**4.3 Relationship between brain damage caused by lead, low intelligence quotient and renal dysfunction**

Acute encephalopathy occurs in children of blood lead concentration of ≥80 g/dl [70], therefore low threshold of 30–70 g/dl has been suggested [71]. Every increase of 10 g/dl in blood lead caused a loss of 4—7IQ points, hence it is difficult to identify a threshold for decrement in IQ [72, 73]. Renal dysfunction was caused by lead concentration of blood at <40–70 g/dl, and 10 g/dl was associated with 9% reduction in creatinine clearance [74, 75]. Nevertheless, 85 g/dl blood lead caused increased susceptibility to cold and >50 g/dl caused significant immunological changes [76], such as increase in lymphocytes, abnormal T-cell subsets and cellular immune function [77, 78]. Lead concentration of >62 g/dl inhibited conversion of vitamin 2 into 1.25 dihydroxy vitamin 2 which was reduced in children with severe renal insufficiency, at blood lead concentration of 33–55 g/dl [79]. Nevertheless, blood lead concentration of 14 g/dl caused low birth weight, premature birth and increased risk of developmental abnormalities [80]. Threshold level for hypohaemoglobinaemia is 50 g/dl in adult and ≤40 g/dl in children, respectively [38]. Regulatory bodies such as Control of Lead at Work (CLAW) and Scientific Committee on Occupational Exposure Limit (SCOEL)

have recommended 30 g/dl for female workers of child-bearing capacity and 60 g/dl for men and others. However, European Lead Association has recommended 30 g/dl for men and 10 g/dl for women with reproductive capacity, respectively [81, 82]. Mean blood lead concentration of pigs that fed on venison was 2.29 g/dl which is 3.6 times higher than that of pig that did not feed on venison (0.63 g/dl). The venison-fed pig eliminated lead within 6 days of last ingestion [45]. Blood concentration of lead >5 g/dl is associated with high risk of spontaneous abortion in woman and the concentration > 40 g/dl is associated with decreased libido, sperm count and abnormal morphology of sperm cells [83, 84].
