and development of new materials, and raised $100 million.

ChemFinity develops sorbent-based filters that can selectively recover critical minerals like rare earths, platinum group metals, and copper from complex waste streams, and raised $7 million.

Debut develops biotech-based ingredients for beauty, health, and wellness products, replacing traditional chemical processes with lab-grown alternatives, and raised $20 million.

DISA Technologies builds dry mineral separation systems that let mining companies recover valuable metals from waste rock without using water or chemicals, and raised $30 million.

enaDyne develops plasma catalysis reactors to convert CO₂ into chemicals, and raised $8.2 million.

EnsiliTech is developing a silica-based method that keeps vaccines and biologics stable at room temperature, eliminating the need for refrigeration during storage and transport, and raised $6.1 million.

Genomines produces battery-grade nickel through plant-based metal extraction, and raised $45 million.

Lila Sciences automates experiment design and accelerate discoveries in medicine, chemistry, and materials, and raised $235 million.

Nitricity produces organic nitrogen fertilizer using renewable energy and agricultural waste, and raised $50 million.

Noxilizer provides nitrogen dioxide sterilization for pharmaceutical, biotechnology, and medical device products, and raised $30 million.

Nxtfood makes plant-based meat alternatives from locally grown wheat and pea proteins, and raised $57.9 million.

Prefer uses fermentation to transform food manufacturing byproducts into sustainable coffee and cocoa flavors for the food industry, and raised $4.2 million.

Rock Flour Company uses ultra-fine powder created when glaciers grind against bedrock to improve soil fertility and capture carbon, and raised $7.2 million.

Scindo develops enzymes to create sustainable alternatives to petroleum-based chemicals, and raised $5.4 million.

Terra Oleo develops microbes to transform agricultural waste into oils for use in cosmetics and pharmaceuticals as a sustainable alternative to palm oil, and raised $3.1 million.

Waterly software helps water and wastewater utilities digitize regulatory reporting, sampling, and asset data management, and raised $4 million.

Woodchuck develops tools to identify, sort, and convert wood waste from construction and manufacturing sites into renewable biomass fuel, and raised $3.8 million.

Xampla makes plant-based materials to replace single-use plastics that are water soluble, and raised $14 million.

XL Batteries develops non-flammable, long-duration organic flow batteries, and raised $7.5 million..