Author: Zhao Guangna
Decoration pollution, formaldehyde exceeding the standard is the culprit that causes leukemia, which seems to be common sense that everyone knows subconsciously, and "cases" of leukemia due to formaldehyde abound, which further supports their own judgment.
In January 2018, Mr. Wang, an Employee of Alibaba, did an entry physical examination, and the report showed that the physical indicators were normal, and on May 8, he moved into a house managed freely, and for about 2 months, Mr. Wang felt unwell and was diagnosed with leukemia, and died on the 3rd day of admission;
In 2014, Fang mou bought an Audi car, the car was hot and pungent, and he did not care, and as a result, he was found to have acute myeloid leukemia more than a year later, and Fang died in 2017. In March 2019, a public account published an article titled "They all bought Audi cars, they all got leukemia", and six owners who claimed to buy and drive Audi cars or the owners' families suffered from leukemia, and four of the six people were acute myeloid leukemia.
These two events have caused a lot of noise on the Internet and have attracted widespread attention from many media and car friends. Of course, whether it is Ali employees or Audi car owners, their families have resorted to the law, but the law does not support their claims. Because in all cases like that, even if the air quality in the house and the car has been shown to be problematic, it is important and difficult to prove the causal relationship between quality and leukemia.
Relationship between formaldehyde and leukemia
We sympathize with the plight of these people. But from a purely evidence-based point of view, will formaldehyde cause cancer in the end, and is it related to leukemia?
Let's first understand formaldehyde, formaldehyde (FA) is a colorless, pungent, highly flammable gas, is a highly active compound, widely used in construction, textile, paper industry, synthetic wood panels, insulation materials, paints, plastics, glue and cosmetics industry, in the photochemical smoke, and even fruits are also found. As a result, more and more people are exposed to formaldehyde.
The International Center for Research on Cancer (IARC), an agency of the World Health Organization, has identified formaldehyde as a class of carcinogens. What is a class of carcinogens? The registration of carcinogens is not equivalent to the intensity of carcinogens, but the level of evidence of carcinogens, such as a class of carcinogens can clearly cause carcinogens; class II carcinogens, carcinogenic in animals, but whether the human body is carcinogenic needs further research; three types of carcinogens have the possibility of carcinogenicity, and it is not certain whether it can cause cancer. This shows that formaldehyde is a clear carcinogen, what kind of cancer can it cause?
The National Cancer Center expert group believes that there is sufficient evidence to prove that formaldehyde causes nasopharyngeal cancer in humans, which is relatively rare in developed countries, and that there is limited evidence that formaldehyde can cause nasal and sinus cancer. Epidemiological investigations have shown that formaldehyde has a clear correlation with the occurrence of nasopharyngeal, pancreatic, skin, prostate, gastric and brain tumors.
What is the relationship between formaldehyde and leukemia?
Hauptmann et al. have conducted a cohort study of 25,619 workers exposed to formaldehyde in the United States that formaldehyde exposure may cause human leukemia, particularly myeloid leukemia, but further research is recommended due to the confounding factors in the investigation.
Later, a cohort study of 11,039 formaldehyde exposure workers exposed to formaldehyde for more than three months in 3 garment workshops found that formaldehyde exposure and myeloid leukemia may be associated, but epidemiological studies have concluded that formaldehyde causes leukemia with strong but insufficient evidence. So IARC believes that there is no completely sufficient evidence to prove a causal link between formaldehyde and leukemia.
What needs to be clear is that these studies are not aimed at the simple situation that the formaldehyde in our house decoration exceeds the standard, but the follow-up study of the workers who are exposed to the formaldehyde exceeding the standard of home decoration on a daily basis, and the formaldehyde exposed to these workers can be much higher than the formaldehyde in our home.
In fact, formaldehyde is "formalin", in the hospital, we will use formalin to soak the body, embalming the body. I do this work every day, I smell formalin every day, and I smell it for more than 30 years. Moving forward, so did my teachers. Some people have done this research and have not found that doctors who spend all day with formalin are more likely to develop leukemia than the average person.
The relationship between contaminant benzene and leukemia was determined
In fact, like other cancers, the onset of leukemia is the result of the superposition of multiple factors, not limited to one factor, mainly including radiation, genetics, viruses and chemical poisons and other factors. Radiation, such as atomic bomb explosions, nuclear power plant explosions, marble used in decoration, etc., the high incidence of Hiroshima leukemia in Nagasaki is related to the radiation of atomic bombs;
The second is heredity, leukemia is not a genetic disease, but the occurrence of leukemia is related to genetic susceptibility, genetic susceptibility refers to different populations, different individuals due to different genetic structures, under the condition of external environment, showing a tendency to suffer from a certain malignant tumor. Due to the different genetic susceptibility of different individuals, some people who are also exposed to specific carcinogens develop tumors, while others do not develop tumors, which is why some people who smoke smoke have cancer and some cannot.
The third is the virus, in many cases of leukemia, there is t lymphocytic leukemia caused by RNA retroviruses, although this condition is relatively rare, but the probability of deterioration is high.
Let's focus on benzene, the fourth pollutant that causes leukemia. Recently, Wu Zhiming, a migrant worker from Jiangxi, is still waiting for the final appraisal results of his occupational disease appraisal, the first two appraisals are "occupational tumors (benzene-induced leukemia)", and more than one person in one factory has been diagnosed with leukemia.
In the decoration pollution, formaldehyde and benzene are the two most common chemicals, exceeding the standard is also the most extensive, the relationship between formaldehyde and leukemia is uncertain, but the relationship between benzene and leukemia is determined. Evidence of benzene-induced leukemia comes mainly from laboratory animal studies and epidemiological studies.
According to the data, through inhalation and intradermal injection of benzene in mice, researchers found that under exposure to benzene in different pathways and concentrations, leukemia in mice can be caused, and the success rate of high concentration benzene induced leukemia is higher than that of the low concentration group. At the same time, epidemiological data suggest that occupational exposure to benzene can lead to the development of benzene leukemia (the lowest exposure dose is 32 to 80 mg/m3).
In recent years, the popularity of decoration in China has made the relationship between non-occupational benzene exposure and leukemia increasingly concerned. Studies have reported that occupants within 3 months of renovation may increase the risk of leukemia.
Carcinogenic concentration and toxicity study of formaldehyde
Any kind of carcinogen, need a certain dose of accumulation to cause cancer, and carcinogenicity is not a few days and months, but long-term exposure to carcinogenic, this is a slow process, not a contact with carcinogens cancer will occur. Formaldehyde is the same, reaching a certain concentration will cause human discomfort, and even lead to disease and cancer.
In the "Indoor Air Quality Standards" promulgated by the state, the formaldehyde content is ≤ 0.1mg/m³, which is greater than this value. In real life, if there is a pregnant woman or a child's living environment, it should generally be less than 0.05mg/m³
1. The concentration and harm of formaldehyde
Below is a cross-reference table of formaldehyde concentrations and hazards.
2. Toxicity study of formaldehyde
The general toxicity of formaldehyde mainly includes the following aspects:
(1) Central nervous system toxicity: Animal experiments have shown that 0.5mg/m3 formaldehyde has direct neurotoxicity in mice. Inhalation of formaldehyde in mice can inhibit learning and memory.
(2) Reproductive system toxicity: infecting male mice with formaldehyde can cause pathological damage to testicular tissue, organ coefficient, sperm survival rate, activity rate and sperm count are reduced, and the malformation rate is increased.
(3) Cardiovascular system toxicity: formaldehyde can interact with peroxides, by promoting the oxidation of low-density lipoproteins, platelet aggregation and the formation of thrombosanes and the formation of atherosclerosis, experiments have confirmed the toxic effect of formaldehyde on the cardiovascular system.
(4) Respiratory toxicity: The toxicology of formaldehyde to respiratory damage shows that formaldehyde has genetic damage to bronchial epithelial cells and lung macrophages. Research such as Fujimaki argues that exposure to low doses of formaldehyde can induce or worsen respiratory inflammation.
(5) Immune system toxicity: Inhaling formaldehyde can cause lipid peroxidation reaction of the mouse immune system, which eventually leads to the destruction of the oxidation balance system in the body's immune tissue and causes immune damage.
The most effective way to reduce formaldehyde pollution - ventilation
Indoor space is closed, air circulation will aggravate the degree of indoor environmental pollution, the most effective way to reduce formaldehyde is ventilation, often open windows for ventilation, accelerate the speed of air flow, can effectively accelerate the volatilization speed of harmful gases such as indoor formaldehyde and benzene, the faster the air circulation speed, the faster the volatilization speed of harmful gases.
The longer the indoor window opening time, the lower the concentration of harmful gases such as formaldehyde and benzene, it is best to open the window 24 hours a day, once there are several hours of airtight, the slow release of formaldehyde will increase the environmental concentration. In addition, it should also be noted that in winter, the sister has heating, and the indoor long-term closure is not suitable for decoration, which is not conducive to the volatilization of harmful gases. Renovations should be carried out in the spring and summer, when the air circulation is fast.
Professor Ji Xiaolong
Formerly the chief physician and professor of the Department of Pathology of the PLA General Hospital, he is currently the deputy editor-in-chief of the journal Cancer Rehabilitation, the director of the Department of Tumor Biological Therapy, the director of the Department of Pathology, and the director of the Institute of Nanomedicine of the Beijing Armed Police General Hospital.
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