From swim caps to condoms, from chewing gum to trusty medical gloves, latex has a wide variety of uses and applications in modern times. So many, in fact, that we may take it for granted. But did you know that this ubiquitous rubbery material begins as a natural fluid that comes from plants?
What is latex, and where does it come from?
One in ten of every plant species (all of which are called angiosperms) has a specially adapted defence mechanism, to protect the health of the plant. When under attack from herbivorous insects, these plants secrete a milky liquid which stiffens and sets when exposed to the oxygen in the air, trapping or killing the invading creatures. Because of its coagulative properties, this fluid has proven a useful source of a variety of materials we call Latex.
A brief history of natural rubber
The history of natural rubber begins thousands of years ago, with the indigenous people of Central America. The earliest examples of natural rubber being used by humans are from the Olmecs, an early civilisation in Mesoamerica. They cultivated the natural materials for use as balls in ancient games, similar to racquetball. Later in history, Aztec and Mayan cultures would use the same material to create bowls and vessels. They also used latex to make fabrics and clothing waterproof.
Closer to home, in western society, natural rubbers were first scientifically identified by François Fresneau in a 1751 paper. Twenty years later, English scientist Joseph Priestley identified a now universal use for the materials – as pencil erasers. The act of applying friction to paper with the material is how the term ‘rubber’ became common.
By the 1900s, natural rubber materials had a wide range of applications. It was frequently used in automotive manufacturing, with car tyres comprising a high proportion of natural rubber use in industry. What’s more, latex found its use in many household items including gloves, toy balloons, pencil erasers and rubber bands. For some time, it was used in the textiles industry for its stretchy, elastic properties. While some clothes today are made of latex, it’s been superseded by alternatives. These alternatives are not damaged by oils, sweat, or sunlight unlike latex.
In any case, millennia after its initial discovery and cultivation by humans in Mesoamerica, natural rubber still has an important part to play in modern society.
Rubber Latex
How does a plant’s secretion become a useful commodity? Rubber latex, in its original fluidic form, is tapped from rubber trees. Like any other important crop, the rubber trees need just the right conditions to give rise to the perfect raw material for human cultivation. These trees need to grow within twenty to thirty-four degrees Celsius. What’s more, they strive with humidity levels of approximately eighty percent, and strong sunlight with little wind. For this reason, the majority of raw material is harvested from trees planted and grown in Malaysia, Indonesia, and Thailand.
Farmers literally tap the trees with special tools to emulate attacking insects. This triggers the tree’s defence mechanism. In turn, this causes natural rubber to flow from channels on the inner layer of the tree’s bark. Harvesters are careful to tap the tree in just the right places. Couple this with the appropriate depth, harvesters work hard not to damage the tree. A poorly executed harvest can stop a tree from growing for good. This can make it unsuitable for yielding rubber.
Once collected, the farmers have to work quickly before the liquid hardens. The fluid is moved to coagulation tanks or into air-tight vessels to slow the setting process. The fluid is then processed into a concentrate for manufacture of dipped rubber products. Alternatively, it is carefully hardened in a clean, controlled, environment with the use of formic acid. The set material can then be treated into higher-grade, block rubbers for different industrial uses.
Health and allergies
Natural rubber sensitivities are fairly common, with up to eight percent of the general population having an allergy. An allergy can vary in level of seriousness. It can cause anything from mild irritation to anaphylaxis, and is termed as either Type I or Type IV.
Type I is the most serious and uncommon expression of an allergy to natural rubber. It can potentially be life threatening, eliciting a state of anaphylaxis. Anaphylaxis is the body’s defensive state of shock. It is similar to those occurring in people with a hypersensitivity to bee stings. It can result in an itchy rash, swelling of the throat or tongue, or vomiting.
A Type IV allergy is known as allergic contact dermatitis. This causes a rash on the skin, sometimes accompanied by oozing or blistering. Thankfully though, a reaction of this kind will not cause anaphylaxis.
Intolerances of natural rubbers can be tested from a young age using skin patch tests. Another option is to test a person’s blood to see if the patient’s body produces specific antibodies.
The impact of latex on the environment
As society becomes more conscious of its effect on the environment and the future state of the planet, there’s a valid question to be asked. Does latex has any negative effects? In short, yes it does.
Natural rubbers, being entirely naturally produced, in principle, are not harmful to the environment. In its primitive form, the raw material tapped from trees can be broken down by bacteria. Significantly, at this stage it causes no harm.However, once processed, latex is not without its problems from an environmental perspective. When processed for industrial use, the natural and safe material has to be treated with various chemicals. This includes ammonia to preserve and protect against decomposition. Once processed, bacteria can’t break down the material. With this in mind, it can cause harm to the environment if not properly disposed of.
Human behaviour is somewhat to blame for the environmental impact of natural rubber. Take a common use for example, condoms; the average condom weighs a tenth of an ounce. However, the overall weight of used condoms thrown away is nearly three million pounds! That’s nearly 1,500 tons. However, in reality it’s likely that the health industry is more careful about how they dispose of tons of medical latex gloves, rather than condoms.
While somewhat usurped by the invention and modern manufacture of synthetic rubbers, it’s safe to say that naturally-sourced rubber isn’t going anywhere. With a decline in certain industries, like textiles and fashion, usage is down. However, for some applications latex is still king. Take for instance a trusty pair of medical gloves for health related applications, or condoms for common usage. Rubber will always bounce back!
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