Serum prolactin in subjects occupationally exposed to manganese.
To evaluate whether or not occupational exposure to manganese (Mn) affects basal levels of serum prolactin (PRL), a cross-sectional study was carried out in 31 occupationally-exposed workers, aged 39.2 years (DS 7.9) exposed to manganese (Mn) dusts for 14.5 years (range: 5 to 29 years) in a ferroalloy producing plant. Thirty-four industrial workers not exposed to neurotoxic chemicals and of comparable age composed the control group. Airborne Mn concentrations in dusts of the furnace area ranged 210 to 980 micrograms/m3, which is below the current American Conference of Governmental Industrial Hygienists (ACGIH)-recommended threshold limit value-time weighted average (TLV-TWA) of 1 mg/m3. Manganese concentrations in blood Mn (MnB) and in urine (MnU) were significantly higher in Mn-exposed workers as compared to control workers. The Mn-exposed workers showed significantly higher serum prolactin (PRL) levels with the geometric mean (GM) being 9.77 ng/ml with a geometric standard deviation (GSD) of 1.69 as compared to controls (GM 4.65 ng/ml, GSD 1.78, p < 0.001). Serum PRL was negatively related to age and positively correlated with both MnB and MnU. Dose-effect relationships were still significant in partial correlation analysis after control for age. The prevalence of abnormally high PRL values was consistent with a dose-response relationship. The observed increase in serum PRL among Mn-exposed workers suggests an impairment of tonic inhibition by tubero-infundibular dopaminergic neurons. The correlation between PRL and both MnB and MnU in samples collected at least 48 h from the last exposure suggests that such indices provide an estimation of the target dose.
Mutti
A
A
Laboratory of Industrial Toxicology, University of Parma Medical School, Italy.
Bergamaschi
E
E
Alinovi
R
R
Lucchini
R
R
Vettori
M V
MV
Franchini
I
I
D000328:Adult; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008345:Manganese / Q000009:adverse effects* / Q000097:blood / Q000652:urine; D008875:Middle Aged; D016273:Occupational Exposure; D011388:Prolactin / Q000097:blood*
D008345:Manganese; D011388:Prolactin