Elveated Heavy Metals Levels And Its Effect On Growth And Development Of Neonates In An E-waste Recycling Town

Background The rapid development of modern science and technology accelerates the generation of new electronic products. In the meantime, the obsoleted electronic products are increasing at an astonishing rate, and have become the world's largest source of electronic wastes. Most of these electronic wastes enter Asia, most of which are sent to China. Guiyu, a town in Guangong Province, is one of the destinations of the electronic wastes. These electronic wastes contain variety of poisonous hazard. The most harmful substances are heavy metals such as Lead, Cadmium, Mercury, Chromium and the etc. These substances cause serious problems to the society, environment, and public health if recycled not properly. Guiyu has more than 10 year history of electronic wastes recycling. The primary process method is manually handling and disassembling. This primitive and uncontrolled method spreads harmful substance to the surroundings. As a result, the heavy metal levels in local environment had far exceeded regulation. As we all known, embryo stage is the most critical time in human life development. The embryo is vulnerable to hazardous substances especially, to those mentioned above. However, there is no report on studies about heavy metal levels inside newborns in the electronic waste recycle regions. Therefore, we took Guiyu town of Guangdong Province as investigation site and, Guiyu local newborns as study object, collected surveys from mothers of these infants, and spent two yeas of investigations to local newborns regarding the levels of Lead, Cadmium and Chromium in their bodies. In the meantime, we studied nerve behavior development; the ALAD gene polymorphism, the placenta metallothionein expression, and the umbilical cord blood lymphocyte DNA damage situation; discussed the effect of heavy metal pollution to the newborns' growth and development; and assessed the harmfulness of unscientific electronic waste recycling to the public health of this region.Objective To investigate the abnormal birth rate of newborns in Guiyu. To explore the load condition of Lead, Cadmium and Chromium, the trend of its changes, and its relation to newborns' growth and development in electronic wastes recycling area. To assess the harmful effect to public health due to unscientific electronic waste recycle.Methods First investigates Guiyu area lying-in women and newborns' birth situation from 2003 to 2007 by reviewing available records. Next take the newborns from Guiyu local hospital as the research objects, categorized as Exposure Group; take those born from Chaonan Minsheng Hospital, categorized as Control Group. Utilize the atomic absorption spectrophotometry methods to monitor in 2006 and in 2007, umbilical cord blood Lead levels, meconium Lead levels, umbilical cord blood Cadmium levels, placenta Cadmium levels, umbilical cord blood Chromium levels of newborns; and survey in the form of question and answer to the family and working conditions of the newborns' parents. Apply the international approval BaoXiulan 20 items of newborns neonatal behavioral neurological assessment to grade the newborns' nerve behavioral capability. Apply Restriction fragment length polymorphism (RFLP) method to analyze ALAD gene. Use S-P immunity histochemistry technology to examine placenta metallothionein expression. Use the The Comet Experiment to examine newborns' umbilical cord blood lymphocyte DNA damage situation.Results 1. Comparison of Guiyu Group to Xiamen Group Data indicated that Guiyu Group had significant higher still death rate than Xiamen Group did each year from 2003 to 2007 as well as the totals of 2003 to 2007. Guiyu Group had higher premature delivery rate than Xiamen Group did each year from 2003 to 2007 as well as the totals of 2003 to 2007 except in 2005. Guiyu Group had higher low body weight rate than Xiamen Group did each year from 2003 to 2007 as well as the totals from 2003 to 2007. Guiyu Group had higher twin rate than Xiamen Group did each year from 2003 to 2007 but lower in 2006. The total twin rate from 2003 to 2007 was higher in Guiyu Group.2. 1) In 2006 the Guiyu area newborns umbilical cord blood Lead levels (mean: 113.28μg/L) was significantly higher than its neighboring towns (mean value: 60.43μg/L). The difference had statistics significance (P < 0.01). 48 occurrence exceeded current known safety guideline (100μg/L), counting 48% of this group. In 2007 the Guiyu area newborns umbilical cord blood Lead levels (mean: 110.86μg/L) was significantly higher than its neighboring towns (mean: 53.38μg/L). The difference had statistics significance (P < 0.01). 59 occurrences exceeded present safety guideline (100μg/L), counting 59% of this group. In 2007 the Guiyu group umbilical cord blood Lead mean was lower than what in 2006, but the two lead levels distribution did not have significant difference (P > 0.05).In 2006 the Guiyu area newborns meconium lead levels mean was 2.501μg/g, significantly higher than its neighboring towns meconium Lead levels (mean: 1.200μg/g). The difference had statistics significance (P < 0.01). In 2007 the Guiyu newborns meconium Lead levels mean was 4.54μg/g. However, in 2007 meconium the lead levels were higher than in 2006. The distribution had significant difference (P < 0.01). Parents' Engaging with the electronic wastes recycle, living in this area and the length of living in this area were factors of high lead load newborns.2) In 2006 the Guiyu group had umbilical cord blood Cadmium mean of 5.30μg/L, exceed rate was 20%. In 2007 the mean was 3.47μg/L, exceeding rate was 10%. Both Guiyu two years mean and exceeding rates were higher than those in the same year in Control Group (P < 0.01). In addition, both mean and exceeding rate of Guiyu Group in 2007 were lower than what in 2006, the difference had statistics significance (P < 0.01). In 2006 Guiyu Group newborns placenta Cadmium mean was 0.17μg/g, much higher than Control Group (0.10μg/g). The difference had statistics significance (P< 0.01). Parents' Engaging with the electronic wastes recycle, living in this area and the length of living in this area were factors of high Cadmium load newborns.3) Umbilical cord blood Chromium levels in 2006, Guiyu Group's levels (mean: 303.38μg/L, median: 93.89μg/L) had 29 occurrences exceeding current acceptable safe limit (0.20μg/L), exceeding rate 29%. Control Groups' levels (mean: 20.30μg/L, median: 18.10μg/L) was within current acceptable safe limit. Comparing Guiyu Group and Control Group, the difference had statistics significance either in the exceeding rate or in the mean. Umbilical cord blood Chromium levels in 2007, Guiyu Group's levels (mean: 99.90μg/L, median: 70.60μg/L) was higher than current acceptable safe limit: 9 occurrences, exceeding rate 9%. Control Group's levels (mean: 32.48μg/L, median: 24.00μg/L) was within current acceptable safe limit. Comparing Guiyu Group and Control Group, the Chromium exceeding rate and the mean, the differences had statistics significance. The differences of Guiyu Group umbilical cord blood Chromium mean and exceeding rate between 2006 and 2007 had no statistic significance (P > 0.05). There were positive correlations were found between umbilical cord blood Lead levels and Cadmium levels and Chromium levels.3. Lead sensitivity gene ALAD of newborns in electronic waste recycle area had various statuses. Nationwidely, the frequency of local newborns Lead sensitivity gene ALAD2 was at relatively low levels. This research so far had not discovered ALAD gene type correlation with newborns umbilical cord blood Lead levels.4. There were 67 placenta samples metallothionein of 100 totals in Guiyu Group, showing positive expression, positive rate 67%. There were 17 placenta samples metallothionein of 57 totals in Control Group, showing positive, positive rate 32.69%. Guiyu Group had much higher positive rate (P < 0.01).The placenta metallothionein expression quantity had positive correlation with umbilical cord blood Cadmium level and placenta Cadmium level of newborns.5. Comparison all subjects (t test) between Guiyu Group and Control Group. Guiyu Group neonatal behavioral neurological total scores, stands still reflection, behavioral capability, and non-biology vision directional responses had significant difference (P < 0.05). The initiative myo-tensity, pulls the reflection, non- biology directional hearing response, biological directional vision and hearing responded did not have significant difference (P > 0.05). Meconium Lead value had remarkable negative correlation with newborn behavior nerve assessment, initiative myo- tensity, behave capability, lead-pull reflection, stand still reflection, non- biology directional hearing response, non- biology directional vision response, and biological directional hearing and vision response had remarkable. However, the umbilical cord blood Lead value did not have correlation with them. Cord blood Cadmium and Chrome levels had negative correlation with newborn behavior nerve assessment. Core blood Cadmium levels had negative correlation with behave capability. Cord blood Chrome levels had negative correlation wirh non-biology directional vision response.6. There were remarkable differences (P < 0.05) of tailing rate and tail long between Guiyu Group and Control Group. In addition, there was correlation between DNA damage and umbilical cord blood Chromium and Cadmium levels of newborns.Conclusion The abnormal birth rate of neonates in Guiyu was at a relatively high level. A portion of newborns in electronic waste recycle area were in high Lead, high Cadmium, and high Chromium load condition. Although newborns in 2007 had lower Cadmium, and Chromium load levels than in 2006, but still at high level compared with national average. Parents' Engaging with the electronic waste recycle, living in Guiyu area and the length of living in this area were influencing factors of Lead, Cadmium, and Chromium load on newborns. From genetic characteristics view, local newborns were less susceptible to Lead in heredity, and there was no seen relevance of ALAD gene with Guiyu newborns umbilical cord blood Lead levels. But Guiyu newborns blood Lead levels were still at high level. This fact indirectly explained that the environmental pollution due to unregulated electronic waste recycle in Guiyu is threatening local newborns' health. Human body will produce more MT when induced by Cadmium exposed in the environment, which is one of the important human body self protection mechanisms. The MT level varies with the quantity of Cadmium in the environment. Through examining the quantity of placenta MT, this research further reveals the fact of pollution in Guiyu area, and the sensitivity of placenta to the Cadmium exposed in environment. Excluding internal factor influence to newborn Cadmium levels, environment is the primary factor that causes newborn Cadmium levels higher than acceptable level. Through neonatal behavioral neurological assessment, this research alerts that the Lead/Cadmium/Chrome exposure in Guiyu area will possibly affect the growth of newborn nerve behavior. It will potentially hinder the development of newborns central nerve system particularly, the development of their intelligence. Umbilical cord blood lymphocyte DNA of newborns damage situation alerts that Guiyu area Chromium and Cadmium pollution perhaps already endangered newborns' health, which can lower the quality of local new population. It will possibly lead to serious consequence if we do not pay enough attention to the pollution in the environment now.