Are you afraid of arsenic? How should we view the heavy metal arsenic we come into contact with in our daily life?

Most people's impression of arsenic is probably the arsenic used by Pan Jinlian to poison Wu Dalang. When people talk about the toxicity of a certain substance, they often compare it to arsenic. In fact, arsenic is an element widely distributed in the natural environment. Trace amounts of arsenic can be detected in soil, water, minerals, and plants, and trace amounts of arsenic are also found in normal human tissues.

Arsenic in nature exists in two forms: "inorganic arsenic" and "organic arsenic". The toxicity of organic arsenic can be ignored in many cases, so when we talk about the toxicity of arsenic, we are more concerned about inorganic arsenic.

In daily life, people may ingest arsenic through food, water, air, etc. Studies have shown that an appropriate amount of arsenic helps the synthesis of hemoglobin and can promote human growth and development. Animal experiments have also shown that arsenic deficiency can inhibit growth and cause reproductive abnormalities.

Based on scientific experimental data, the World Health Organization has established a "safe upper limit" for inorganic arsenic for humans: the daily intake should not exceed 2 micrograms per kilogram of body weight. Based on an adult weighing 70 kilograms, the safe upper limit of arsenic intake per person per day is 140 micrograms.

Based on this "safe intake limit", some countries will set limits on the arsenic content of food. For example, China's rice is required to have an inorganic arsenic content of no more than 150 micrograms per kilogram. China's "Standard for Cereal Complementary Foods for Infants and Young Children" (GB10769-2010) stipulates that the upper limit of arsenic content is 300 micrograms per kilogram (for products with added algae). According to this upper limit, a 10-kilogram baby can eat 67 grams of rice flour per day (without excessive intake of arsenic).

In the pharmaceutical industry, whether it is drugs, medical devices or pharmaceutical excipients, there are more stringent control standards. For example, the "Elemental Impurities Guide" of the Chinese Pharmacopoeia gives strict intake limits. The maximum daily intake of arsenic is 15 micrograms for oral and injection administration, and 2 micrograms for inhalation administration; YY 0334-2002 "General Requirements for Silicone Rubber Surgical Implants" requires that arsenic in implants be controlled below 5 micrograms per gram; the "Chinese Pharmacopoeia" stipulates that the arsenic salt content in gelatin (capsule shell additives or hemostatic sponge additives) is not more than 0.0001% (i.e. one part per million/1 microgram per gram). Because organisms in the ocean accumulate heavy metals, there are clear requirements for the control of arsenic in raw materials for medical devices obtained from marine extracts. For example, the Chinese Pharmacopoeia stipulates that the arsenic salt content in chitosan shall not exceed 1 part per million (i.e. 1 microgram per gram), and YY/T 1293.5 "Contact Wound Dressings - Alginate Dressings" stipulates that the arsenic content shall not exceed 2 micrograms per gram.

By strictly selecting raw materials, strictly controlling production processes, and strictly implementing factory inspections, the arsenic content in food, medicines, and medical devices can be controlled within the acceptable range for the human body, thereby ensuring that the arsenic ingested by the human body through these pathways does not exceed the safety upper limit. Therefore, there is no need to be afraid of arsenic. Choosing regular channels to buy food and regular hospitals and pharmacies for medical treatment can avoid excessive arsenic intake to the greatest extent and ensure safety.

References

[1] Limits of Contaminants in Food (GB 2762-2005)

[2] Cereal Complementary Foods for Infants and Young Children (GB10769-2010)

[3]AA Meharg, G Sun, PN Williams, E Adomako, Inorganic arsenic levels in baby rice are of concern, Environmental Pollution 152 (2008) 746-749

[4] “Infant rice cereal: containing arsenic does not mean it is harmful”, Guokr.com

[5] Pharmacopoeia of the People’s Republic of China, 2015 edition, Part IV

[6] YY 0334-2002 General Requirements for Silicone Rubber Surgical Implants

[7] YY/T 1293.5 Contact wound dressings – Alginate dressings

Source: Biomaterials Biological Evaluation Branch of Chinese Society of Biomaterials