EFFECTS OF METALS IN HUMAN

pixabay.com

In my last post, I talked about sources of metallic impurities, their classes of metals and permissible level.

Today I will be making a brief write-up on the effect of some selected metals.

---

---

Antimony

Human overexposure to antimony (Sb) and its compounds can adversely affect the skin, lungs, cardiovascular system and liver. The significant antimony compound is sulphides and, to a lesser extent, oxides of Sb(III) [1]. Because antimony is found naturally in the environment, the general population is exposed to low levels, primarily in food, drinking water, and air (most individuals consume about 5 micrograms of antimony per day).

---

---

Arsenic

Arsenic exerts adverse effects on the skin. It has a pronounced affinity for skin and keratinizing structures including the hair and nails. Therefore, symptoms of acute overexposure include a variety of skin eruptions, alopecia and characteristic striation of the nails [2].

It is worthy to note that Arsenic does not act as a sensitizer, due to the poor skin penetrating ability of its naturally occurring compounds [2].

• The health effects of arsenic in humans vary depending on the compound and form (Metallic, inorganic and organic form).
• Metallic arsenic is not absorbed by the gastrointestinal tract and does not have any known adverse health effects [3].
• Carcinogenicity has been observed only in its inorganic form [2]. Inorganic arsenic compounds are more acutely toxic than environmentally occurring organic arsenic (e.g. dimethylarsinate). Dermal uptake is expected to be very limited [4].It is therefore possible for children to ingest arsenic-containing cosmetics from hand-to-mouth contact (e.g. by rubbing their hands over the mouth and/or eating after rubbing the face) [3]
  

---

---

Cadmium

Cadmium is classified as a human carcinogen by the National Institute for Occupational Safety and Health (NIOSH). The absorption of cadmium through the skin is low (0.5%) and would be of concern only in situations where concentrated solutions would be in contact with the skin for several hours or longer. Cadmium binds to epidermal keratin when applied topically, thus explaining the limited dermal absorption observed in vitro. It is known that significant dermal exposure, as could occur in an occupational setting, can cause irritant dermatitis [2].

---

---

Chromium

Chronic exposure to Chromium may result in liver, kidney and lung damage. Skin irritation and ulceration are reported for low-level exposure, while long-term exposure causes kidney and liver damage. Accumulation in aquatic life, and by extension to humans that consume such fishes, that have been exposed to high level of Cr [5].

---

---

Copper

Copper is an essential element to human life. However, in high amount, anemia, liver and kidney damage, stomach irritation are common. Also, people suffering from Wilson’s diseases are easily affected by overexposure to copper. Copper normally occurs in drinking water from copper pipes, as well as from additives designed to control algal growth.

.,

---

---

Lead

Lead exerts adverse effects on numerous organs and systems including the central nervous system (CNS), the kidneys and on the hematopoietic (blood forming) system. Exposure to lead is typically greater in children and are also more susceptible to the effects of lead than adults.

Children are particularly at risk for the subtle adverse effects of chronic low-dose lead exposure, as are pregnant women/fetuses. The HHEB (Applied Nutrition Health Hazard Evaluation Board) concluded that the fetus may be harmed by its exposure to the average levels of lead, in table wine through its mother's consumption of this beverage. [6, 7]

Children absorb about 50% of ingested lead. The identification of causal relationships between exposure and effects is complicated by the delay between the time of lead exposure and the onset of effects.

Dermal absorption of inorganic lead has been demonstrated in animals and human subjects. Exposure to lead from cosmetics previously occurred from use of progressive hair dye preparations containing lead acetate [8], however, lead acetate is now prohibited for such use in cosmetics.

The HHEB determined that the daily intake of table wine containing 150 ppb or less of lead is likely to pose no more than a minimal risk to the adult population, including women of childbearing age. A recognized source of potential contamination of wine with lead occurs through the use of lead foil capsules on wine containers.

FDA (Food and Drug Administration) recommends that lead levels in candy products likely to be consumed frequently by small children not exceed 0.1 ppm because such levels are achievable under good manufacturing practices and would not pose a significant risk to small children for adverse effects.

The use of lead-based ink on candy wrappers that directly contacts food or, if such lead could be expected to migrate into the packaged food, the product is unsafe for consumption.

---

---

Mercury

Various forms of mercury are toxic. The form of mercury plays a role in how much is absorbed via dermal or oral routes. Forms of mercury are metallic mercury, Inorganic, and organic mercury compounds. All forms of mercury are absorbed through the skin, mucosa and dermal exposure can result in systemic toxicity. For the general population, the major route of mercury exposure is dietary intake [2]. Mercury compounds may cause allergic reactions, skin irritation, or adverse effects on the nervous system [9].

Clinical symptoms of overexposure to mercury include tremors, weakness, memory loss, dermatitis and impaired kidney function [10], with the form of mercury typically determining the specific symptoms. Exposure to mercury in medicines may be very limited, but the likelihood of exposure from food ingredients or dietary supplements may be much greater.

---

---

Nickel

Small amounts of Nickel are needed by the human body to produce red blood cells, however, in excessive amounts, it can become mildly toxic. Short-term overexposure to nickel is not known to cause any health problems, but long-term exposure can cause decreased body weight, heart and liver damage, and skin irritation. The most common adverse health effect of nickel in humans is an allergic reaction. People can become sensitive to nickel when jewelry or other things containing nickel are in direct contact with the skin. Once a person is sensitized to nickel, further contact with the metal will produce a reaction. The most common reaction is a skin rash at the site of contact. In some sensitized people dermatitis may develop at a site away from the site of contact. Cancer of the lung and nasal sinus, have occurred in people who have breathed nickel dust while working in nickel refineries or in nickel processing plants (11, 12).

---

---

Selenium

Selenium is needed by humans and other animals in small amounts, but in larger amounts, this can cause damage to the nervous system, fatigue, and irritability. Selenium accumulates in living tissue, causing high selenium content in fish and other organisms, and causing greater health problems in human over a lifetime of overexposure. Some health problems include hair and fingernail loss, damage to kidney and liver tissue, damage to circulatory tissue, and more severe damage to the nervous system [13].

The last I will include here is Zinc

---

---

Zinc

Less is known about the long-term effects of ingesting too much zinc, through food, water or dietary supplements. It is an essential trace element, but generally, ingestion of higher than recommended levels can have adverse effects on health. The recommended Dietary Allowances for Zinc are 15 mg/day for men and 12 mg/day for women. If doses 10 –15 times higher than these recommendations are taken by mouth, even for a short time, stomach cramps, nausea and vomiting may occur. Ingesting high levels for several months may cause anemia, damage to the pancreas, and decreased levels of high-density lipoprotein (HDL) cholesterol [14].

---

---

In conclusion

A total of 10 metals have been mentioned in this article, while metals like chromium may be present as impurities in food, drug products, cosmetic, the toxicological properties and corresponding risk associated with these substances are considered less significant than for lead, arsenic, cadmium, mercury and antimony.

---

---

Are you a STEM (Science, Technology, Engineering, and Mathematics) related posts author?, consider joining #steemSTEM on steemit chat or discord here.
Nigerian STEM authors may include the #stemng tag in their post. Visit @stemng for more details.
Check this blog post by @steemstem and this guidelines here for help on how to be a member of @steemstem.