By Dr. Mercola
Little, yellow rubber ducks often adorn toddler bath time and were popularized when Sesame Street released their classic ode to the duck in February 1970.1 Sung by Sesame Street character Ernie, with the voice of Jim Henderson, the song became a surprise mainstream hit, reaching No.16 on the Billboard Hot 100 in September of the same year and nearly winning a Grammy the following year.
The rise in popularity of the little yellow duck could not have been predicted. In the ensuing years, these little plasticized toys became a staple in toddler bath-time and have gone on to be used in a benefit for the Special Olympics in Illinois when 60,000 of the tiny toys were released into the Chicago River.2
Canada used a six-story high version of an inflatable yellow duck in their Canada Day celebrations in 2017, requiring 2.5 hours to inflate, eight to 10 people to manage it, a crane to move it3 and costing $120,000 to rent for two months.4
The first rubber toys appeared in the late 1800s5 and were cast solid, intended as chew toys. By the 1940s, the toy had developed into an iconic figure with a bright orange bill. Today, research has confirmed what many parents suspected — tthe inside of these toys contain loads of bacterial and fungi growth.6
Throw Out the Duck With the Bathwater
The study was conducted by the Swiss Federal Institute of Aquatic Science and Technology and the University of Illinois. The researchers gathered 19 bath toys used under real-life conditions, analyzing them for notable biofilms on their inner surface.7 This study followed another completed several decades earlier, which suggested bath toys facilitated microbial growth, specifically the proliferation of pathogenic organisms such as pseudomonas or enterococcus.
In the late 1990s a multidrug-resistant outbreak of pseudomonas at a children’s hospital was linked to shared bath toys.8 This study made the first connection between bath toys and infections, as the pseudomonas was only present in the bath toys and not detectable in the water itself. The researchers’ goals in the present study were to provide a comprehensive characterization of the bacterial growth inside real toys and to establish a better understanding of the factors driving the development of these bacteria and fungi.9
To accomplish this, they first studied biofilm extracted from bath toys used in real life conditions and compared it against appearance and microbial abundance in new, identical toys used under controlled conditions, simulating use in clean and dirty bathwater. The study, billed as one of the first in-depth scientific examinations of its kind, revealed a strikingly high volume and variety of bacteria and fungus inside the bath toys.10 The bacteria found included Legionella and pseudomonas.11
Fungal populations present in the bath toys were also analyzed using sequencing technology. The results revealed the most flexible toys contained the most diverse microbial growth.12 Specifically, dissection of the toys revealed between 5 million and 75 million bacterial cells per square centimeter.13 Researchers also found fungi species in 60 percent of the real bath toys and in all of the toys tested under controlled conditions in dirty water.
The exact type of bacteria or fungi varied between households but, overall, 80 percent included Legionella and pseudomonas. Study author Frederik Hammes, Ph.D., of the department of environmental microbiology at the Swiss Federal Institute, commented,14 “Moldy bath toys are widely discussed in online forums and blogs, but they have received little scientific attention to date.”
Lead author and microbiologist Lisa Neu commented on the differences found between different types of bath toys saying,15 “We’ve found very big differences between different bath animals. One of the reasons was the material, because it releases carbon that can serve as food for the bacteria.”
Nutrients in Water and Plastic Feed Bacteria and Fungi
According to authors of the featured study,16 one source of microorganisms in the biofilm of bath toys is tap water, which differs substantially between locations. Complex microbial communities often contain opportunistic pathogens such a pseudomonas and Legionella. Tap water does not contain nutrients contributing to microbial growth. The human microbiome and environmental contamination, however, does.
Nutrient sources for these bacteria may originate from personal care products such as soaps and shampoos, and from human waste transferred from the body to the bathwater.17 Furthermore, the flexible polymeric materials used to produce rubber ducks are known to release considerable amounts of organic carbon compounds, favoring microbial growth.
These compounds are not from primary polymers but rather plasticizers and stabilizers added to improve the flexibility of the product.18 The flexible synthetic materials, which mostly consist of polyvinyl chloride (PVC) or silicone rubber, tend to absorb organic matter and facilitate growth.
Although fresh urine from a healthy individual does not contain bacteria, it does contribute carbon and nitrogen, nutrients necessary for bacterial growth.19 PVC not only produces nutrients for the growth of bacteria and fungus but also provides a stratum on which fungus may grow and degrade the material.20 Hammes commented on the contribution to microbial growth plasticizers make:21
“All these soft plastic materials have softeners called plasticizers in them to make them flexible. (The plasticizers) migrate out of the plastic into the water. The bacteria like to eat them. It just gives them a nice amount of food to grow.”
Exposure May Increase Risk of Childhood Infections
Researchers from the featured study do emphasize exposure to a reasonable amount of bacteria can help your immune system. While it may seem counterintuitive based on the number of advertising campaigns selling products promising to kill 99.9 percent of germs on surfaces, the hygiene hypothesis proposed in 1989 by British epidemiologist David Strachan22 suggests we may be living in an environment too clean for our own good.23
Researchers have discovered children growing up in less clean environments have a lower risk of developing sensitivities to substances like pollen and dog dander than those who grow up in exceptionally clean homes. Dr. Samuel Friedlander, allergist at the University Hospitals Case Medical Center in Cleveland, explains it this way:24
“I believe that the immune system is like an army. So, if the army doesn’t have something to fight like microbes, it’s going to fight things like allergens in many cases. People [who] live on farms are exposed to more microbes and as a result the immune system tries to fight those bugs and then, in turn, the body doesn’t have to fight allergens.”
It is important to remember that no matter how diligently you clean your home, you’ll never completely eliminate bacterial growth on surfaces. On the other hand, maintaining good standards of personal hygiene may help you avoid acquiring infections and prevent the spread of infections to others.
The scientists who published the featured study point out while certain amounts of bacteria help strengthen a child’s immune system, the same bacteria can also lead to eye, ear and intestinal infections, especially in those who are immunocompromised or very young children.25 When water is squirted from bath toys directly into the eye or ear it may increase the risk of infection.
Plasticizers Feed Bacteria and More
Plasticizers are found in many different products, not just children’s toys. They are chemicals used to increase the flexibility and durability of plastic polymers. Your shower curtain, food packaging, vinyl gloves and even household cleaners and personal care products contain phthalates (plasticizers).
While rubber duck toys release carbon to feed bacterial growth, they also contain phthalates, industrial-strength hormone disruptors which find their way into toddlers’ mouths. Plasticizers disrupt the endocrine system, potentially triggering testicular cancer, low sperm count, genital malformations and infertility. While the amount of phthalates ingested from a rubber duck during bath time may be minimal, the unfortunate reality is these chemicals are in many other everyday products surrounding you and your family as well.
For instance, in an evaluation of dietary habits and urine metabolites of 9,000 participants ages 6 and older,26 researchers discovered the majority of people who ate fast food had a greater excretion of phthalates than those who did not consume fast food. The study analyzed exposure and not the potential negative health effects, but they found a dose-related relationship between the amount of fast food participants were eating and the amount of phthalates to which they were exposed.
In a study published by the American Chemical Society (ACS), researchers found pregnant women exposed to phthalates found in food packaging, personal care items and other everyday products, had an increased risk of miscarriage between five and 13 weeks of pregnancy.27 Further studies demonstrate exposure to phthalates during pregnancy may increase the risk of adversely affecting the masculinization of male genitals in your baby.28
Exposure has also been associated with impaired neurodevelopment, respiratory problems and altered genital development.29 In the past, studies have largely focused on absorption through direct contact with the skin, but more recent models have predicted a significant transdermal uptake directly from ambient air. In other words, the more you can remove plastics and products containing phthalates from your immediate environment, the lower your risk of suffering health effects associated with exposure.
There’s more than one reason to throw out the rubber duck with the bathwater. Exchange your plastic and rubber bath toys with washable cloth toys, using the dryer on high heat to kill the remaining bacteria and mold, and consider tub toys without holes to reduce the risk of growth. In all cases, keep a watchful eye and keep the toys out of your baby’s mouth.
Your Home Is Likely Teeming With Bacteria and It May Not Be Bad
The featured study received funding from the Swiss government as part of a broader analysis of bacteria growing on household objects. Last year, German researchers determined kitchen sponges from 14 private homes carried more than 350 different species of bacteria.30
The study also found microwaving sponges could make the bacteria worse since the strongest pathogenic bacteria tended to survive and thrive. In an interview with The New York Times, Markus Egert, microbiologist at Furtwangen University in Germany commented on the amount of bacteria found on sponges, saying,31 “That’s the same density of bacteria you can find in human stool samples. There are probably no other places on Earth with such high bacterial densities.”
Washing machines are also an ideal breeding ground for bacteria.32 Charles Gerba, professor of microbiology at the University of Arizona, has spent years researching the germs that grow and thrive in your washing machine. Gerba says your underwear is the major problem as they often carry fecal material into the machines. Fecal material may carry a number of different bacteria, including rotavirus, E. coli, salmonella and hepatitis A virus. Gerba says:33
“If you wash a load of just underwear, there will be about 100 million E. coli in the wash water, and they can be transmitted to the next load of laundry. There’s about a tenth of a gram of poop in the average pair of underwear.”
Cellphones are another culprit, sometimes carrying 10 times more bacteria than most toilet seats.34 Your computer keyboard may also host potentially harmful bacteria as found by a study commissioned by a consumer advocacy group. Evaluation revealed at least one keyboard had five times the level of germs than may be found on a toilet seat.35
In a study from the University of Arizona, researchers found the average desktop had 400 times more bacteria than the average toilet seat.36 Microbial growth on toilet seats has been commonly used by many researchers to compare bacterial growth on other items. However, after publication of the featured study, this comparison may change to a child’s bath-time rubber duck.