The relationship between environment and human body is a long-standing relationship of mutual connection, mutual restriction and interaction in the history of biological development. Due to the diversity and complexity of the objective environment and the unique subjective initiative of human beings to transform and utilize the environment, the relationship between the environment and human beings is extremely complicated. In the long-term development of human beings, the human body has formed a certain regulatory function to adapt to the abnormal changes in the environment; As long as the change of environment is not beyond the adaptability of human body, it will not destroy the balance of human body's adaptability to the environment, and human health and living ability will not be affected. However, the human body's ability to adapt to environmental changes is limited. If there are any drastic abnormal changes in environmental conditions (such as dramatic changes in meteorological conditions, natural or man-made pollution, etc. ), beyond the normal physiological adjustment range of human beings, it may cause abnormal reactions of some functions and structures of the human body, and even pathological changes, thus causing diseases or affecting people's lives.
(1) Endemic goiter
Endemic goiter is mainly an endemic disease characterized by compensatory goiter caused by iodine deficiency. Clinically, patients with onychomycosis have no obvious symptoms except for the gradual thickening of the neck. When glands oppress the surrounding organs, some local symptoms may appear, such as palpitation, shortness of breath, dyspnea and so on. Children in areas with severe endemic thyroid diseases may be complicated with endemic cretinism. The clinical characteristics of children with cretinism are dullness, short stature, deafness, dumb and paralysis in different degrees. A disease that has become a burden to families and society is difficult to cure.
This disease is the most widespread chemical endemic disease in the world, and it is estimated that there are more than 200 million patients in the world. This disease is prevalent in many places in China, especially in northwest, north China and southwest China. There are more mountainous areas than plains, more inland areas than coastal areas, and more rural areas than cities. People of all ages can get sick, even newborns. The main cause of this disease is the lack of iodine in the environment. Iodine is an essential trace element for human body to synthesize thyroxine. Iodine deficiency can promote the obvious proliferation of thyroid follicles and lead to compensatory enlargement of thyroid gland. Epidemiological investigation shows that iodine is deficient in soil, drinking water or food in most endemic goiter areas, and iodine content is closely related to the prevalence rate. After iodine supplementation, the prevalence of goiter can be controlled.
The prevention and treatment of endemic goiter should focus on prevention and combine prevention with treatment. At present, the main preventive method is to supplement iodine to the residents in the ward. China has a good experience in the method of iodine supplementation, that is, supplying iodized salt and iodized edible oil, and supplying iodized salt is simple and effective.
Iodized salt: also known as healthy salt, it is generally made by adding L-2 parts of potassium iodide to 6.5438+10,000 parts of salt and mixing evenly. Epidemic areas should adhere to long-term consumption. Iodized salt should be stored in a dry, low-temperature and dark place, and sealed and packaged.
In addition, providing iodine-rich food (kelp, marine fish and other seafood), reasonable diet, clean drinking water and regular life can reduce the incidence of endemic goiter.
(2) Endemic fluorosis
Endemic fluorosis is a chronic systemic disease characterized by dental fluorosis and skeletal fluorosis caused by long-term excessive intake of fluoride. This disease is very popular and occurs in all continents of the world. Fluorosis is widespread in more than ten provinces and cities in North China, Northwest China and Southwest China.
Etiology: Excessive fluoride exposure is the main cause of this disease. According to the survey, when the total daily intake of fluorine exceeds 4 mg, it may accumulate in the body, leading to chronic poisoning. The higher the fluorine content in drinking water and food, the higher the prevalence of endemic fluorosis. When malnutrition, especially calcium deficiency and vitamin A, D and C deficiency, can promote the occurrence of skeletal fluorosis.
Pathogenesis: There are still different understandings about the pathogenesis of skeletal fluorosis and mottled enamel teeth. However, according to clinical and experimental data, fluoride has the following toxic effects, which is helpful to clarify the pathogenesis of this disease.
A. Disrupting calcium and phosphorus metabolism: excessive fluoride combines with calcium to form calcium fluoride, which is mainly deposited in bone tissue and a small amount in cartilage, making bones hard and causing a series of symptoms. The combination of fluoride and calcium reduces blood calcium, thus stimulating the secretion of parathyroid gland to increase, strengthening osteolysis, accelerating bone absorption and making osteoporosis or softening. This phenomenon is more common in lying-in women and lactating women.
B. Inhibition of enzyme activity: Because fluorine combines with calcium and magnesium to form insoluble calcium fluoride and magnesium fluoride, many enzyme activities that need calcium to participate in the body are inhibited. For example, inhibition of oligoenolase and succinate dehydrogenase. , make the tricarboxylic acid cycle disorder, reduce glycogen synthesis, and cause bone tissue malnutrition; The inhibition of bone phosphorylase leads to the absorption and accumulation of calcium salt in bone tissue.
C. Effect on teeth: A proper amount of fluorine can replace the hydroxyl group of hydroxyapatite in enamel to form fluorapatite. It is the basic component of teeth, which can make enamel smooth and hard, acid-resistant, wear-resistant, and acid-resistant. Fluorine can also inhibit lactobacillus in the oral cavity and reduce the acidity produced by carbohydrate decomposition, thus having the function of preventing dental caries. However, excessive fluoride enters the body and a large amount of fluoride is deposited in the tissue, which may affect the formation of normal prismatic structure of enamel, form irregular spherical structure, produce spots, defects or stripes, reduce the hardness, brittleness and fragmentation of teeth, and even fall off early.
clinical picture
A mottled enamel teeth: the most obvious symptom of endemic fluorosis. Permanent teeth, especially incisors, are the most obvious. The surface of teeth is rough and dull, with spots, defects or stripes of different sizes and shapes, such as white, brown or brown. Teeth are fragile and easy to be damaged or fall off.
B skeletal fluorosis: the main clinical manifestations of patients are low back pain, joint stiffness, bending of upper and lower limbs and hunchback. Serious can cause limb and trunk joint fixation, and even paraplegia.
Precautionary measures: First, find out the source of fluorine. If it mainly comes from drinking water, it is necessary to replace the appropriate water source. Generally speaking, the fluorine content of surface water is lower than that of groundwater. If it is difficult to replace the water source, the method of reducing fluoride in water should be adopted. The commonly used method is basic aluminum sulfate method. Adding 0.05% g/L to the water and stirring for half a minute can reduce the fluoride in the water from 7.0 mg/L to 65,438 0.0 mg/L. There is also an aluminum sulfate method, in which aluminum sulfate is added to the water in an amount of 100 ~ 200mg/L, stirred evenly and left standing1-.
In addition, reduce the fluorine content in food, such as not using fertilizers with high fluorine content (such as phosphate rock powder). ) In areas with high fluorine content, not baking foods with high fluorine content and strengthening the monitoring and supervision of fluorine content in foods are all effective measures to prevent endemic fluorosis.