Influence of the GSTP1 rs1695 Polymorphism on Mercury Levels

Overview

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assess Hg levels and the GSTP1 rs1695 polymorphism. Hg levels ranged from 0.1 µg/g
to 6.5 µg/g (median = 1 µg/g, IQR = 1.43). Individuals with impaired memory and
mean Hg levels, compared to individuals with the GSTP1GG genotype (β = −0.46). These
in recent years, ASGM activity has increased by more than 90% in the Brazilian Amazon (3).
convenience sample (n = 178). For the present study, all adults (i.e., individuals aged over
coefficient of variation (CV) was below 15%. If the CV exceeded 15%, a fourth measurement
analyses remained within the acceptable range. Mercury levels above 2.0 µg/g of hair were
a significance level of 5% was adopted.
ranged from R $1501 t o R$ 7200, and most individuals consume fish and Brazilian nut at
least once a week (Table 1).
Table 1. Sociodemographic characteristics of participants, Rondônia, Amazon, Brazil, in 2023.
a Age in years; b Missing information from 2 individuals (n = 111); c Missing information from 1 individual
Mercury levels from the 113 samples ranged from 0.11 µg/g to 6.5 µg/g in the general
analysis (Table 2) and, therefore, were included as covariates in the subsequent analyses.
Table 3 presents the linear regression models exploring the association between neuro-
IC 95%: 2.18–6.60; p < 0.001) as did those with reduced muscle strength (β = 1.24; IC 95%:
Weinberg equilibrium, with the GSTP1 G allele frequency at 21.3% in the study population.
than those with the AA genotype, after adjusting for sex, age and fish consumption (Table 4).
Table 2. Linear regression models between sociodemographic characteristics and mercury exposure
(IQR) Estimate (β) Standard Error 95% CI p-Value
Table 3. Linear regression models between neurological evaluation outcomes and mercury exposure
(n = 113) Estimate (β) Standard Error 95% CI p-Value
every 1 µg/g increase in mean mercury levels, the score on the delayed recall test decreases
for each 1 µg/g increase in mean mercury levels (p-value = 0.04; Adjusted R2 = 0.16),
Table 4. Linear regression models between the GSTP1 SNP and mercury exposure levels, Sete de
Estimate (β) Standard Error 95% CI p-Value a
polymorphism remained statistically significant (Supplementary Tables S2 and S3). The
main characteristics of these individuals are described in Table 5. Most of the individuals
had the GSTP1 rs1695 AA genotype and almost 90% of them presented at least one alteration
Table 5. Sociodemographic characteristics of the 26 participants with Hg levels ≥ 2.0 µg/g, Rondônia,
a Age in years; b Missing information from 1 individual (n = 25); c fourteen people have never attended school
(n = 12). d Brazilian reais (BRL); e fish consumption at least once a month; f any alteration found during the
lives in an urbanized context and shows an obesity prevalence 20% higher than the average
range considered normal (≥6 figures identified) (42), yet it is already possible to observe an
polymorphism, even when the GSTP1 SNP is rearranged into the recessive model, may limit
digenous Territory, Rondônia, Amazon, Brazil, 2023; Table S2: Linear regression models between
levels ≥ 2.0 µg/g, Sete de Setembro Indigenous Territory, Rondônia, Amazon, Brazil, 2023; Table S3:
1. Strange, R.C.; Jones, P.W.; Fryer, A.A. Glutathione S-Transferase: Genetics and Role in Toxicology. Toxicol. Lett. 2000,

Methods (brief)

collected using a validated methodology. Hair and oral mucosa cells were collected to
convenience sample (n = 178). For the present study, all adults (i.e., individuals aged over
underwent a neurological evaluation, and provided both hair and oral mucosa samples
(further details below) were included (n = 113). The sample of children will be included in
(D) clinical and laboratory assessments; (E) oral mucosal cells collection; (F) hair sample collection;
laboratory assessments were conducted (Figure 1D), hair and oral mucosa samples were
collected (Figure 1E,F), and anthropometric measures were taken. BMI was calculated as
2.5. Biological Samples Collection
Hair samples of approximately 1 cm in diameter were collected from the occipital
total Hg dose (exposure levels). The samples were then stored in individually identified
Epithelial cells were collected from the oral mucosa using sterile swabs, to access the
of NaCl, and distilled water to a final volume of 1 L. Subsequently, the samples (swab stored
Total mercury (THg) from hair samples is known to be a reliable biomarker of MeHg
30 days preceding sample collection (29,30). THg analysis in hair samples was performed
using the RA-915M mercury analyzer coupled with the PYRO-915+ pyrolysis unit (Lumex
in Hg(II) to its atomic state through thermal decomposition (pyrolysis) of the sample.
vs. mercury mass), using the Zeeman-effect background correction atomic absorption
spectrometry method (Zeeman AAS).

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Update history

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