Microbiological Quality Of Consumer Products

May 3, 2011

The Consumer Specialty Products Association surveys the practices used to ensure microbiological quality of household and institutional products by focusing on raw material controls, finished product quality and process hygiene.

Microbiological Quality Of Consumer Products

The Consumer Specialty Products Association surveys the practices used to ensure microbiological quality of household and institutional products by focusing on raw material controls, finished product quality and process hygiene.



Microbial integrity is a critical quality element for many consumer products. For foods, drugs and cosmetics, microbiological quality finds a considerable body of practical knowledge, especially concerning raw material control, finished product testing and manufacturing hygiene.1,2,3

In addition to the good efforts of the respective industries, potential health risks due to gross microbial contamination have the attention of regulatory bodies around the world that address these via recalls and bans of the offending product.4,5

For household products such as cleaners, detergents, fabric softeners and air fresheners, microbial quality is typically not a concern as public health risk due to contamination is not so evident. The most likely consequence of microbial contamination would be compromised product quality and performance. Technical reports of microbial contamination of household and related products have been relatively rare as have health-related recalls of contaminated household products.6,7,8,9

Most surprising are the fortunately infrequent reports of contaminated disinfectants.10,11 The rarity of such reports is probably attributable to product formulation characteristics that often mitigate microbial risk including high surfactant levels, solvents, pHs closer to the boundaries for microbial growth, chelators and, for some products, disinfectant actives. These historically have been sufficient to minimize the occurrence of contaminated household products. In recent decades, many of these barriers have been diminished if not eliminated by regulations limiting solvent use12 and efforts to formulate with green and environmentally-sustainable components and processes.13

Despite the trend toward less hostile formulations, it is somewhat of a surprise that there has not been an increase in the occurrence of microbial contamination of household products. Although microbes can adapt to grow in fairly radical physical and chemical environments, microbial issues in household and similar products appear to be rare even with the movement to less hostile formulations. This may be attributed to controls and quality elements not generally known or discussed in the industry.Therefore, to explore and understand current industry practices, surveys were conducted which focused on three key areas: raw material controls, finished product quality and process hygiene.


Surveys were conducted in 2010 by the Consumer Specialty Product Association’s Microbiology subcommittee of the Cleaning Products Division. The subcommittee developed focused questionnaires of 10-12 directed questions for the specific topics: raw material testing, finished product testing and manufacturing hygiene. These surveys were distributed to major North American and European manufacturers of household and commercial products. The responses were collected, collated, summarized and are the subject of this article.

Responses were obtained from the U.S. and Western European manufacturers with 13 sets of surveys completed and returned.

Raw Materials

Responses indicated a high frequency of testing of raw materials and finished products, focused largely on perceived risk for microbial contamination and driven by factors such as history of contamination, water content, performance in susceptibility testing and potential risk to consumers. For raw materials, some accept supplier certificates of analysis for microbiological quality but virtually all take direct responsibility for finished product quality. Variation in microbiological limits and methodology were reported (Tables 1 and 2, respectively).

The majority of the respondents set microbial limits at 100 or 1000cfu/g or ml. Methods included plate counts, the most frequently reported, as well as enrichment methods and in a few cases, rapid methods. A variety of general and selective media were reportedly used. For microbial limits, respondents were asked:

• If raw materials or finished products are tested against a specification for total count, what are the specific numerical limits?

Microbes of specific significance were identified for potential pathogens such as Staphylococcus aureus and Salmonella spp. as well as those likely to negatively affect product esthetics or functionality such as Burkholderia spp. or molds.

For methodology, respondents were asked:

• If raw materials are tested for microbial contamination, what protocols are used? The same question was asked for finished products.Responses are summarized in Table 2.

Some respondents reported that products that do not meet microbial quality parameters can be reworked (treated) to eliminate the microbial contamination. These findings often provoke more frequent testing of raw materials and finished products. In addition, microbiological testing of the manufacturing process/environment may be implemented to determine and mitigate the root cause of the contamination.

Process Hygiene

The survey responses indicate that many manufacturers/suppliers within the household products and related industries have validated cleaning/sanitization processes. Even though the methods vary, there clearly is a general understanding of the importance of manufacturing “plant” hygiene on product quality. One aspect of a hygiene program, such as continuous microbiological monitoring of the process equipment, seems to be well understood and is generally utilized for assessing microbiological hygiene within the manufacturing environment.

Questions were included to assess the current state of process cleaning and sanitization (C&S) practices within the manufacturing facility. The respondents indicated that the majority of manufacturers understand the importance of both cleaning and sanitization. The main focus of C&S appears to be on the mixing and filling processes.Of the 13 company responses, 12 indicated some level of cleaning of the filling line equipment and flexible hoses, while 13 indicated sanitization of this equipment.Refer to Table 3 for a list and comparison of cleaning and sanitization locations.

The participants were queried on whether their current cleaning and sanitization practicesare validated and documented. Of the 13 respondents, 85% indicated they are following validated protocols for cleaning and/or sanitization. Routine documentation logs were maintained by 100% of the respondents, however, a smaller percentage (46%) of the responses indicated the use of other forms of documentation, such as operator checklists, recordbooks, or some form of electronic databases. Despite the focus on validating cleaning/sanitization processes, the industry metrics for determining effectiveness varied. Some companies use surface swabs to verify the microbiological quality of the production surfaces following C&S. Companies using surface swabs may or may not apply an acceptance criteria, such as < 25 CFU/cm2. The metric used most frequently to assess cleaning, as indicated by the highest percentage of responses (38%), is visual inspection of the process.

Other more analytical methods are employed by a lower percentage of respondents: conductivity (23%), foam tests (15%), grease test (8%) and TOC (8%). Others indicated they did not perform verification following cleaning/santization activities. Table 4 summarizes validation activities currently being performed around cleaning and/or sanitization processes.

A question to understand the consumer products industry’s consideration of plant design and maintenance in addressing hygiene was asked:

• Does your facility consider hygiene and sanitization during the design and/or maintenance of manufacturing buildings, facilities and processes?

The majority of the respondents (85%) responded yes. The industry seems to be well aware of hygienic design principles but continues to struggle with the engineering designs of legacy manufacturing facilities. When considering sanitary design for the manufacturing of consumer product, the majority of respondents have considered the following: slope of process lines, material of construction of process lines, minimization of dead-legs within the process, clean-in-place systems, air handling systems and water quality. In addition, the following types of equipment are considered/ assessed: pumps, gaskets, piping, piping connections, valves, and hoses. Table 5 summarizes design and maintenance considerations among the respondents.

Lastly, to gain an understanding of continuous monitoring practices in the manufacturing environment, participants were asked:

• Does your company perform continuous monitoring of the manufacturing environment and/or equipment, in regards to microbiological hygiene?

The majority (77%) of the respondents perform microbiological monitoring.Even though a large number of responding companies indicated they use continuous monitoring as a tool for measuring micro- biological hygiene within their processes, the methods for selecting sampling locations as well as the sampling locations vary. A summary of the methods employed to determine sampling locations and for current sampling locations considered are provided in Tables 6 and 7, respectively.

The microbiological method used for continuous monitoring is most frequently the traditional surface swab method (85%) for assessing equipment surfaces. A smaller percentage relied on testing the final rinse water (46%) or using direct contact plates, such as Rodac (15%). The media of choice for microbial recovery during continuous monitoring was Trypticase Soy Agar (62%).

A majority of respondents (77%) assess the microbiological quality of water by testing process water. A considerably lower number of companies are testing either rinse water (38%) or reuse water (15%). The microbiological media used for testing of water revealed that approximately half (48%) of the respondents used TSA, while the other half (48%) reported using R2A.


Considering the remarkable versatility of microbes to survive if not flourish in a surprising range of environments,14 concerns and necessary controls reported in these surveys should come as no surprise. Elements of specific focus reported here include quality of raw materials and products, and systems hygiene driven by concerns such as consumer risk, history of contamination and preservation status. In many cases, suppliers provide raw material testing and risk assessments. Specifications and microbiological methods for both raw materials and finished products vary greatly between responses and include a wider range of specified microbial limits than those traditionally specified for cosmetics and drugs. Objectionable microbes include both potential pathogens and those that can compromise product acceptability and functionality. Treatment or rework of raw materials and finished products is practiced by some.

The findings of this study revealed that the household and institutional products industry has a sound understanding of the need and significance of microbiological quality. This industry invests in the same efforts of raw material and finished product control as industries whose microbiological quality issues, standards and practices are better known.

In 2003, the Personal Care Products Council (formerly the Cosmetic Fragrance and Toiletry Association) microbiology committee reported results from a survey of member companies regarding preservative effectiveness testing (PET) practices.15 It found PET to be common among all cosmetic companies. A preceding survey (data not presented) conducted by the CSPA microbiology subcommittee among a smaller number of household and institutional product companies, many of which were respondents in the surveys reported here, also found a substantial number conducting testing to qualify product preservative systems. These PET studies are typically executed with standard microbial isolates as well as microbial isolates unique to products and manufacturing systems.

It is clear that microbiologically relevant testing and quality efforts are a common and effective practice in the household and institutional products industry. Such protocols apparently have been developed in isolation and therefore vary considerably across the industry. By contrast, manufacturers of foods, drugs and cosmetics are heavily invested in microbial quality and enjoy a substantial level of guidance by the industries’ respective guidelines. Both as guidance for new entrants to the household and commercial markets and to facilitate sharing of knowledge within this industry, development of unified general standards guidance would be of great utility. Similar efforts have greatly served the food, drug and cosmetic industries and this will be the objective of CSPA microbiology subcommittee in coming months.

More Information:Phil Geis, PhD,The Procter & Gamble Co.; Email: geis.pa@pg.com



1. Jay, M.J., Loessner, M.J. and Golden, D.A., 2005, Modern Food Microbiology, 7th Edition. Food Science Text Series. p. 751.

2. Hugo, W.B. and Russell, E.D. (ed’s) 1977 Pharmaceutical Microbiology, Blackwell Scientific Publications, pp. 479.

3. Geis, P.A. (ed). 2006. Cosmetic Microbiology: A Practical Handbook 2nd Edition. Taylor & Francis, pp. 295.

4. U.S. FDA enforcement reports:


5. European enforcement reports:


6. Beadle, I.R. and Verran, O. 1999. The survival and growth of an environmental Klebsiella isolate in detergent solutions. J. Appl. Micro. 87: 764–769.

7. Tirodkar, R.B. and Menon, A.B. 1983. Microbial Spoilage of Water Based Paints. Journal of the Colour Society, July/Sept: 10-15.

8. http://www.cpsc.gov/cpscpub/prerel/prhtm l00/00001.htm

9. http://www.cpsc.gov/cpscpub/prerel/pr html95/95071.html

10. Ehrenkranz, N.J, Bolyard, E.A., Wiener, M. and Cleary, T.J. 1980. Antibiotic-sensitive Serratia marcescens infections complicating cardiopulmonary operations: contaminated disinfectant as reservoir. The Lancet 316:1289-1292

11. Weber, D.J., Rutala, W.A. and Sickbert-Bennett, E.E. 2007. Outbreaks Associated with Contaminated Antiseptics and Disinfectants. Antimic. Agents Chemother. 51:4217-4224.

12. http://www.arb.ca.gov/consprod/regs/ regs.htm

13. http://www.aboutcleaningproducts. com/

14. Trotsenko, Y.A. and Khmelenina, V.N. 2002. Biology of extremophilic and extremotolerant methanotrophs.Archiv. Microbiol. 177:123-131.

15. The Cosmetic, Toiletry, Fragrance Association. 2003. CTFA preservative challenge and stability testing