Here is a number that should reorder how you think about this entire category.
In a 2021 life-cycle assessment of a plant-based shampoo, researchers tested refill options against the standard bottle. Buying refills from a large reusable canister or a lightweight pouch cut the shampoo packaging’s global warming impact by about 70 percent. Across the product’s whole life, that same change moved the global warming potential by about 2.5 percent.
Seventy percent off the visible part. Two and a half percent off the actual total. The packaging was never where the weight was.
That gap between what gets marketed and what gets measured runs through almost every environmental claim on a personal care shelf. This article is about what the measurements say.
What a life-cycle assessment measures, and why the setup decides the answer
A life-cycle assessment, or LCA, adds up the environmental effects of a product from raw material through manufacture, transport, use and disposal. It is the most honest tool available for this question. It is also easy to steer.
The steering happens in two places. The first is the system boundary: how far upstream and downstream you count. The second is the functional unit: the thing you are measuring per.
The functional unit sounds technical and is not. The European Commission’s Joint Research Centre, revising the EU Ecolabel criteria for soaps and shampoos in 2012, chose one gram of active content as its functional unit rather than a standard dose. The reason it gave is worth sitting with: the choice was made to avoid giving more diluted products an advantage over more concentrated ones. Measure per bottle and water looks free. Measure per gram of what does the work and it does not.
The 2021 shampoo study measured per hair wash. That single decision is what pulled hot water into the accounting, and hot water is what the study found dominating.
Article 741 walks through the same lesson in food, where a dataset covering 38,700 farms shows how boundary choices change the answer. The principle transfers exactly. Before you accept a footprint figure, ask what it is a footprint of, and per what.
One more caveat that applies to everything below. Every one of these studies is a specific product in a specific country with a specific electricity grid and water-heating mix. They show direction reliably. They do not transfer as exact numbers.
The hot water, not the bottle
The 2021 study, by Hanna Kröhnert and Matthias Stucki in the journal Sustainability, is the clearest single piece of evidence on this. Its finding is flat: the use phase is the dominant life stage for every impact category examined except land use.
What drives the use phase is heating shower water. Natural gas heating contributed roughly 34 percent and oil heating roughly 25 percent, each figure applying to both climate change and energy resource use. The ingredients mattered most in exactly one category, land use, where they contributed 57 percent. Packaging’s largest single contribution anywhere was 23 percent of freshwater ecotoxicity.
Then the refill result described above: about 70 percent off the packaging impact, about 2.5 percent off the whole-life global warming potential.
A fair objection is that this is one liquid shampoo in one European market. So look at a solid product, measured independently. A 2023 cradle-to-grave LCA of washing bar soap by Gaurav Gaurav and colleagues, also in Sustainability, found that eutrophication, the nutrient loading that drives algal blooms, carried the highest environmental burden of any category it measured. The largest contributor to that was the use phase, at 76.5 percent, driven by the greywater that goes down the drain.
Different product, different format, different impact category, same structural answer. The bar does not escape the use phase either, because the use phase is mostly water and what you do with it.
There is an older regulatory observation underneath this. That JRC working document describes these as rinse-off products that are released entirely to water during or after use. Everything you put on in the shower goes into the drain by design. The container is the part that stays behind, which is why it feels like the environmental question. The measurements say it is the minor one.
The practical consequence is a reordering, not a new chore. If you want the measured lever on a shampoo’s footprint, it is shower length and water temperature, and it is not close. Article 747 covers packaging materials and the trade-offs between them, which is a real question with a different answer.
The supplement bottle, and the trip to the shop
Supplements get a cleaner test, because somebody measured the packaging options head to head.
A 2023 study in Science of the Total Environment by Margot Cooreman-Algoed and colleagues at Ghent University ran a cradle-to-grave LCA on chewable vitamin B12 supplements in four packaging types: blister packs and bottles of HDPE, PET or glass. The functional unit was a recommended daily dose delivered to a Belgian consumer.
Two results break the usual assumptions.
First, the carbon footprint was dominated by two things that are not the package: the consumer’s transport to the pharmacy, and manufacturing the active ingredient in China, even though that ingredient is about 1 percent of the supplement’s mass. Where the ingredient was made mattered a lot. Manufacturing the same powder in France came out 22 percent lower.
Second, the ranking of containers runs against intuition. HDPE bottles were lowest at 6.3 grams of CO2-equivalent. PET came in 1 percent higher, glass 8 percent higher and blister packs 35 percent higher. Glass feels like the responsible choice. In this measurement it was not.
A safety note that no footprint claim covers. An environmental choice is not a safety check. The CDC’s Yellow Book states that the two major safety concerns about dietary supplements are potential drug interactions and product contamination, and that analyses of supplements sometimes find differences between labeled and actual ingredients. If you take prescription medicines, the right person to ask about a new supplement is your prescriber or pharmacist, before you buy, regardless of what the bottle is made of. Article 677 covers interactions in detail.
The comparison nobody has published
You have been told that a shampoo bar beats a bottle. Here is the state of the evidence on that.
A search of the peer-reviewed literature for this article did not turn up a credible head-to-head life-cycle comparison of solid versus liquid shampoo. The bar soap study above does not compare formats; it studies bar soap alone and says so. The claim that bars dramatically outperform bottles circulates almost entirely on retailer blogs and search-optimized buying guides, which are not evidence.
That does not mean bars are worse. It means the comparison is unverified in either direction, and anyone telling you the size of the saving is telling you something nobody has measured.
What the literature does support is that the choice probably matters less than it feels like it should, because the use phase dominates both formats, and a bar still gets used under hot running water.
On this library’s evidence tiers, “solid beats liquid” is insufficient evidence, not preliminary research. There is no study to be preliminary about.
Microbeads: a narrow US law and a much wider EU one
Most people believe the United States banned microplastics in cosmetics. Read the statute and the belief does not survive.
The Microbead-Free Waters Act of 2015, Public Law 114-114, was signed on 28 December 2015. It defines a plastic microbead as “any solid plastic particle that is less than five millimeters in size” that is intended to exfoliate or cleanse the human body. It prohibits manufacturing and interstate commerce in rinse-off cosmetics containing intentionally added plastic microbeads, and it specifies that rinse-off cosmetic includes toothpaste. The deadlines ran from 1 July 2017 for manufacturing through 1 July 2019 for the last covered category.
Now read what is missing. Three conditions all have to be met: rinse-off, cosmetic, and plastic particles intended to exfoliate or cleanse. So the law does not reach leave-on cosmetics, make-up, glitter, microplastics added as film-formers or opacifiers or texturizers, household cleaners or industrial abrasives. It also sets no biodegradability standard, so a particle marketed as biodegradable is covered or not depending on whether it is a solid plastic particle, not on how fast it breaks down.
Two federal pages describe the law more broadly than it reads. The FDA’s FAQ page renders the size threshold as 5 millimeters or less, where the statute says less than five millimeters. NOAA’s National Ocean Service page, updated on 23 September 2026, describes the Act as banning plastic microbeads in cosmetics and personal care products, which is wider than the statutory phrase “rinse-off cosmetic.” The statute is the law. Both federal summaries are worth knowing about, because they are where most secondary writing picks up its version.
The European Union took a different approach, and a US reader should not assume the two are equivalent. Commission Regulation (EU) 2023/2055 restricts synthetic polymer microparticles on their own or intentionally added to mixtures, with no test of what the particle is for. The general prohibition applied from 17 October 2023. Transition periods run to 16 October 2027 for rinse-off cosmetics, 16 October 2029 for leave-on cosmetics and 16 October 2035 for make-up, lip and nail cosmetics, with those last products required to carry a label stating they contain microplastics from 17 October 2031. Loose plastic glitter was banned from 17 October 2023 for uses without a transition period.
Function-agnostic, and running more than sixteen years past the US law’s final deadline. A product sold in both markets can comply with US law and still contain microplastics the EU is phasing out.
Palm oil, and what a private roundtable can and cannot do
Palm oil and its derivatives sit in a large share of soaps, cleansers and cosmetics. The bar soap study above identifies its primary ingredient as a sodium salt derived from palm oil.
The assurance scheme attached to it is the Roundtable on Sustainable Palm Oil. Its own statutes, endorsed by its General Assembly on 13 November 2024, establish what it legally is: an international association set up in Zurich under Article 60 of the Swiss Civil Code, a non-profit association uniting stakeholders from seven sectors of the palm oil industry, registered as CHE-111.720.599. Private, voluntary and membership-based. No legal force anywhere.
In this library’s four groups, that is a private third-party certification scheme, not a regulation and not a government program. Article 748 covers how to sort seals in general.
RSPO runs four supply-chain models, and the differences are the whole story. Identity Preserved means certified oil from one identifiable source, kept separate. Segregated means certified oil from multiple certified sources, kept separate from ordinary palm oil. Mass Balance means certified oil mixed with ordinary palm oil along the way. Book and Claim means buying credits from certified growers. A claim on a label can rest on any of these, and they are not the same promise.
The evidence on whether certification works is genuinely mixed, and both halves need reporting. A 2018 study in the Proceedings of the National Academy of Sciences by Kimberly Carlson and colleagues, published 2 January 2018, found a real effect: certification lowered deforestation by 33 percent, from a counterfactual rate of 9.8 percent a year to 6.6 percent. The same study found that “certification had no causal impact on forest loss in peatlands or active fire detection rates.” And it noted that most plantations contained little residual forest by the time they were certified, which limits how much forest certification could have saved.
Governments treat the models unequally, which tells you something. Commission Decision (EU) 2021/1870, setting EU Ecolabel criteria for cosmetic products, requires 100 percent of renewable ingredients to meet sustainable production requirements. For palm oil and palm kernel oil it accepted identity preserved, segregated and mass balance until 1 January 2025, and only identity preserved and segregated after that date. For derivatives, mass balance is still accepted. Book and Claim is not accepted anywhere in that criterion.
Binding law is coming in the EU, slowly. The EU Deforestation Regulation applies from 30 December 2026 for large and medium operators and 30 June 2027 for micro and small operators, with micro and small operators already covered by the older timber regulation on the earlier date. It has been postponed twice, most recently by a regulation published in December 2025, and a further delegated regulation extends scope to additional products from 30 December 2027. None of it binds products sold in the United States.
The ingredients with a documented supply problem
Mica, and the difference between a coalition and a certification
Mica gives cosmetics their shimmer. The US Department of Labor’s Bureau of International Labor Affairs lists it in the List of Goods Produced by Child Labor or Forced Labor, in the 2024 edition current as of 5 September 2024.
The category matters and is often overstated. Mica from India and mica from Madagascar are both listed under child labor, not forced labor. For India, the Department reports children mining in the major mica-producing states of Bihar, Jharkhand and Rajasthan. For Madagascar, it reports that children aged 3 to 17 produce mica and that adolescent boys dig mines and risk injury from falling rocks. On the same page, oleochemicals from Indonesia and Malaysia carry a different and broader label: inputs produced with child labor and inputs produced with forced labor.
The industry response is the Responsible Mica Initiative, which describes itself as a multi-stakeholder coalition for action, created in 2017 by companies in the mica supply chain and civil society organizations, with more than 70 organizations committed. Its three pillars each carry a 100 percent target for Bihar and Jharkhand, covering workplace standards, community programs and a legal framework.
Two things to notice. The targets carry no completion dates. And the initiative does not describe itself as a certification scheme, because it is not one. In the four-group sort, it is a private commitment, which is the weakest of the four for a consumer trying to verify anything.
Essential oils and the plants behind them
Three species show what the documentation looks like, and how differently each one is handled.
Brazilian rosewood, Aniba rosaeodora, was added to CITES Appendix II at the 2010 conference in Doha, with the amendment taking effect on 23 June 2010. The annotation attached to the listing covers logs, sawn wood, veneer sheets, plywood and essential oil, excluding finished products packaged and ready for retail. So the oil itself is controlled in international trade, and the bottle on the shelf is carved out of that control.
For Indian sandalwood, Santalum album, the documentation is scientific rather than treaty-based. A 2024 review in Discover Applied Sciences records that the species entered the IUCN vulnerable category in 1997, that Indian production fell from 4,000 tons a year in the 1960s to 500 tons in 2007 and about 350 tons by 2014, that average auction prices climbed more than 600 percent, and that it has been reported commercially extinct in parts of its range. Heartwood oil from it goes into perfumes, cosmetics, soaps and toiletries.
Frankincense from Boswellia papyrifera has the starkest field data. A 2019 study in Nature Sustainability led by Frans Bongers found evidence of population collapse, with over 75 percent of studied populations lacking small trees and natural regeneration absent for decades. The projection: frankincense production halved within 20 years. The United States brought that evidence to the CITES Conference of the Parties in Geneva in August 2019, as an information document whose recommendations were conservation and restoration measures rather than a trade listing.
Article 757 covers harvest pressure on individual species in depth. The point here is narrower: “natural” and “plant-derived” carry no information about whether the plant can sustain the demand, and the trade controls that do exist are species-specific and sometimes stop short of the finished retail bottle.
Three checks, and the one thing to take away
Built for this article.
1. Ask what the claim is a claim about. A recyclability mark describes the container. An ingredient claim describes the formula. Neither describes the product’s measured life-cycle footprint, and in the studies above those are the small part.
2. For palm oil, ask which supply-chain model. Physically segregated oil, mixed oil under mass balance, and a purchased credit are three different promises wearing one word. If an operator cannot tell you which, the claim is not checkable.
3. Change the water before you change the bottle. The use phase is where the measurements land, for liquids and for bars. Shorter and cooler is the lever the literature supports.
The single most useful finding here is the one that costs nothing to act on and gets almost no marketing behind it: for rinse-off personal care products, the energy that heats your water outweighs the container, repeatedly, in independent studies that were not looking to prove it.
And the honest answer to the bar-versus-bottle question is that there is no answer yet. Nobody has published the comparison. Anyone who gives you a number for it made it up or repeated someone who did.
Sources
- US Government Publishing Office (govinfo). “Public Law 114-114, Microbead-Free Waters Act of 2015, enacted 28 December 2015 (statutory text).” govinfo.gov
- US Food and Drug Administration. “The Microbead-Free Waters Act: FAQs (content current as of 25 February 2022).” fda.gov
- National Oceanic and Atmospheric Administration, National Ocean Service (page updated 23 September 2026). “National Ocean Service ocean facts page on microplastics.” oceanservice.noaa.gov
- European Commission, DG Internal Market, Industry, Entrepreneurship and SMEs (page updated 18 July 2025). “Commission Regulation (EU) 2023/2055: restriction on microplastics intentionally added to products.” single-market-economy.ec.europa.eu
- EUR-Lex, Official Journal of the European Union L 379, 26 October 2021. “Commission Decision (EU) 2021/1870 of 22 October 2021 establishing the EU Ecolabel criteria for cosmetic products and animal care products.” eur-lex.europa.eu
- European Commission, DG Environment. “Regulation on deforestation-free products (application dates for Regulation (EU) 2023/1115).” environment.ec.europa.eu
- European Commission, Joint Research Centre IPTS with LEITAT, February 2012. “Kaps R, Kougoulis J, Escamilla M, et al. "Revision of European Ecolabel Criteria for Soaps, Shampoos and Hair Conditioners: Background report including draft criteria revision proposal".” susproc.jrc.ec.europa.eu
- Roundtable on Sustainable Palm Oil. “The Statutes of the Roundtable on Sustainable Palm Oil, endorsed by General Assembly GA21 on 13 November 2024.” rspo.org
- Roundtable on Sustainable Palm Oil. “Supply chains (Identity Preserved, Segregated, Mass Balance, Book and Claim).” rspo.org
- Proceedings of the National Academy of Sciences, 2 January 2018 (open-access author copy, University of California eScholarship). “Carlson KM, Heilmayr R, Gibbs HK, et al. "Effect of oil palm sustainability certification on deforestation and fire in Indonesia." PNAS 115(1).” escholarship.org
- US Department of Labor, Bureau of International Labor Affairs. “List of Goods Produced by Child Labor or Forced Labor, 2024 TVPRA List (mica and oleochemicals entries).” dol.gov
- Responsible Mica Initiative, 2021. “Responsible Mica Initiative flyer (self-description, founding year, membership and three pillars).” responsible-mica-initiative.com
- Sustainability, 2021. “Krohnert H, Stucki M. "Life Cycle Assessment of a Plant-Based, Regionally Marketed Shampoo and Analysis of Refill Options." Sustainability 13(15):8478. DOI: 10.3390/su13158478.” doi.org
- Sustainability, 2023. “Gaurav G, Dangayach GS, Meena ML, Chaudhary V, Gupta S, Jagtap S. "The Environmental Impacts of Bar Soap Production: Uncovering Sustainability Risks with LCA Analysis." Sustainability 15(12):9287. DOI: 10.3390/su15129287.” doi.org
- Science of the Total Environment, 2023 (PubMed, PMID 37302605). “Cooreman-Algoed M, Boone L, Uitterhaegen E, Taelman SE, De Soete W, Dewulf J. "Environmental life cycle assessment of nutraceuticals: A case study on methylcobalamin in different packaging types." Sci Total Environ 893:164780. DOI: 10.1016/j.scitotenv.2023.164780.” doi.org
- CITES Plants Committee, nineteenth meeting, Geneva, 18-21 April 2011. “PC19 Doc. 16.4, Aniba rosaeodora (Appendix II listing, annotation #12 and the working definition of essential oil).” cites.org
- CITES, Eighteenth meeting of the Conference of the Parties, Geneva, August 2019, submitted by the United States. “CoP18 Inf. 54, information document on Boswellia conservation status.” cites.org
- Discover Applied Sciences, 2024. “Chavan SB, Uthappa AR, Chichaghare AR, et al. "Past, present and future of Indian sandalwood (Santalum album) cultivation and commercial prospects." Discover Applied Sciences 6:627. DOI: 10.1007/s42452-024-06337-8.” link.springer.com
- Nature Sustainability, 2019 (Wageningen University & Research repository record). “Bongers F, Groenendijk P, Bekele T, et al. "Frankincense in peril." Nature Sustainability 2:602-610. DOI: 10.1038/s41893-019-0322-2.” research.wur.nl
- US Centers for Disease Control and Prevention, CDC Yellow Book (page dated 23 April 2025). “Complementary and Integrative Health Approaches to Travel Wellness (dietary supplement safety concerns).” cdc.gov