Natural rubber, not so natural

A lot of baby products are made of natural rubber, such as bottle teats, pacifiers and baby toys. Many people assume that natural rubber is completely natural and environmentally friendly, but is it? How sustainable is its production and what factors affect its environmental impact? And what role does silicone play in all of this?

Natural rubber and additives

Natural rubber (latex) is a natural product obtained as sap from the rubber tree. In its raw form, however, latex is not suitable for durable consumer products. To make natural rubber usable for applications such as pacifiers and bottle teats, the material undergoes a process called rubber compounding and vulcanization. [1-3]

Depending on the desired end product and manufacturing process, different categories of substances may be used, such as:

Vulcanizing agents (e.g., sulfur), to make the rubber elastic and strong
Stabilizers, to limit aging caused by oxygen and UV light
Fillers, to influence mechanical properties
Colorants, if a specific color is required

Not all of these substances are used in every product; the exact composition varies by manufacturer and application. For products intended for food or oral contact, strict legal requirements apply, meaning that only approved substances may be used within established limits.

Natural rubber and impact on the environment

Natural rubber is a natural product, but that does not automatically mean its production has no impact. To make natural rubber suitable for products such as pacifiers and bottle teats, the material is processed and combined with additives that must comply with strict safety regulations.

In addition, the production of natural rubber, depending on its origin and manufacturing methods, can involve environmental and social considerations. [4-8] In some regions, the expansion of rubber plantations is linked to changes in land use and potential effects on biodiversity. There are also internationally recognized challenges regarding working and living conditions in parts of the natural rubber sector.

Precisely because these concerns exist, initiatives and certification programs have been developed that focus on more sustainable production and improved working conditions throughout the natural rubber supply chain.

Natural rubber – Gentle materiaal

As mentioned above, natural rubber may contain chemical additives, and like many materials, its production can have environmental effects. If you choose to use natural rubber products, make sure to read the instructions carefully and keep the following points in mind:

Natural rubber should be replaced every four to six weeks. For silicone, replacement is typically every six weeks.
Heat sources (such as sunlight, sterilization, or heating) can cause natural rubber to break down, soften, become sticky, dry out, discolor or deform.
Sucking can change the shape of natural rubber; it may also expand slightly and develop a mild scent.
Natural rubber contains (safe) softeners. Both natural rubber and silicone are free of BPA and PVC. BPA has been banned from baby products since 2011 and PVC is only used in plastics.
Some children may develop an allergic reaction to the proteins naturally present in rubber.
Natural rubber can have a mild taste, which may lead some children to refuse it.

Silicone vs. natural rubber

At Difrax, we consciously choose silicone for our baby products, as we believe that natural rubber is not necessarily more environmentally friendly or as ‘natural’ as its name may suggest. We consider silicone a cleaner option in terms of durability and hygiene, while acknowledging that all materials have environmental considerations.

The advantages of silicone:

Odorless and tasteless: Silicone is odorless and tasteless. Latex may have a rubber-like smell and taste, which some children may be sensitive to or may prefer to avoid.
Hygiene: Looking at material properties, silicone is easier to clean due to its smooth surface. [1-3] Both silicone and rubber can be cleaned safely when used and maintained according to applicable standards. Surface smoothness and stability influence ease of cleaning. Silicone is a stable synthetic material that retains a smooth surface under repeated cleaning, while natural rubber, as a biological material, can change over time due to heat and oxidation, which may affect its surface and cleanability.
Cracks less quickly: Silicone is firmer and therefore cracks less quickly. It can put more pressure on the palate and the increasingly strong jaw of your baby and lasts longer, which makes it more durable. Silicone is not sensitive to deformation caused by sucking.
Allergy-free: Silicone is allergy-free, whereas your child may be allergic to rubber.
Weatherproof: Silicone is resistant to sunlight, moisture, heat and cold. When exposed to heat and UV light, natural rubber can easily break, soften, get sticky, dry out, discolor and deform.

As babies grow, their sucking needs change, which is why pacifiers come in different sizes with firmer teats and larger shields. But is age the only factor? Read also our guide when to change pacifier size.

Interested in the details about this article? See the supporting sources below.

1. ScienceDirect Topics – Rubber compounding.
https://www.sciencedirect.com/topics/materials-science/rubber-compounding

2. Rubber compounding & additives.
https://www.academia.edu/10112357/Rubber_Additives_Compounding_Ingredients

3. Rubber compounding ingredients.
https://www.rubberlix.com/rubber-compounding-ingredients/

4. Wang, Y., et al. (2023). High-resolution maps show that rubber causes substantial deforestation.
https://pmc.ncbi.nlm.nih.gov/articles/PMC10632130/

5. International Institute for Applied Systems Analysis (IIASA). (2023). Rubber trees and deforestation: quantifying the impact of rubber production on tropical forests.
https://iiasa.ac.at/news/nov-2023/rubber-trees-and-deforestation-quantifying-impact-of-rubber-production-on-tropical

6. WWF Asia Pacific. Multi-actor rubber partnerships and forest impact.
https://asiapacific.panda.org/our_work/forests/multi_actor_rubber_partnerships/

7. International Labour Organization (ILO). Agriculture, plantations and rural sectors.
https://www.ilo.org/global/industries-and-sectors/agriculture-plantations-other-rural-sectors/lang--en/index.htm

8. Fair Rubber Association. Mission and background.
https://www.fairrubber.org/

9. TI Vieira et al. Surface analysis of latex and silicone pacifier nipples (qualitative surface differences).
https://rsdjournal.org/rsd/article/view/23074

10. LC da Silveira et al. Biofilm formation on silicone vs latex pacifier nipples (SEM evidence of surface roughness).
https://oss.jocpd.com/files/article/20220812-1019/pdf/JOCPD.33.3.235.pdf

11. VMI Plastic – Silicone pacifiers non-porous and easier to clean than latex.
https://www.vmi-plastic.com/latex-pacifiers-vs-silicone-pacifiers_-key-differences/