312
Trace Elements in Abiotic and Biotic Environments
Strontium can bind to proteins and, based on its similarity to Ca, probably forms
complexes with various inorganic anions, such as carbonates and phosphates, carboxylic acids, citrates and lactates (WHO 2010). The Sr contents of foods showed a
correlation with their Ca contents (Varo et al. 1982). Due to chemical similarity of Sr
and Ca, the stable forms of Sr do not pose a significant health threat.
Strontium stimulates bone growth, increases their density. At its low contents
bone fractures mainly in women may occur, escpecially at women (Cabrera et al.
1999; Genuis and Bouchard 2012). Strontium ranelate is a new orally administered
agent for the treatment of women with postmenopausal osteoporosis. Strontium
ranelate was chosen from among 20 different Sr compounds based on the bioavailability of Sr, gastric tolerability, and physicochemical characteristics (Blake et al.
2007). Women receiving the drug showed a 12.7% increase in bone density. Women
receiving a placebo had a 1.6% decrease. It is evident that Sr-containing biomaterials
have positive effects on bone tissue condition and repair (Isaac et al. 2011).
Research on the Sr toxicity has so far been focused mainly on the biological effects
of radioactive 90 Sr, which is an important constituent of nuclear fallout. At that time
dietary supplementation of stable Sr was reported to inhibit the intestinal absorption
of 90 Sr, thereby serving as a deterrent to ingestion of radioactive Sr (Cabrera et al.
1999). Radioactive 90 Sr can lead to various bone disorders and diseases, including
bone cancer. 90 Sr concentrates in bone surfaces and bone marrow, and its relatively
long radioactive half-life (29 years) makes it one of the more hazardous products of
radioactive fallout.
The International Agency for Research on Cancer (IARC) has determined that
radioactive Sr is carcinogenic to humans, because it is deposited inside the body and
emits β radiation. External and internal exposures to fission products including 90 Sr
causes solid cancers and leukemia (IARC 2012b).
Medically, radioactive Sr probes have been used intentionally to destroy unwanted
tissue on the surface of the eye or skin. Radioactive Sr may cause cancer, as a result
of damage to the genetic material DNA in cells. An increase in leukemia, over time,
was reported in individuals in one foreign population who swallowed relatively large
amounts of 90 Sr (and other radioactive materials) in river water contaminated by a
nuclear weapons plant.
For adult humans, the total daily intake of Sr, in many parts of the world, is
estimated to be up to about 4 mg/day. Drinking water contributes about 0.7–2 mg/
day, and food (mainly leafy vegetables, grains and dairy products), and another
1.2–2.3 mg/day (Table 45.2). The contribution from air is insignificant (WHO
2010). For adults in the United States, the total daily exposure to Sr has been estimated to be approximately 3.3 mg/day, made up of 2 mg/day from drinking water,
1.3 mg/day from the diet, and 0.4 μg/day from inhaled air (ATSDR 2004c). The
population dietary intake in the United Kingdom was 1.3 mg/day in 1994 yr, and
1.20 in 2006 yr. The greatest contributions, from various food groups, to dietary
intake of Sr are: bread (20%), vegetables (15%), and cereals (14%) (Rose et al.
2010). Cigarettes and tobacco leaves contain Sr, and individuals who smoke may
be exposed to its higher levels.
Trace Elements in Abiotic and Biotic Environments
Strontium can bind to proteins and, based on its similarity to Ca, probably forms
complexes with various inorganic anions, such as carbonates and phosphates, carboxylic acids, citrates and lactates (WHO 2010). The Sr contents of foods showed a
correlation with their Ca contents (Varo et al. 1982). Due to chemical similarity of Sr
and Ca, the stable forms of Sr do not pose a significant health threat.
Strontium stimulates bone growth, increases their density. At its low contents
bone fractures mainly in women may occur, escpecially at women (Cabrera et al.
1999; Genuis and Bouchard 2012). Strontium ranelate is a new orally administered
agent for the treatment of women with postmenopausal osteoporosis. Strontium
ranelate was chosen from among 20 different Sr compounds based on the bioavailability of Sr, gastric tolerability, and physicochemical characteristics (Blake et al.
2007). Women receiving the drug showed a 12.7% increase in bone density. Women
receiving a placebo had a 1.6% decrease. It is evident that Sr-containing biomaterials
have positive effects on bone tissue condition and repair (Isaac et al. 2011).
Research on the Sr toxicity has so far been focused mainly on the biological effects
of radioactive 90 Sr, which is an important constituent of nuclear fallout. At that time
dietary supplementation of stable Sr was reported to inhibit the intestinal absorption
of 90 Sr, thereby serving as a deterrent to ingestion of radioactive Sr (Cabrera et al.
1999). Radioactive 90 Sr can lead to various bone disorders and diseases, including
bone cancer. 90 Sr concentrates in bone surfaces and bone marrow, and its relatively
long radioactive half-life (29 years) makes it one of the more hazardous products of
radioactive fallout.
The International Agency for Research on Cancer (IARC) has determined that
radioactive Sr is carcinogenic to humans, because it is deposited inside the body and
emits β radiation. External and internal exposures to fission products including 90 Sr
causes solid cancers and leukemia (IARC 2012b).
Medically, radioactive Sr probes have been used intentionally to destroy unwanted
tissue on the surface of the eye or skin. Radioactive Sr may cause cancer, as a result
of damage to the genetic material DNA in cells. An increase in leukemia, over time,
was reported in individuals in one foreign population who swallowed relatively large
amounts of 90 Sr (and other radioactive materials) in river water contaminated by a
nuclear weapons plant.
For adult humans, the total daily intake of Sr, in many parts of the world, is
estimated to be up to about 4 mg/day. Drinking water contributes about 0.7–2 mg/
day, and food (mainly leafy vegetables, grains and dairy products), and another
1.2–2.3 mg/day (Table 45.2). The contribution from air is insignificant (WHO
2010). For adults in the United States, the total daily exposure to Sr has been estimated to be approximately 3.3 mg/day, made up of 2 mg/day from drinking water,
1.3 mg/day from the diet, and 0.4 μg/day from inhaled air (ATSDR 2004c). The
population dietary intake in the United Kingdom was 1.3 mg/day in 1994 yr, and
1.20 in 2006 yr. The greatest contributions, from various food groups, to dietary
intake of Sr are: bread (20%), vegetables (15%), and cereals (14%) (Rose et al.
2010). Cigarettes and tobacco leaves contain Sr, and individuals who smoke may
be exposed to its higher levels.