The harm and toxicity of heavy metals

1. Hazards and Symptoms of Lead Poisoning

(1) Leads to neurological dysfunction, resulting in neuropathy and toxic polyneuritis.

(2) Inhibits hemoglobin synthesis and has a hemolytic effect, causing anemia in animals, as well as affecting the clotting process and damaging the kidneys.

(3) Impairs immune function, making animals susceptible to disease.

(4) Causes malformations, mutations, and carcinogenic effects.

Symptoms of Poisoning

Lead poisoning caused by feed is mainly a chronic process. Symptoms include digestive disorders and neurological symptoms, such as loss of appetite, constipation or alternating constipation and diarrhea, abdominal pain, lethargy, limb pain, emaciation, anemia, and lead lines at the gum margin.

Hazards of Arsenic

(1) Causes cellular metabolic disorders and leads to neurological dysfunction.

(2) Leads to changes in vascular wall permeability, causing organ congestion and damage.

(3) Causes a drop in poultry and livestock quality, seriously affecting production.

(4) Has teratogenic, mutagenic, and carcinogenic effects.

Symptoms of Poisoning

Acute arsenic poisoning is usually caused by accidental ingestion, while chronic poisoning can occur through long-term ingestion of small amounts through feed. Symptoms include neurological and digestive dysfunction, depression, skin pain, decreased touch sensation, limb weakness and paralysis, emaciation, rough and dull fur or feathers, hair loss and hoof shedding, loss of appetite, digestive disorders, abdominal pain, persistent diarrhea, infertility or abortion in female livestock.

Hazards and Symptoms of Cadmium Poisoning

(1) Cadmium accumulates slowly and is poorly excreted, damaging the renal tubules and glomeruli, causing proteinuria, glucosuria, and calcium phosphate excretion, leading to osteoporosis and bone pain. It also causes anemia and significant damage to the animal reproductive system. Cadmium interferes with the absorbance of Zn, Cu, and Fe, and has carcinogenic effects. The LD50 of cadmium in chickens is 165-188 mg/kg body weight. Adding 30-60mg/kg Cd to the daily diet of laying hens can reduce the body weight, feed conversion ratio, egg production, and eggshell thickness.

(2) Symptoms of Poisoning

Anemia is a chronic disease caused by cadmium poisoning. Symptoms include rough fur or feathers, lack of lustre, decreased appetite, lethargy, long-term diarrhea, weight loss, slow growth, decreased egg production in laying hens, reduced egg weight, decreased pork weight gain, decreased productivity, pale mucous membranes, increased susceptibility to disease, and unexplained death.

Hazards and Toxicity of Chromium

(1) Toxic effects on the liver: Many studies have shown that the liver is the main target organ of chromium toxicity. Exposure to Cr(VI) can cause liver damage in animals. Chromium is reduced by reducing agents in food after entering the body. Unreduced chromium absorbed through the intestines enters the blood and is reduced by blood in the liver, where it can cause toxic reactions in liver cells.

(2) Toxic effects on the kidneys: The kidneys are the primary excretory organs for chromium entering the body, which can cause kidney damage. Studies have reported that the proximal tubules are the main sites of early kidney injury, which can lead to increased proteinuria, changes in kidney function, and even renal function changes. Chromium can also cause kidney toxicity by inducing oxidative and membrane damage.

(3) Toxic effects on the lungs: Chromium exposure through the respiratory system is an important pathway. Cr(VI) can cause strong respiratory irritation and corrosive damage to the respiratory tract, especially affecting the nasal cavity and pharynx, causing diseases such as nasal septum perforation and asthma.

(4) Toxic effects on reproductive organs: Studies have shown that male rats injected with potassium dichromate for five consecutive days developed testicular atrophy and decreased sperm count after 60 days, while female rats developed fetal malformations and decreased fetal weight, and even miscarriage. Three-valence chromium has also been found to impair oocyte maturation and to lower the number of superovulated ova, survival rate of oocytes, and in vitro fertilization rate in mice, indicating significant reproductive toxicity.