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INFORMATION SYSTEM: ESTIMATION OF CADMIUM EXPOSURE
Abstract
The limitation of duplicate meals for dietary exposure assessment, required technical
expertise, time frame and budget, the assessment could not be processed by the
community. A community information system for the estimation of dietary exposure to
cadmium was initiated and introduced as a tool for the impact assessment of the people
living downstream of zinc mining site. The system requires the recent cadmium
determination in food items, especially rice and other food crops, fishes, shellfishes and
livestock that were grown, raised, and caught in the contamination area, and amounts of all
food consumed in each meal for a day. The system estimated cadmium exposure as
estimation daily intake (EDI) and compared to tolerable daily intake (TDI) set by European
Authorities at 0.8 microgram per kilogram body weight with 10 percent of the uncertainty
addition. The results page was filled with the individual estimation values, chart and text for
interpretation or information relating to the assessment such as warning and further impacts
information. The individual data could be saved and viewed for the periodic assessment.
The initial stage of the system validation revealed that rice grown in the contamination area
was a major food staff for cadmium exposure among the community. The system also links
to environmental and health surveillance data, knowledge, and other information that can
support the community driven information center
Introduction
The environmental cadmium contamination was reported near zinc mine in Mae Taw Greek,
Northwestern Thailand (Pollution Control Department, 2004). Exposure to cadmium in
contaminated area has been shown at high levels in body burden (Teeyakasem et al., 2007;
Swaddiwudhipong et al, 2007 and Swaddiwudhipong et al, 2010) to cause adverse health
effects. The epidemiological studies in the study site reported the associations of cadmium
body burden and kidney damage (Swaddiwudhipong et al, 2015), hypertension
(Swaddiwudhipong et al, 2010a), bone disease (Nambunmee K, 2014) and kidney stone
(Swaddiwudhipong et al, 2010b). Cadmium can be accumulated in the food chain and
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detected in all food stuff including rice grain (Satarug et al, 2010). Rice is the staple food
consumed among the resident in the contaminated area. Cadmium has a long biological
half-life in human and body and excessive amounts of cadmium ingestion in food chain to
be taken daily can considerably increase the risk of chronic health problems.
Duplicate meals is commonly used approach for estimation of dietary exposure for dietary
exposure assessment of toxic chemicals (Melnyk et al, 2014). It has to perform the collection
of duplicates of individual consumed foods and participants provide duplicate portions of all
foods eaten over the monitoring period (Bradman et al, 2007 and Riederer et al, 2010). It
requires technical expertise, laboratory, time frame and budget, the assessment could not
be processed by the community. Therefore, the system was aimed to develop a community
self-assessment tool for an estimation of dietary exposure to cadmium.
Estimated daily intake (EDI) of Cd through food consumption
The tolerable daily intake (TDI) recommended by the Joint FAO/WHO Expert Committee on
Food Additives (JECFA), show appropriate safe exposure levels ingested over a lifetime
without appreciable risk (WHO, 2004). The TDI of Cd in this study was calculated according
to the guide values based on the tolerable daily intakes of Cd set by JECFA most recent
evaluation at 0.8 µg/day kg body weight (JECFA (2011). The daily intake of metals depends
on both cadmium intake from food and the body weight of the human that can influence the
tolerance of contaminants.
TDI = C x A x Bw
Where C; is the concentration of cadmium in contaminated food (µg/kg);
A; stands for the amount of daily average consumption of food; and
Bw represents the body weight (kg)
In our community based assessment system, the EDI is introduced as the same TDI concept
using the amount of daily cadmium intake and body weight. In term of daily cadmium intake,
calculation is accounted by the summary of amount of cadmium in each food items
consumed. The concentration of cadmium from food is derived from the recent cadmium
analysis from environmental monitoring. The self-assessment form is used for recording the
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items and amount as serving unit of food consumption. The system is set for data input as
the number of serving unit for each food consumed for each meal and the total amount of
cadmium can be calculated by the amount of daily food intake. Therefore, the EDI is
calculated as follows:
EDI = (C x A) x Bw
Where C; is the concentration of cadmium in co each contaminated food (µg/kg);
A; stands for the amount of daily average consumption of each food item (serving unit); and
Bw represents the body weight (kg)
Estimation of cadmium exposure using information system
The system performs an estimated dietary exposure to cadmium that comprises of four main
variables, type and quantity of food consumptions, sources of food stuff, amount of
cadmium contamination in food and uncertainty. The system requires the recent cadmium
determination in food items, especially rice and other food crops, fishes, shellfishes and
livestock that were grown, raised, and caught in the contamination area. The amounts of all
food consumed in each meal for a day using the survey form is inserted to the system and it
estimates dietary cadmium exposure as EDI and compared to TDI set by European
Authorities at 0.8 microgram per kilogram body weight with 10 percent of the uncertainty
addition.
The initial outcome of system implementation
The initial stage of the system implementation showed that the system could be used as a
tool for the estimation of dietary exposure to cadmium by the community. According to the
high contamination was detected in the rice grain cropped locally and dietary nutrition
intake survey for the system validation suggesting the consumption of local rice induced
excessive Cd intake among the community because rice is a staple food in the
contaminated site. The 10 percent of the uncertainty addition. The results page was filled
with the individual estimation values, chart and text for interpretation or information relating
to the assessment such as warning and further impacts information. The individual data
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could be saved and viewed for the periodic assessment. The results page was filled with the
individual estimation values, chart and text for interpretation or information relating to the
assessment such as warning and further impacts information. The individual data could be
saved and viewed for the periodic assessment. In regards to the estimation of cadmium
intake among volunteers showed the cadmium intake was excessed the TDI value
recommended and the attention should also be paid for exposure and risk reduction.
Conclusions
This community information system can be used for the estimation of dietary exposure to
cadmium. The linkage of the information system to environmental and health surveillance
data, knowledge, and other information can support the community driven information
center. The updated information of cadmium amount for food item harvested or slaughtered
should be conducted for improving the dynamic cadmium contamination resulting the more
accurate outcomes of the estimation dose.
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