2.1. Time and location of sampling
This research was carried out in 2016. The research was carried out in three different locations. Data collections were carried out in Tangerang Regency, Medan City and Surabaya City. This research uses a sample of children who are still in elementary school with an age range of 7 – 12 years. Samples were selected based on the following criteria:
a. Private and state elementary schools that have been established and operating since at least 1995 in Tangerang Regency, Medan City and Surabaya City;
b. Elementary school students in grades 2, 3, and 4, male and female, and already living in Tangerang Regency, Medan City, and Surabaya City
c. Respondents were willing and permitted their parents to participate in the research.
d. Respondents were in good health or had recovered from illness for at least 7 days before blood sampling was carried out.
2.2. Tools and materials
The tools and materials used in the blood sampling process are Tanderlett lancet, alcohol swab, capillary tube, wound plaster and for blood sample analysis using Lead Care Portable Analyzer (ESA Laboratories, Chelmsford, MA, USA), Test Kit (Treatment Reagents) Lead Care II, as well as Blood Lead Testing System.
2.3. Sample analysis
Data collection was carried out by a team consisting of researchers from the Quality Research and Development Center and Environmental Laboratory (P3KLL) which has now become the Center for Standardization of Environmental Quality Instruments (PSIKLH) under the Ministry of Environment and Forestry, Faculty of Public Health (FKM) – University of Indonesia (UI), local Health Service, and Non-Governmental Organizations (NGOs).
2.3.1. Preliminary survey
In the initial stage, hold discussions with the school to collect a permission form and study equipment for testing BLL. Permission/consent forms and questionnaires that have been filled in by parents/guardians and have been collected previously from each school principal. Then the research team explained the blood collection procedure and answered questions asked by the principal or other school staff related to this research.
2.3.2. Blood sampling
After the entire procedure has been conveyed to the student's parents via a consent form and the school has understood the stages of data collection, then students who have received approval from parents and the principal are taken to a room (principal's office/classroom) which is has been prepared and conditioned for the location where the blood will be drawn. After permission from the parents and verification and verbal consent from children aged 7 years and over, blood samples were taken by a medical blood collection team from the local sub-district health center.
2.3.3. Blood sample analysis
Blood samples were analyzed for BLL in a cooled room. This was done to reduce the possibility of environmental contamination of the collection site and could also be due to the upper threshold for the lead instrument's operational range care analyzer is 95 o F, while the air temperature in the field is usually higher. Nearly all blood samples are analyzed on the day they are taken. Blood samples that have been analyzed are not stored but are collected together with all the equipment that has been used (i.e., needles, blood tubes, gauze and gloves) in a special container for the disposal of dangerous goods. Blood samples were destroyed after the entire series of research reports were completed.
Sampling method and analysis of BLL were carried out according to the Lead instrument manual Care Portable Analyzer (ESA Laboratories, Chelmsford, MA, USA). Blood samples for Pb were then analyzed using Lead Care Portable Analyzer (ESA Laboratories, Chelmsford, MA, USA), which will analyze the Pb concentration of blood samples with anodic stripping voltammeter that has been developed by the Cooperative Research and Development Agreement with CDC-USA. This method has been used successfully by CDC-USA in various types of American and international research and the accuracy of the tool has been verified in many studies.
The blood sample that will be taken is peripheral blood via the fingertips. Respondents' hands were washed with clean water and soap, dried with tissue paper, then wiped with alcohol and dried with gauze. The tip of the middle finger is then pricked with a Tenderlett lancet sterile disposable. Approximately 50 µl (4 drops) of blood coming out of the fingertip is collected in a capillary tube for Pb analysis. After the blood is taken, the tip of the finger is covered with a wound plaster (band aid).
The analysis procedure includes placing a blood sample into a reagent tube and giving the blood sample the opportunity to stay in the tube for 1 to 2 minutes, which is then inserted into the lead care electrode measuring device. The results of the analysis on the lead care electrode only appear and can be read about 3 minutes later.
2.4. Ethics in clearance
According to Decree Number: 244/UN2.F10/PPM.00.02/2015, dated October 22, 2015, this research has received ethical clearance approval from the Research and Community Health Service Ethics Commission, Faculty of Public Health, University of Indonesia.