Dose-Response Relationship between Cumulative Occupational Lead Exposure and the Associated Health Damages: A 20-Year Cohort Study of a Smelter in China.

Long-term airborne lead exposure, even below official occupational limits, has been found to cause lead poisoning at higher frequencies than expected, which suggests that China's existing occupational exposure limits should be reexamined. A retrospective cohort study was conducted on 1832 smelting workers from 1988 to 2008 in China. These were individuals who entered the plant and came into continuous contact with lead at work for longer than 3 months. The dose-response relationship between occupational cumulative lead exposure and lead poisoning, abnormal blood lead, urinary lead and erythrocyte zinc protoporphyrin (ZPP) were analyzed and the benchmark dose lower bound confidence limits (BMDLs) were calculated. Statistically significant positive correlations were found between cumulative lead dust and lead fumes exposures and workplace seniority, blood lead, urinary lead and ZPP values. A dose-response relationship was observed between cumulative lead dust or lead fumes exposure and lead poisoning (p < 0.01). The BMDLs of the cumulative occupational lead dust and fumes doses were 0.68 mg-year/m³ and 0.30 mg-year/m³ for lead poisoning, respectively. The BMDLs of workplace airborne lead concentrations associated with lead poisoning were 0.02 mg/m³ and 0.01 mg/m³ for occupational exposure lead dust and lead fume, respectively. In conclusion, BMDLs for airborne lead were lower than occupational exposure limits, suggesting that the occupational lead exposure limits need re-examination and adjustment. Occupational cumulative exposure limits (OCELs) should be established to better prevent occupational lead poisoning.

Clinical evaluation of oral levofloxacin 500 mg once-daily dosage for treatment of lower respiratory tract infections and urinary tract infections: a prospective multicenter study in China.

Levofloxacin (LVFX), a fluoroquinolone agent, has a broad spectrum that covers Gram-positive and -negative bacteria and atypical pathogens. It demonstrates good clinical efficacy in the treatment of various infections, including lower respiratory tract infections (LRTIs) and urinary tract infections (UTIs). To evaluate the efficacy and safety of oral LVFX 500 mg once daily, a large open-label clinical trial was conducted in 1266 patients (899 with LRTIs and 367 with UTIs) at 32 centers in China. In the per-protocol population, the clinical efficacy rate (cure or improvement) at 7 to 14 days after the end of treatment was 96.4% (666/691) for LRTIs and 95.7% (267/279) for UTIs. In 53 patients diagnosed with atypical pneumonia the treatment was effective. The bacteriological efficacy rate was 96.6% (256/265) for LRTIs and 93.3% (126/135) for UTIs. The eradication rate of the causative pathogens was 100% (33/33) for Haemophilus influenzae and 96.0% (24/25) for Streptococcus pneumoniae in LRTIs, and 94.1% (80/85) for Escherichia coli in UTIs. The overall efficacy rates were 89.3% (617/691) for LRTIs and 87.8% (245/279) for UTIs. The incidence of drug-related adverse events (ADRs) was 17.3% (215/1245), and the incidence of drug-related laboratory abnormalities was 15.7% (191/1213). Common ADRs were dizziness, nausea, and insomnia. Common laboratory abnormalities included "WBC decreased", "alanine aminotransferase (ALT) increased", "aspartate aminotransferase (AST) increased", and "lactate dehydrogenase (LDH) increased". All of these events were mentioned in the package inserts of fluoroquinolones including LVFX, and most events were mild and transient. Thirty-four patients (2.7%) were withdrawn from the study because of the ADRs. No new ADRs were found. This study concluded that the dosage regimen of LVFX 500 mg once daily was effective and tolerable for the treatment of LRTIs and UTIs.