The effects of lead exposure on psychological test performance and subjective feelings of well-being were investigated in 40 exposed workers whose PbB levels had never exceeded 60 micrograms/100 ml and in 20 controls matched for sex, age and educational level. The exposed workers were divided into two groups of 20, with recent PbB levels in the range 45-60 micrograms/100 ml or below 35 micrograms/100 ml. The group of workers with the higher PbB levels showed significantly poorer performance and reported more physical symptoms than the other two groups. These differences were unrelated to sociodemographic and personality characteristics. A principal component analysis suggested that the poorer performance was mainly due to an impairment of general functioning and only to some extent to a deterioration in specific functions, such as verbal reasoning and abstraction. Higher lead concentrations were correlated with poorer performance and a higher number of physical complaints. These results indicate that in exposed workers the threshold for impaired performance lies below the blood-lead concentration of 60 micrograms/100 ml, which is the current threshold limit value (TLV).
1 The relationship between lead uptake level and subjective psychological and physical symptoms was investigated in two groups of occupationally exposed workers with PbB levels between 45 and 60 μg/100 ml and below 35 μg/100 ml respectively. Findings were compared with those of a non-exposed control group. 2 Psychological symptomatology as defined by the GHQ proved unsensitive to low levels of lead exposure, while physical symptomatology as defined by the SSQ, in particular neurological symptoms, showed a significant tendency towards an uptake response relationship. 3 The minimum uptake level for neurological symptoms in this study was below 35μg/100 ml.
1 In a group of 108 workers professionally exposed to low lead levels and in 35 shoe factory workers exposed to a mixture of solvents, neurotoxic effects were evaluated by means of Critical Flicker Frequency, used as single test of psychophysiological performance. 2 A statistically significant lowering of CFF threshold was observed and, in the lead exposed group, this decrease is related to the biological parameter zinc protoporphyrin. 3 The usefulness of CFF measure in environmental toxicology, together with other neurophysiological tests, is considered.
Serum pyruvate kinase and creatine kinase activities were measured in a group of patients with various neuromuscular diseases and in carriers of muscular dystrophy. Elevated values of PK were usually but not invariably associated with elevated levels of CK. THe data showed that PK activity was elevated in all patients with DMD, high values generally correlating inversely with age or disease duration. In definite carriers, the level of PK was raised simultaneously with CK, while in potential carriers, classified by their relationship with MD patients in mothers, sisters and other relatives, the PK levels were elevated in 23%, 44% and 10% respectively, indicating especially for sisters, an increased genetic probability of being a definite carrier. In this way, we have confirmed that the serum PK assay is more sensitive in younger subjects and that combined CK and PK measurement will be of value in detecting a higher proportion of potential carriers.
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