Copper Sulfate is designated as “Generally Recognized as Safe” by the FDA: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=184.1261
|TITLE 21–FOOD AND DRUGS|
|CHAPTER I–FOOD AND DRUG ADMINISTRATION|
DEPARTMENT OF HEALTH AND HUMAN SERVICES
|SUBCHAPTER B–FOOD FOR HUMAN CONSUMPTION (CONTINUED)|
Subpart B–Listing of Specific Substances Affirmed as GRAS
|Sec. 184.1261 Copper sulfate.|
“Copper sulfate has been used for over 50 years in nutritional supplements with no
reports of toxicity or side effects”, and is safe in amounts up to 750 mg.
In chicken feed at 150 ppm, “Histological examination of the small intestine suggests that copper sulfate resulted in a healthier intestinal lining with a more absorptive surface.”
In rats, copper sulfate reduced heart disease: “The group that was given copper sulfate experienced a decrease in serum cholesterol. Copper concentrations in the aorta of the heart increased as cell damage and the accumulation of cholesterol plaque decreased.”
“Copper Sulfate Begins To Be Toxic At 750 mg – 375 times The RDA Dose”
Extoxnet states, “The lowest dose of copper sulfate that has been toxic when ingested by humans is 11 mg/kg (750 mg for a 150 pound person),” according to the National Research Council publication Drinking Water and Health, published by National Academy Press, Washington, DC, 1977, on pages 10-22.
“While Extoxnet states that 750 mg is the approximate starting toxic dose for a 150 pound person, they also state that copper sulfate is not actually lethal until it is ingested in the 10,000 to 11,000 milligram range, which is about 5,000 times higher than the 2 mg RDA. At the 2 mg RDA dose, copper sulfate is simply an essential nutrient, not a toxin or poison.”
“Signs of Toxicity – Humans
- Signs and symptoms from oral exposure include metallic taste, nausea, vomiting, diarrhea, and upper abdominal pain.28 Symptoms are affected by stomach acidity and content.3 Green or blue coloration of the vomit, stool, and saliva have been reported.29 Corrosion of the gastrointestinal epithelium may occur.3 Copper exposure may also cause failure of the liver, kidneys, and circulatory system.28
- Additional signs including dark brown or red urine, decreased urine production, gastrointestinal bleeding, jaundice, bluish skin or mucous membranes, delirium, and coma have been reported in patients who ingested up to 50 g of copper sulfate.30“
Humans get nauseous at levels of over 3mg of copper:
- A group of 179 adults from Ireland, Chile, and the U.S. were exposed once weekly to a solution of copper sulfate (0, 2, 4, 6, and 8 mg Cu/L) for 5 weeks. Acute LOAEL and NOAEL were determined at 6 and 4 mg Cu/L. Nausea within 15 minutes after exposure was the most common observed effect. Vomiting, diarrhea, and abdominal pain were also reported to a lesser extent.43 These results were confirmed in two additional independent experiments involving a total of 1634 people from around the world.44,45 See the text box on NOAEL, NOEL, LOAEL, and LOEL.
- Researchers administered copper sulfate dissolved in tap water at doses of 0, 1, 3, and 5 mg Cu/L for 2 weeks to groups of 15 healthy adult women. Subjects drank an average of 1.64 L per day. Reported symptoms include nausea, abdominal pain, and vomiting at exposure ≥3 mg Cu/L.46“
“Copper absorption can be enhanced by the presence of proteins and organic acids, such as citric acid and acetic acid, and inhibited by phytate, zinc, iron, molybdenum, calcium, and phosphorous.5“
- Excess copper is excreted and not often stored in the body.64
- Copper is primarily excreted in the feces through the bile; it can also be excreted to a much smaller extent in the urine, sweat, and by normal sloughing of the skin. Women can also eliminate very small amounts of copper through menstruation and men can eliminate it in semen. Small amounts can also be eliminated in hair and nails.5
- Subjects ate food dosed with radiolabeled copper and a whole-body scanner was used to measure retained copper levels. Half-lives ranged from 13 to 33 days in the body.65“
Source: National Pesticide Information Technical Fact Sheet on Copper Sulfate http://npic.orst.edu/factsheets/archive/cuso4tech.html
“Therapeutically copper sulphate has been used as a topical antifungal agent, and as an antidote in phosphorus poisoning (via phosphide formation). In veterinary practice it is used as an anthelmintic, emetic and fungicide and for treating copper deficiency in ruminants.”
“According to studies, the lowest dose of copper sulfate that had a toxic effect on humans is 11 mg/kg.” My note: 150 lb man / 2.2 pounds/kilo = 68.1818 x 11 = 750 mg, as reported above.
: National Institute for Occupational Safety and Health (NIOSH). 1981–1986. Registry of toxic effects of chemical substances (RTECS). Cincinnati, OH: NIOSH.
I note, copper sulfate, at 750 mg, appears to be far safer than the “tolerable upper limit” for “copper” set at 10 mg.
Do not take copper sulfate with magnesium?
Density: 2.3 g/cm3
That means copper sulfate is used as a dewormer.
“Medically, copper sulfate can be used as a fungicide, bactericide and astringent.” Copper Sulfate is used in dog food as a nutrient. https://www.petfoodindustry.com/articles/4185-copper-sulfate-a-standard-of-reference-for-copper-in-petfood People’s comments on this article include concerns that copper is toxic.
Further debate on the safety of copper sulfate’s use in dog food, 2014: https://www.dogfoodadvisor.com/canine-nutrition/copper-sulfate-dog-food/
Further criticism of copper sulfate appears to complain about it’s “excessive” use.
“1997 Growth supplement for livestock created a deadly disease for dogs.”
“In 1997, the Association of American Feed Control Officials (AAFCO) changed the requirements related to copper supplementation in companion animal diets. The requirements state that when “added” to diets, chelated copper or copper sulfate (man-made coppers) must be used.”
I noted in some of the dog food ingredients that calcium was an ingredient 4 times, but there is no magnesium, nor any boron added.
A vet’s dog died of excess copper, but there is no note for how much copper was in the dog food: https://www.battlecreekenquirer.com/story/news/local/2015/01/11/battle-creek-vet-crusades-help-keep-dogs-healthier/21523561/
Copper Sulfate in Humans:
“When dietary copper is high and more copper is absorbed, mainly through the gastrointestinal tract, excretion of copper from the body increases, protecting against excess accumulation of copper in the body. Depending on the copper status in the body at the time, approximately 20 to 60% of dietary copper may be absorbed. Copper absorption is also affected by other factors such as species, age, chemical form, and pregnancy. When copper intake is low, little copper is excreted from the body, protecting against copper depletion”
Copper Sulfide is added to infant formula:
“We have copper in our Organic Premium Infant Formula because it’s required by law and, more importantly, vital to infant health. We chose the cupric sulfate form because it’s more bioavailable — meaning it’s more readily available for absorption (2,3). One study found that infants absorb and retain about 75% of the copper in breast milk, but only 52% from copper-fortified formula (4). By choosing a form that’s more bioavailable, we hope to provide an infant formula that’s closer to the nutrient profile of breast milk.”
“In the case of copper in infant formula, the recommended amount set by the government (200 mcg) is roughly 3,750 times less than the dose that is shown to elicit even the smallest adverse human health effect (750,000 mcg) (1, 6).”
That is the third mention of the 750 mg limit of “smallest adverse human health effect”.
That source, (6) links to the correct or current link, here: http://pmep.cce.cornell.edu/profiles/extoxnet/carbaryl-dicrotophos/copper-sulfate-ext.html
The Extoxnet article says “The lowest dose of copper sulfate that has been toxic when ingested by humans is 11 mg/kg (8).”
Source 8: National Institute for Occupational Safety and Health (NIOSH). 1981- 1986. Registry of toxic effects of chemical substances (RTECS). Cincinati, OH: NIOSH.
The Extoxnet article further notes: “Copper sulfate is highly corrosive to plain steel, iron and galvanized pipes. All metal in contact with solutions of this material should be 304 stainless steel, monel or plastic (6). It should not be stored in metal containers. Copper sulfate is also incompatible with acetylene gas and with magnesium metal (13). “
“The amount of copper sulfate that is lethal to one-half (50%) of experimental animals fed the material is referred to as its acute oral lethal dose fifty, or LD50. The LD50 for copper sulfate is 30 mg/kg in rats.”
I note, if I were a rat, since I weigh 100 kg, that would be 3000 mg, or 3 grams.
A 10 pound bag of copper sulfate crystals is $30.
Apparently, copper sulfide “reacts” to potassium iodide. https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=184.1265
How much copper to take?
For copper deficiency myelopathy: “Oral copper supplementation of 8 mg/day was started and resulted in progressive clinical improvement and normalization of serum copper levels after 8 months.”
Other uses of copper sulfate: https://copperalliance.org.uk/about-copper/copper-compounds/uses-copper-sulphate/