College science professor explains the risks to silica exposure

Silica, or silicon dioxide (SiO2), is one of the most abundant materials on earth. Found naturally in various organisms as well in sand particles in many parts of the world, it is also manufactured synthetically for various purposes including crystals, silica gels and in the food industry. With so much use of silica in our daily lives, scientists have wondered about health benefits as well as the potential harmful effects of silica. One of the hypothesized harmful effects of silica is that it may cause cancer in human beings. Let us examine some of the scientific research conducted to obtain an answer to the question.

Diatomaceous earth

The question of the potentially carcinogenic quality of silica becomes even more relevant when we particularly consider the food-grade uses of a substance known as diatomaceous earth. It is composed of ancient aquatic organisms, now fossilized, whose skeletons were primarily composed of silica. Commonly appearing as a white power, diatomaceous earth is a kind of naturally-occurring soft siliceous sedimentary rock. Its highly porous nature causes it to have low density and an abrasive feel.

Although diatomaceous earth has many industrial applications such as the composition of explosives and packaging, what we are concerned with here is how it impacts human beings. And there are various ways it can do that. The most important use of diatomaceous earth, for our purposes, is in filtering drinking water. Its chemical and physical composition enables it to stop very fine particles that can easily pass through cloths and other filtration processes. This is why it’s so popular in the filtration of drinking water and other beverages such as beer or wine.

Diatomaceous earth can also have an impact on humans due to its use as a natural abrasive in toothpastes and some facial scrubs. It is also approved by FDA for its use in agriculture and livestock. You can click here to purchase natural diatomaceous earth.

Crystalline and amorphous silica

To understand the role of silica in causing cancer, we first need to distinguish between two naturally-occurring forms of silica: crystalline and amorphous. Although both kinds are formed due to reaction of silicon and oxygen, differing environmental conditions under which they’re formed leads to varying structures. The one simple feature through which we can distinguish between the two forms is through observing their structures. Crystalline silica is ordered and structured. You can clearly observe repeating patterns in its structure, as is the case with other crystals. Amorphous silica is significantly different in that it is not organized in repeating patterns.

Research suggests that prolonged exposures to the crystalline forms of silica may lead to cancer. Before moving on to the specifics and merits of these studies, we need to consider how humans can come into contact with crystalline silica. The persons who are most at risk to silica exposures are industrial workers who may regularly inhale silica dust due to the nature of their work. Some of these examples include sand blasters, metal workers, and ceramics workers. Diatomaceous earth, although composed primarily of amorphous silica, may also contain small amounts of crystalline silica.

Scientific studies on silica and cancer

There have been various scientific studies on how silica can lead to cancer. Most of these studies link exposures to crystalline silica and the development of lung cancer, particularly among industrial workers. Let us examine some of these studies and try to examine whether it is really possible.

The effects on animals

Various experiments were conducted to assess the carcinogenic effects of crystalline silica in animals. In one such experiment, rats were injected with crystalline silica to examine its effects. It was later proved through observations that crystalline silica does, in fact, causes cancer in rats. When similar experiments were conducted on other animals such as mice and hamsters, no such effects were reported. [1]

These experiments point to the role of the nature of the hosts. In simple terms, it means that the carcinogenic effect of crystalline silica in rats does not prove that the same would be true in human beings as well.

The effects on industrial workers

Some studies suggest that prolonged exposure to silica may lead to lung cancer and other pulmonary problems in industrial workers. These studies base their hypotheses on the observations of an increased rate of reported cancer cases among the industrial workers regularly exposed to crystalline silica. A study conducted among the industrial workers in California explores this question. The subjects of the study were 2,342 diatomaceous earth mining and processing workers. These workers, due to the nature of their job, were regularly exposed to crystalline silica.

According to the results of the research, those workers with prolonged exposure to breathable crystalline silica dust were at a greater risk of developing pulmonary cancer than an average person. The researchers observed that the weaknesses in current occupational health standards can lead to even greater risks of cancer in the future. [2]

However, another study criticizes the findings of the aforementioned research and other reports about lung cancer in industrial workers. According to the study, there are various significant shortcomings in those reports. The data is difficult to interpret since it ignores the role of other carcinogenic agents such as tobacco smoking and other potential carcinogens related to the occupation. The study suggests that a clear-cut causal relationship between crystalline silica and pulmonary cancer in humans cannot be established. [3]

What does it all mean?

The disagreements within the scientific community and the complex jargon of the academic studies can easily confuse all of us in search for answers. Does mean that there is no definitive relationship between silica and silica products and cancer? What are we to deduce?

The problem can be simplified by breaking it down. Are you an industrial worker with prolonged exposure to crystalline silica? If yes, then there is sufficient evidence to suggest that it may increase the risk of lung cancer, although no definitive proof exists yet.

However, most of other domestic consumers of silica-based products such as diatomaceous earth need not worry because no such evidence exists that may prove that silica causes cancer.

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