Understanding Potential Heavy Metal Contamination,

Overview

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and As, which are highly toxic to human exposure, are recommended to be 1.0 µg/kg body
Table 1 shows the summary of heavy metal concentration in paddy plants and soil in
due to their adsorptive nature in soil (29). Meanwhile, the metals in rice plants are found
also have reported that concentration of As was found to be the highest (4.62 mg/kg) in
accumulation, as shown in Table 1.
harvest season in 2013 were severely polluted with Cd with a total mean of 1.4 mg/kg (37),
dard (0.3 mg/kg) and the corresponding background values of Hunan (0.098 mg/kg).
accumulated by 0.13 mg/kg and 0.08 mg/kg, respectively (45,46). It was reported that
Yap et al. (51), Aziz et al. (52), and Payus et al. (53) in three different areas. Based on Table 1,
Table 1. Summary of heavy metals concentration in paddy plants and soil in selected areas of different countries.
tings are trivial in the range of 10 to 15 ppm of most trace elements suitable for most
tively, based on the basis of dry weight (w/w) in mg/kg. If the BAF is ≤ 1, then the
whereas BAF > 1 means that the heavy metals accumulate in plants (28,32). According to
Table 2 summarizes BAF values in paddy plants from different areas by several studies.
From Table 2, the BAF values for Mn (1.88) from Neeratanaphan et al. (95) and all metals
Table 2. Summary of the bioaccumulation factor (BAF) values in paddy plants from different areas.
Table 3 summarizes TF values in paddy parts from different areas by various studies.
Table 3. Summary of the translocation factor (TF) values in paddy plants from different areas.
present, especially in food and drinks. Table 4 tabulates the mathematical models for risk
CDIInhalation = (4)
CDIIngestion = (6)
Table 4. Mathematical models for risk assessment on heavy metal exposure. Adapted from EPA (147).
In determining the HRI value, the equation shown in Table 4 involves the ratio between
and locality of inhabitants may not be similar. (153). Table 5 shows non-carcinogenic risk
used to determine HI. The HQ formula that is shown in Table 4 is almost similar to HRI,
based on Chien et al. (159), Yang et al. (160), and Fang et al. (161), as shown in Table 4.
area. Similarly, Wang et al (164) has revealed that the mean value of THQ for Cd exceeded
Meanwhile, in Iran, Djahed et al. (137) discovered that As has a HQ value more than 1,
constituents, as shown in Table 5, by assuming additive effects in order to calculate the
With reference to Table 5, Satpathy et al. (32) reported the HI values of heavy metals
Table 5. Non-carcinogenic risk assessment from rice consumption in selected areas of different countries.
calculated using the equation that is shown in Table 6 in order to estimate the incremental
values were slightly higher than the acceptable range, which are 3.5 × 10−4 for adults and
As in rice with 100% bioaccessibility for consumers. Therefore, the authors concluded
As is not 100% in food commodities. The consumption of local brown rice by people in
Table 6 shows the summary of carcinogenic risk assessment via rice consumption in
Table 6. Carcinogenic risk assessment via rice consumption in selected areas of different countries.
Food Regulation (182) with a decreasing order of Zn (4.3 mg/kg) > Fe (1.9 mg/kg) > Cu
(1.1 mg/kg) > Al (0.89 mg/kg) > Cr (0.11 mg/kg) > Co (0.032 mg/kg) > Cd (0.027 mg/kg)
Pb (0.022 mg/kg) > As (0.016 mg/kg).
(Table 7), by reducing their concentration in soil, and finally reducing their rice uptake.
Table 7. Mitigation methods for reducing heavy metals availability in rice grains.

Methods (brief)

in vitro digestion models through a vital ingestion portion of rice.
risk. In this regard, it also covers information regarding in vitro digestion models that can
sub-samples. Generally, As is found to be of the highest metal uptake by the roots in
In China, paddy soils that were collected from three areas of Hunan Province during
Area of Study Sample(s) References
Area of study Sample(s) Cd As Pb Cr Cu Zn
Area of Study Sample(s) References
The As speciation in rice grain is dominated by dimethylarsinic acid (DMAV ) and inorganic
sample by the ratio of the element concentration in the grain to that in the corresponding
the samples that accumulate metals > 1 mg kg−1 , and < 1, respectively. The toxic effect of
values that were greater than 1, which indicates that the samples have relatively high
Cn = Heavy metal concentrations in samples (mg/kg)
Dn = Daily intake of samples (mg/person/day)
MC = Metal concentration in samples (mg/kg)
Cb = Heavy metal concentrations in samples (mg/kg)
rice from the collected samples is probably unsafe.
ingestion of local brown rice. Praveena and Omar (167) found that rice that was collected
and waste discharge. For Malaysia, a study on 22 varieties of marketed rice samples to

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The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised