When Does a Cancer-Causing Substance Cause Cancer?

The Concept of “Cancer-Causing”

Carcinogenis the general name for things that cause cancer.

These “things” may be a substance or a lifestyle practice (such as smoking, HPV, sunlight, the hairdressing profession and so on).

The word “carcinogen” comes from “carcinogenesis.” Carcino-genesis means cancer formation. A carcinogen can therefore be described as “cancer-forming.” In Turkish, cancer-causing substances are frequently and incorrectly called “kanserojen”; “kanserojen” is an incorrect expression.

“When” Does It Cause Cancer?

From time to time, claims that certain substances cause cancer or are unhealthy become topics of public debate. Interestingly, such claims seem to be supplied to the media regularly.

The truth is that hundreds of things, natural or artificial, have the potential to cause cancer, and the common feature of these carcinogens is that they trigger cancer depending on dose and duration of exposure .

What Determines Harm: Total Dose and Duration of Exposure

"Dose (intensity) X Duration” is the main determinant of how harmful / toxic something is, making it a fundamental concept of toxicology. However, when humans are involved, other factors beyond “dose x duration” must also be considered. For example, the capacity to repair DNA damage is one of our genetic differences explaining why some people are less affected by carcinogens.

How Is a Substance Determined to Be Carcinogenic?

The International Agency for Research on Cancer (International Agency of Research Cancer-IARC), a subsidiary of the World Health Organization (WHO), is central to claims of carcinogenicity. However, IARC is not the only organization responsible for determining cancer risks from product ingredients or lifestyles, and many countries have authority to take their own national precautions and inform the public.

A summary of the IARC carcinogen list is shown below:

Carcinogen classification is inevitably complex, and IARC’s multilayered recommendations of this kind, combined with conflicts of interest, may move away from the fundamental purpose of risk assessment. For example, prolonged debates have concerned the carcinogenicity of two widely used commercial products, baby powder and the weed killer glyphosate .

For decades, the relationship between applying powder to the groin and women’s ovarian cancer has been debated. In 2010, IARC assessed this relationship as probably carcinogenic to humans . Red meat consumption was placed in a slightly higher category.

The United States National Toxicology Program did not definitively identify talcum (baby) powder as a probable carcinogen. However, the American Cancer Society estimates that the risk is very small and states that conflicting data mean more research is needed.

Some experts have concluded that the actual cause of ovarian cancer is unknown and is likely to involve a combination of many different factors rather than a single cause such as powder use.

Cancer Council Australia similarly stated that “there is insufficient evidence to say definitively that talcum powder use carries an ovarian cancer risk.” Despite these conclusions, Johnson & Johnson (J & J) faces more than 1400 legal claims in the United States on behalf of patients with ovarian cancer. J & J lost two separate cases, one in Alabama (22 February 2016) and another in Missouri (2 May 2016), with damages of 72 million United States dollars and 55 million United States dollars awarded respectively. In one case it lost, the patient with ovarian cancer, for more than 20 years had tried to keep the groin area dry with talcum powder because excess weight had caused chafing there.

These decisions raise concerns about carcinogenic risk being determined according to public perception rather than the overall scientific evidence.

J & J was also perceived as a wealthy international company unfairly targeted simply because it had a large market share and was willing to pay money to support its commercial interests.

Financial interests may be central to long-standing disagreements, such as whether glyphosate is carcinogenic. Glyphosate, used in more than 750 products, is a broad-spectrum herbicide(a substance that destroys plants). In 2015, IARC categorized the chemical as “probably carcinogenic to humans.” In contrast, according to the European Food Safety Authority (EFSA), the United States Environmental Protection Agency, and a joint report by the World Health Organization and United Nations Food and Agriculture Organization, glyphosate is not carcinogenic to humans. These conflicting opinions create considerable confusion.

In May 2016, the European Commission’s Pesticides Committee decided that glyphosate’s authorization would not be withdrawn for another 10 years. It was thought that refusing authorization could harm farmers, food production and consumers. On the other hand, considering IARC’s data, this authorization could be described as “inappropriate” and “unacceptable.” Similarly, many cancer associations, medical groups and governments across the European Union opposed renewal.

How Did This Confusion Arise?

First, IARC and EFSA used different methods to assess evidence. Second, the two organizations took different approaches to classifying chemicals containing glyphosate. Third, scientists claimed that EFSA’s analyses were flawed and biased by studies funded by herbicide manufacturers. Others noted individuals with conflicts in IARC’s evaluation procedures who could improperly influence scientific discussions.

These recent debates on carcinogen classification highlight uncertainty in data, competing interests and difficulties establishing reliable findings. Another important issue is the difficulty of translating carcinogenicity research into appropriate health policies and risk-management recommendations. There is also a strong need for a standardized, internationally accepted method of assessing carcinogens that presents conclusions all stakeholders can easily understand and accept. Until these goals are achieved, defining and regulating carcinogens will remain weakly connected with other cancer prevention measures.

Finally, some causes of cancer are clear while others remain uncertain. It is useful to remember that these debates do not change the fact that smoking, alcohol, obesity, a sedentary lifestyle or HPV cause cancer.

An extensive list of carcinogens can be found in this article .

*

• Do organic fruits and vegetables protect against cancer better than industrially farmed products?
• What are parabens, and why are they used in cosmetics? Where did claims that they cause cancer originate?
• Do mobile phones cause cancer? Science continues to disprove assumptions