whole blood lead

Lead (plumbum, Pb), atomic weight 207.19, silver-gray soft metal. The specific gravity is 11.35 (20 ° C), the melting point is 327.4 ° C, and the boiling point is 1620 ° C. Valence 2 and 4. Do not dissolve in water, dilute hydrochloric acid and sulfuric acid. Soluble in nitric acid, acetic acid and lye. When heated to 400 to 500 ° C, a large amount of vapor is generated. Lead vapor is rapidly oxidized into lead oxide (Pb2O) in air. Common inorganic lead compounds are lead oxide (PbO, mitox), lead dioxide, lead dioxide (Pb2O3, 樟丹), lead pentoxide (Pb3O4, lead dan), lead chloride, lead sulfide (PbS) , black lead dan, black xidan), lead sulfate, lead nitrate, lead acetate and basic lead carbonate [2Pb[O2·Pb(OH)2], lead white]. In daily life, excessive lead is absorbed from the digestive tract (using lead-containing containers, food, drugs) and respiratory tracts such as automobile exhausts by >0.5 mg/d, which can cause lead poisoning and cause harm to health, mainly damaging the nervous system and blood system. Basic Information Specialist classification: growth and development check classification: biochemical examination Applicable gender: whether men and women apply fasting: fasting Tips: The instrument should be regularly verified with ZPP standard materials to ensure good performance. The background value of the coverslip directly affects the measurement results of ZPP, which needs to be cleaned and screened before use, and the background value is too high. Normal value (1) Fluorescence spectrophotometry of erythrocyte protoporphyrin 1 The normal reference value does not contact lead. The blood EP range is 57-511/μg/L (0.10-0.91/μmol/L), and the median is 227 μg/L (n=46). The national EP normal reference value survey results were geometric mean (GM) = 280 μg / L (0.50 μmol / L), P95 reference value range was < 610 μg / L (1.09 μmol / L) (n = 978). 2 Acceptable upper limit The acceptable upper limit of EP for occupational lead exposure population obtained by discriminant analysis is 1.29 mg/L (2.30 μmol/L) (n=902). 3 Diagnostic lower limit The lower limit of EP diagnosis of occupational lead poisoning obtained by discriminant analysis was 2.06 mg/L (3.67 μmol/L) (n=698). (2) Determination of blood lead by graphite furnace atomic absorption spectrometry To meet the needs of lead poisoning prevention and control, it is necessary to formulate three levels (three values) of B-Pb, that is, normal reference value, acceptable upper limit value and diagnostic lower limit value. . 1 Normal reference value Due to the geographical environment, living habits and social and economic conditions of different countries and regions, the normal reference values ​​reported by different countries are quite different. For example, in 1982, global B-Pb monitoring was carried out under strict quality control conditions. The geometric mean of B-Pb values ​​of teachers in the world's top ten cities was 0.31 μmol/L (64 μg/L) in Beijing and 1.09 μmol in Mexico City. /L (225 μg / L). In recent years, published in foreign literature, the normal reference value of B-Pb in non-lead people is 100-200μg/L (0.483-0.965μmol/L). According to the B-Pb test of 1588 people with non-lead normal population in different regions of China from 1991 to 1993, the upper limit of normal B-Pb in China was 0.90μmol/L (187μg/L) (Table 4). Wu Ronggui et al (1995) reported that the normal blood lead level in normal population in Guangxi was 0.403±0.178μmol/L (n=687), and male B-Pb (0.473±0.200, n=389) was significantly higher than female (0.333±0.157,n). =298) (P<0.01), which is close to B-Pb in Nanning area listed in Table 4, indicating that B-Pb in a normal area is relatively stable over a period of time. 2B-Pb acceptable upper limit B-Pb acceptable upper limit, also known as "biological exposure limit (BEL)", "biological contact index (BEI)" or "biological tolerance", refers to B-Pb Exceeding the upper limit of the normal reference value, but generally does not cause blood lead levels of lead poisoning, that is, this B-Pb level is acceptable. The B-Pb acceptable upper limit value obtained by the discriminant analysis method was revised to 444 μg/L (n=902). The BEI value of B-Pb proposed by American ACGIH (1991) is 500μg/L (2.41μmol/L). In the same period, the acceptable upper limit of children's B-Pb in US CDC (1992) is from the original 250μg/L (1.25). The μmol/L) was reduced to 100 μg/L (0.48 μmol/L) because it was reported that the child lost learning ability at a concentration of 100 μg/LB-Pb. 3B-Pb diagnostic lower limit B-Pb diagnostic lower limit There is no uniform standard in foreign countries. It is generally considered that B-Pb>3.86μmol/L (800μg/L) can show obvious lead poisoning performance. At present, B-Pb in China uses 2.41 μmol/L (500 μg/L) as the diagnostic lower limit. In recent years, a large-scale national survey on the diagnosis of chronic lead poisoning showed that the diagnostic lower limit of B-Pb obtained by discriminant analysis was 3.07 μmol/L (635 μg/L, n=698). (3) Red blood cell ZPP Rapid determination of the ZPP concentration of the factory workers who did not touch lead was 0.774±0.24 μmol/L (n=47). The upper limit of the normal reference value of blood ZPP proposed by the Collaborative Group for the Diagnosis of Lead Poisoning (1996) is 1.34 μmol/L (6.0 μg/gHb), and the upper limit of acceptance is 1.79 μmol/L (8.0 μg/gHb). The value was 2.91 μmol/L (13 μg/gHb). Clinical significance (1) Diagnostic significance of B-Pb B-Pb is a sensitive indicator reflecting recent lead exposure. A domestic survey showed that B-Pb was highly correlated with lead concentration in the air (r=0.6379, P<0.01, n=895), and there was a good dose-response relationship between lead exposure and aluminum toxicity (symptoms). . B-Pb and other indicators such as U-Pb (r = 0.7935, P < 0.0005, N = 895), EP (r = 0.7743, P < 0.001, n = 895) and ZPP (r = 0.7326, P < 0.0025, n =895) is also significantly correlated. In the current lead exposure hazard monitoring and diagnosis, B-Pb determination has become the preferred indicator in biological exposure indicators. B-Pb was used as the primary or only biomonitoring indicator in the study of the effects of lead on occupational exposure hazards, pregnancy (fetus), childhood cognitive ability, and adult renal function, and these adverse effects were observed. The concentration of B-Pb is related. While the US CDC announced in 1991 that the child lead exposure value was reduced from 250μg/L to 100μg/L, B-Pb was recommended as the best biomonitoring indicator for screening and diagnosing lead exposure in children. Since then, the demand for B-Pb determination has increased rapidly. (2) Diagnostic significance of U-Pb Urine lead can reflect the discharge of lead from the body and can indirectly reflect the amount of lead absorbed. However, because the U-Pb concentration is affected by factors such as measurement method, urine retention time, sample contamination, concentration and dilution, the results fluctuate greatly and cannot reflect the lead level in the body sensitively and reliably. Sometimes, although there is a large amount of lead accumulation in the body, the U-Pb emission is not high, and it is only increased after the lead-extension test. At present, U-Pb determination is mainly used to observe the effect of lead-exposed treatment. (3) Diagnostic significance of EP and ZPP The two porphyrin indicators of EP and ZPP have been widely used in the monitoring and diagnosis of occupational lead exposure hazards in the 70s and 80s. This is based on lead interference with porphyrin metabolism and affects heme synthesis, resulting in increased concentrations of EP and ZPP in red blood cells. Although the increase in EP and ZPP is not necessarily parallel to the severity of the disease, it has diagnostic value for lead poisoning. The national standard (GB11504-89) released in 1989 listed the porphyrin index as one of the diagnostic conditions for lead poisoning. In the 1980s, children's lead exposure was 1.21 μmol/L (250 μg/L), and EP was also a good indicator for children's lead exposure and iron deficiency screening. However, in the 1990s, in the United States and other countries, EP measurement was gradually eliminated, because the US CDC revised and promulgated the acceptable value of blood lead in children from 1991, from the original 1.21μmol / L (250μg / L) to 0.48μmol /L (100 μg / L), and requires direct determination of B-Pb, rather than screening B-Pb by indirect methods (such as ZPP). In some places in Canada, the upper limit of B-Pb acceptable for children and adult women was 0.48 μmol/L, and that for men was 0.72 μmol/L (149 μg/L). Due to the sensitivity of the method, ZPP could not screen children and adult women with subclinical lead poisoning with B-Pb elevation between 048 and 1.21 μmol/L. However, EP or ZPP still has great value in occupational lead exposure hazard screening. Especially in the production environment, when the peripheral blood is taken for EP measurement, the sample is not easily polluted by the environment, and the measurement result is consistent with the venous blood, and the peripheral blood lead has a certain deviation compared with the venous blood lead. In recent years, due to the simple, rapid and accurate domestically produced blood ZPP measuring instrument, the successful development and put into production has promoted the application of domestic blood ZPP determination in the screening and diagnosis of occupational chronic lead poisoning. (4) Diagnostic significance of urinary ALA In the lead poisoning, inhibition of erythrocyte δ-aminolevulinic acid dehydratase (ALA-D, EC4.2.1.24) leads to δ-aminolevulinic acid (ALA) in red blood cells, plasma and urine. The concentration has increased successively. In the early years, ALA in urine was used as an important means to screen for occupational lead exposure hazards. However, as measured by today's standards, this indicator is not sensitive enough to check lead toxicity, and is not ideal for early diagnosis, because the urine ALA concentration is only significantly increased when the B-Pb concentration is >1.93 μmol/L (400 μg/L). . Moreover, the requirement to quantitatively collect 24 hours of urine also limits its application. However, due to the simple measurement method, low test cost, and non-invasive sampling, it is still used in China's grassroots census, and it is also used in other countries. High results may be diseases: lead poisoning in children, lead poisoning precautions 1 The instrument should be regularly verified with ZPP standard materials to ensure good performance of the instrument. 2 The background value of the coverslip directly affects the measurement result of ZPP, which needs to be cleaned and screened before use, and the background value is too high. Inspection process Rapid determination of erythrocyte ZPP: 1 Instrument: ZPP-3800 blood zinc protoporphysin analyzer (developed by Guangdong Provincial Occupational Disease Prevention and Treatment Institute): 24mm × 24mm coverslip (Shanghai). 2 blood sample determination: take 20 ~ 30μl peripheral blood sample into the coverslip, cover the instrument measurement area, no bubbles, stir and push into the sample platform, read (or print) the results after the reading is stable. 3 Quality control: The ZPP content of the red blood cell ZPP standard substance is determined by the same operation as the blood sample measurement, and the result should be within the range of its nominal value. Not suitable for the crowd Generally no taboos. Adverse reactions and risks Subcutaneous hemorrhage: subcutaneous hemorrhage due to less than 5 minutes of compression time or blood draw technique.

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