Influence Of D-aminolevulinate Acid Dehydratase And Vitamin D Receptor Gene Polymorphism On Lead Toxicity In Han Lead Workers In China

ObjectiveTo explore the effect of δ-aminolevulinate acid dehydratase （ALAD） andvitamin D receptor （VDR） gene polymorphism on blood lead, hemoglobin andserum calcium levels in lead workers, in order to supply the basic data in cohortresearch and reasonable evidence in selecting people who are more vulnerable to thetoxicity of lead.Methods1. Making a professional production environment hygienic survey in a lead acidbaterry factory in Wuhan in2011, giving an dynamic evaluation to lead smoke anddust concentration in this factory based on the existing data from2006to2011;2. Giving regular occupational health physical examination and questionnairesurvey to workers;3. Based on the distribution frequency of different ALAD and VDR alley inpeople, estimating the minimum sample size were125and222respectively, from allof387workers,186and230workers respectively were selected to determined theALAD genotype and VDR genotype by PCR-RFLP technique with the restrictionenzyme Mspâ…  and Bsmâ… , the serum calcium levels were measured by flameatomic absorption spectrometry;4. Comparing the effect of different ALAD genotype on blood lead andhemoglobin, analyzing the difference of blood lead and serum calcium levels inworkers with different VDR genotype;5. All of the data was input by Excel. SAS8.1was used for statistical analysis,and P=0.05is the standard of difference significant or not.Results1. Hygienic surveyThe data of environment detection from2006-2011in this factory showed thelead smoke and dust concentration in every lead work site went beyond the nationalstandard,0.03mg/m³and0.05mg/m³.The lead smoke concentration had thehighest level in welding work site, moreover presenting the trend of rising year afteryear, with the geometry mean0.355mg/m³, the lead dust concentration indistribution work site rose the highest levels and had big fluctuation, with thegeometry mean1.123mg/m³, the lead smoke and dust concentration had littlechange in other work sites in recent5years;Workers from welding work site are allocated3G facemask from import, havingmore rigorous personal protective measures, moreover welding workers work2hours every time on average, however, workers from other work site are givenordinary occupational protective facemask only and work8hours per shift;2. Comparison of blood lead from workers in different workshops in2011The distribution of blood lead in workers in different work site is consistentwith the distribution of lead smoke and dust in environment in general. Workersfrom distribution have the highest blood lead,327.92μg/L, the concentration of lead smoke in welding work site is high, but workers in this work site are given morerigorous protective measures, actually having less exposed dose, so the blood leadlevel is not high, only310.57μg/L, lower than melting workers whose workingenvironment had lower lead smoke concentration.3. The distribution of ALAD and VDR gene frequencyAmong186workers detected ALAD genotype, there were174ALAD₁₁homozygotes （93.55%）,12ALAD₁₂heterozygotes （6.45%） and no ALAD₂₂homozygotes were found. As for VDR gene, there were198VDR_bbhomozygotes（86.09%）,29VDTRBbheterozygotes （12.61%） and3VDR_BBhomozygotes （1.30%）. The distribution of ALAD and VDR genotype accords withHardy-Weinberg Balance.4. The comparison of blood lead and hemoglobin between different ALADgenotypeCompared to workers with ALAD11, workers with ALAD₁₂show a rising tendin blood Lead level, but no statistic difference is found （P>0.05）. The hemoglobinlevel is significantly lower in workers with ALAD₁₂（P<0.05）.5. The comparison of blood lead and serum calcium between different VDRgenotypeComparing the effect of different VDR genotype on blood lead and serumcalcium, the workers with VDRBallele have higher blood lead and lower serumcalcium than workers with VDRbbgenotype （P<0.05）.Conclusion1. The lead smoke and dust concentration in this factory overpass the nationalstandard severely, and have threatened the health to workers. The workingenvironment could not have improved in recent years, but strengthening personalprotective measures will lessen the influence of lead smoke and dust on workers’health.2. ALAD and VDR polymorphism both influence the lead toxicity, workerswith ALAD₁₂genotype is more vulnerable to lead blood toxicity. VDRBallele is alsoone of vulnerable alleles to lead toxicity, and the possible mechanism is relation tothe influence of VDR polymorphism on calcium metabolism and the similarmetabolic way between lead and calcium.