Less Toxic Alternatives in Solvent Applications

PPRC has several projects and presentations demonstrating alternatives for some of the higher-toxicity solvents used in industry and the service sector. Solvents are valuable in parts cleaning and degreasing, most often to prepare metal or plastic or composite part surfaces for a coating, plating, etching, or other treatment.    Other solvent applications include, but are not limited to:

  • Paint, coating, and varnish stripping

  • End-product cleaning (e.g., printed circuit boards, metal tubing)

  • Line cleaning (e.g., spray and powder coat lines)

  • Anti-spatter

  • Release agents for molds

  • Equipment cleaning (e.g., printing equipment)

  • Graffiti removal

  • Dry cleaning/Garment cleaning

Halogenated solvents have been historically popular because they are relatively inexpensive, yet effective in removing a wide range of contaminants.  The make-up of halogenated solvents is usually relatively simple molecules that contain a halogen, either  chlorine, fluorine, bromine, or iodine.  Halogenated solvents pose some of the higher toxicity risks to humans and the environment, and are more heavily regulated than many other alternatives. Other cleaning, degreasing, stripping, and/or garment cleaning ingredients include the list below, but some also present health and environmental hazards.  

 

Aqueous Solvents


·  Acidic aqueous
·  Alkaline aqueous
·  Neutral aqueous
·  Caustic
·  Enzymatic-microbial
·  Powdered detergent
·  Water (often heated)

 


Bio-based Solvents


·  Terpenes
·  Esters (including soy-based)
·  Alcohols
·  Glycol ethers
·  Ketones
·  Petroleum distillates
·  Volatile methyl siloxane compounds
·  Dimethyl sulfoxide (DMSO)
·  Volatile methyl siloxane
·  Semi-aqueous, containing bio-based solvents
·  Semi-aqueous, containing terpenes and/or esters

While most of these pose lower toxicity than halogenated solvents/solvent formulations, some are also chemicals of concern. 

Hazards and impacts evaluated in alternative assessments are human toxicity (e.g., cancer, endocrine, tissue, organ, developmental or reproductive toxicity and more), and environmental toxicity (e.g., aquatic, persistence and bioaccumulation, flammability, and global warming potential).   

Routes of exposure are also important.  For instance, solvents that have high volatility, and those used in aerosol form can increase exposure risks through inhalation.   Many solvent chemicals have capability for dermal absorption, and eye and skin irritation or corrosivity.

Human and environmental hazards and presence of individual chemicals on certain regulatory lists on several common solvent ingredients, including halogenateds, are  shown below.  The information is only specific to each single ingredient, so blends and multi-ingredient formulations are not captured in this infographic. 

Projects & Reports on Solvent Alternatives

  • Case Studies:  Vapor Degreasing Conversions to Safer Alternatives.  Katy Wolf, Ph.D.  October 2021.  (Presentation slides)

  • Safer Alternatives for Solvent Applications.  Katy Wolf, Ph.D.  May 2021.  (Recorded presentation) 

  • Safer Alternatives to Vapor Degreasing.  Katy Wolf, Ph.D.  May 2021.  (Recorded presentation)

  • Safer Alternatives and Initiatives in the Garment Cleaning Industry.  Katy Wolf, Ph.D., King County, and Washington State Department of Ecology.   March 2020.  (Recorded webinar)

  • Guide to Finding Safer Alternatives in Surface Cleaning Operations  (TURI, 2021)

  • Ecology’s Product Replacement Program (PRP) for Auto Degreasers and PERC drycleaning.  (Washington State, 2020)

  • Safer Paint and Coating Strippers/Removers (PPRC, 2020)

  • Leech Lake Band of Ojibwe – Safer Degreasing Products  (MnTAP, 2021)

  • Alternative Compliance Strategies for Open Top Vapor Degreasers under a Prohibition of Trichloroethylene (Wolf, 2016, Prepared for Abt Associates)

  • Assabet Valley Technical High School Auto Technology Program Switches to Bio-Based Degreasers (TURI, 2018)  

Presentations & Webinars on Solvent Alternatives

Related Resources & References