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Pag. 11
The cyanotoxins occurrence in water and fresh foods: human health
implications
La presencia de cianotoxinas en aguas y alimentos frescos: implicaciones para la salud
humana
Nelfa Elizabeth España Francis
1
* ; Liliana María Gomez Luna
2
Received: 18/04/2024 – Accepted: 21/06/2024 – Published: 01/07/2024
Research
Articles
X
Review
Articles
Essay
Articles
* Author for correspondence.
Abstract
The cyanotoxins occurrence in water, and their incorporation into the food chain have caused numerous reports of health damage. This study presents a
systematic-critical review on the presence and implications of cyanotoxins in water and fresh foods, considering their potential impact on human health.
The applied methodology corresponds to a critical-narrative analysis of research published in institutional repositories and high-impact databases
(PubMed, Crossref, Google Scholar, Scopus) considering the last 10 years of documentary validity. The results demonstrate a recognition of the impact
of human activities and climate change on the increasing incidence of cyanotoxins on human well-being, with negative implications, related to
gastrointestinal symptoms, liver conditions and damage to the nervous system, the impact being relevant. of microcystins and cylindrospermopsins.
Emphasis is placed on the need to obtain precise data on the toxicological charge in both water, biomass, and fresh foods, to establish the pertinent
restrictions in order to provide health guarantees. Governments must take measures to prevent the risk associated with the presence of cyanotoxins, with
training and capacity building for research and management being necessary in vulnerable contexts. Mitigation of the impacts of cyanotoxins must be
treated from a communication and instructional point of view. It is important to develop awareness campaigns to improve perception of this emerging
risk, which often compromises the lives of human beings.
Keywords
cyanotoxins, foods, health damages, toxicity, water
Resumen
La presencia de cianotoxinas en las aguas y su incorporación a la cadena trófica, han causado numerosos reportes de daños a la salud. Este estudio presenta
una revisión sistemático-crítica sobre la presencia e implicaciones de las cianotoxinas en aguas y alimentos frescos, considerando su impacto potencial
para la salud humana. La metodología aplicada corresponde a un análisis crítico-narrativo de investigaciones publicadas en repositorios institucionales y
bases de datos de alto impacto (PubMed, Crossref, Google Académico, Scopus) considerando los últimos 10 años de vigencia documental. Los resultados
demuestran un reconocimiento del impacto de las actividades humanas y el cambio climático en la incidencia cada vez mayor de las cianotoxinas en el
bienestar humano, con implicaciones negativas, relacionadas con síntomas gastrointestinales, afecciones hepáticas y daños al sistema nervioso, siendo
relevante el impacto de las microcistinas y cilindrospermopsinas. Se hace énfasis en la necesidad de obtener datos precisos de la carga toxicológica tanto
en agua, biomasa, como en alimentos frescos, para establecer las restricciones pertinentes en función de dar garantías de salud. Los gobiernos deberán
tomar medidas para prevenir el riesgo asociado a la presencia de cianotoxinas, siendo necesarias en aquellos contextos vulnerables, la capacitación, y la
formación de capacidades para la investigación y la gestión. La mitigación de los impactos de las cianotoxinas debe ser tratada desde el punto de vista
comunicacional e instructivo. Es importante desarrollar campañas de sensibilización para mejorar la percepción sobre este riesgo emergente, que en
muchas ocasiones compromete la vida de los seres humanos.
Palabras clave
agua, alimentos, cianotoxinas, daños a la salud, toxicidad.
1. Introducción
Since their origin, cyanobacteria have had an impact on life,
either due to their significance in generating the oxygenic
atmosphere of Earth, forming the basis of the diet of various
peoples, or their ability to produce toxins that affect the
ecology of water bodies where they massively develop, with
socio-economic implications [1].
1
Universidad de Guayaquil / Facultad de Ingeniería Química, Carrera Ingeniería de Alimentos; nelfa.espanaf@ug.edu.ec ;
https://orcid.org/0009-0002-2696-0766 , Guayaquil; Ecuador.
2
Centro Nacional de Electromagnetismo Aplicado: Universidad de Oriente; lilianag@uo.edu.cu ; https://orcid.org/0000-0002-1282-
3392 , Santiago de Cuba; Cuba.
Health issues caused by the effects of cyanotoxins result
from changes in the environment of cyanobacteria, which
induce alterations in their organic composition, stimulating
the production of highly harmful molecules capable of
affecting living organisms, with serious environmental
implications and economic repercussions for societies [2].
To date, more than 50 genera of cyanobacteria with toxic
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Pag. 12
potential have been described, making it relevant to
understand their dynamics in ecosystems, triggering factors,
their presence in water and food, and the consequences of
exposure to different concentrations of these cyanotoxins,
as all of these are associated with risks to human life [3]. In
this regard, the One Health approach considers their impact
on the human trophic web and their entry routes,
necessitating the responsible handling of potable water and
fresh food with high toxic loads [4]. Responsible production
and consumption of food are essential to ensure the health
of humans and animals, as well as the long-term health of
the environment. Without good practices along the food
value chain, food can become a major vehicle for the
transmission of microbiological and chemical hazards [5].
Foodborne diseases are caused by the consumption of
contaminated food and encompass a wide group of diseases
caused by enteric pathogens, parasites, chemical
contaminants, and biological toxins. These diseases reduce
societal productivity, impose substantial pressure on the
healthcare system, and reduce economic output due to
decreased consumer confidence, food losses, and disruption
of access to domestic and export markets, affecting trade
and tourism, and threatening food security [6].
Especially populations that do not properly manage the risks
caused by constant interaction with cyanotoxins; do not
have or do not apply regulations, do not control established
maximum permissible limits, or do not even pay attention
to this issue, will have a latent cause of natural health
damage in these toxic events [1]. This study focuses on
systematizing scientific literature on the health impacts of
cyanobacteria due to the presence of cyanotoxins,
specifically in freshwater bodies and contaminated fresh
foods, all being publicly accessible resources essential for
sustaining life, development, and social interaction.
However, it is important to consider that the ubiquity of
these microorganisms makes any ecosystem and food
vulnerable.
Moreover, this work allows a recap of key aspects related to
the presence of cyanotoxins, including management
initiatives during risk events, to safeguard the integrity of
living beings, with an emphasis on human health; focusing
on documenting triggering factors, present toxins,
associated cyanobacteria species, and the main health
impacts on humans after exposure to toxicological
elements, such as a conflicting experience due to chronic
exposure, and the presence and/or accumulation through the
food chain.
2. Materials and Methods
The methodological management implemented for the
development of this study is based on a narrative review of
research published in high-impact institutional repositories,
as well as relevant academic publications on the topic. To
obtain the documents, a general technical search was
conducted using scientific databases of interest: Crossref
and Google Scholar, with specific descriptors; in addition to
targeted searches on PubMed, Scielo, and Scopus,
considering authors previously identified for their
contributions to the topic. The publication limits consider
the last 10 years of documentary validity, which was
delimited with the intention of obtaining a completely
updated source of information on the implications of the
presence of cyanotoxins in water and fresh food. The
descriptors or keywords considered were: cyanotoxins,
toxic cyanobacteria, including health risks as a
complementary phrase.
Publications in Spanish, English, and Portuguese were
included, corresponding to indexed articles, theses, books,
and scientific reports. Once the information was
recapitulated, a semi-structured analysis of the
contributions of the research was carried out, regarding the
impact of cyanotoxins on human health, and the
management of drinking water and food with toxicological
loads, considering the One Health approach.
3. Cyanotoxins and Their Conflict Relationships in
Societies
The proliferation of cyanobacteria in water and food is
largely due to anthropogenic effects such as eutrophication
and even the presence of industrial and agricultural
pollutants, as well as issues related to domestic sanitation
[7], without minimizing the effects of climate change.
Urban and sociodemographic expansion promotes a
considerable environmental impact with a direct climate
repercussion by overwhelming the structural sanitation of
large cities [8]. The discharge of wastewater that has not
found new territorial fractions for proper treatment,
especially in the mass production of food, directly tied to
the need to meet consumption demands, simply increases
the indiscriminate elevation of harmful elements for health
with high loads of chemicals such as nitrogen and
phosphorus [9]. This leads to secondary events such as the
development of phytoplankton blooms, which extend to
reservoirs that supply water, later used for the operational
development of various activities, notably agroindustry [4].
The situation becomes a vicious cycle produced by the lack
of good practices and the failure of control mechanisms and
management models.
The impact of cyanobacteria blooms and the presence of
cyanotoxins has been demonstrated [10], in most cases
being associated with a high occurrence of specific health
problems, driven by conflictive organisms that in certain
proportions can cause gastrointestinal, dermatological, and
even neurological system disorders as one of their main
consequences [11].
According to Almeida [12] certain species of cyanobacteria
in the animal kingdom can produce cyanotoxins, although
they are not sufficient causes to affect the health of living
beings if interacting with a tolerable load of toxins;
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Pag. 13
however, once present, they constitute an imminent danger.
Even so, industrial activities facing all these natural
ecosystem conditions intensify the production of
cyanotoxins, causing liver damage, cytotoxicity, and even
neurotoxicity in part of the population [13] and in many
cases, primary healthcare is not culturally prepared to face
the situation, associating it with other toxic agents; this is
more noticeable in places where risk perception is null or
low.
In the case of exposure, it not only includes the consumption
of intoxicated animals through the trophic chain or
contaminated water, but there are also cases where the
development of recreational activities in water bodies is an
influential contact factor for the impact of cyanotoxins on
health[2], [14].
Evidently, states that do not properly manage and address
the liquid effluents of water bodies contribute to the increase
of toxicological loads [15] through eutrophication and,
consequently, the occurrence of cyanobacteria blooms [8].
In Latin America, for example, phytoplankton blooms in
reservoirs are a recurring problem that influences the
effective management of drinking water, even altering its
properties by not using effective technology to eliminate
cyanobacteria and cyanotoxins, a situation that worsens
after its supply [13].
4. Cyanotoxins: Types and Effects on Human Health
Cyanobacteria toxins are harmful components to living
organisms; they comprise a heterogeneous group of
chemical compounds with high toxicological loads and
multiple metabolic representations [8]. According to the
findings of Menescal [15] these substances can develop in
all phases of cell growth, as they are released when
cyanobacteria cells break (lysis), remaining in the water for
many weeks, depending also on environmental conditions.
Although the productive occurrences of these toxic
substances have not been clarified by science, a plausible
hypothesis is their role in herbivore protection, where not
all cyanobacteria blooms are toxic [16]; however, they can
be harmful.
Regarding toxicological classification, cyanotoxins can be:
1) hepatotoxins, capable of causing liver injuries due to
morphological and functional alterations in hepatocytes,
promoting autophagy and cell proliferation depending on
the amount and duration of exposure; 2) neurotoxins, which
cause lethal acute intoxication and interfere with nerve
impulse connections, potentially causing muscle paralysis
and subsequently respiratory issues; and 3) dermatotoxins,
generally not lethal but manifesting with high irritation and
inflammatory process alterations in the body [12].
Therefore, understanding the applied action of hepatotoxins
and neurotoxins revolves around intoxication, where
science strives to effectively treat these compounds to avoid
health consequences [17]. Dermatotoxins are also important
cases of intoxication in swimmers in coastal waters,
highlighting debromoaplysiatoxins and lyngbyatoxin-a
[10]. Additionally, there is a segment called
lipopolysaccharide (LPS), which plays a significant role in
toxicology [11]. Lipopolysaccharide (LPS) or endotoxin is
the major component of the outer membrane of Gram-
negative bacteria, playing an important role in activating the
immune system by constituting the most important surface
antigen of these bacteria. LPS is composed of a lipid and a
glycosidic region with separate and/or synergistic functions,
making this molecule one of the most complex virulence
factors to understand [18].
Animal experiments are noteworthy for validating the
behavior of the mechanism of action of cyanotoxins; in this
regard, there are multiple deviations that demonstrate direct
risks to humans as they are completely different matters
[14]. Moreover, there is a latent health risk that transcends
into alterations attributable to algal blooms, whether from
drinking water sources, consumption of contaminated food,
direct interaction in coasts or rivers usually used for
recreation, as well as other characteristic factors such as age
or pathological history [19].
Cyanotoxins have been studied for their impact on drinking
and recreational waters. Painefilú [8] in his report shows
that recreational exposure is linked to mild and self-limiting
symptoms that do not require medical consultation; in
contrast, Miglione et al. [20] clarifies that the nonspecific
symptomatology of these situations can lead to a
misdiagnosis, with cases reported in his study frequently
directing to gastrointestinal incidents, irritative factors in
the eyes or respiratory tract, and dermatological and
pulmonary symptoms, where scientific evidence shows that
the most severe are hepatic types.
Recapping health effects, historically, the first case of
cyanotoxin intoxication was from interacting with
contaminated waters of the Ohio River in the United States
in 1931. Subsequently, in 1959, a recreational exposure
occurred in Saskatchewan, Canada, noted as one of the 10
provinces among the 13 federal entities of this country that
demonstrate its incidence since the last century [14].
In Latin America, the first acute microcystin intoxication
with demonstrated hepatotoxicity in individuals was due to
water contamination, affecting 116 people, associated with
recreational exposure within the Uruguay River reservoir in
2007 and later on the beaches of the Río de la Plata in
Montevideo in 2015 [14]. Other intermediate events have
been recorded.
Thus, direct exposure occurs in areas with higher population
density, which in most cases manifests as health alterations,
either acute or chronic [9], always due to accidental
ingestion of resources such as contaminated water and food,
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Pag. 14
skin contact, and even indirect inhalation of cyanotoxins
that can remain suspended in tiny aerosol droplets [21].
Therefore, determining the incidence of these components
in people with prolonged contact is a precedent for
preventing health alterations [22].
In this regard, multiple cases of diseases in humans and
sentinel animals have been documented due to contact with
contaminated water and fresh food, with incidences of liver
cancer, as in some regions of China, and even death from
direct contact with microcystins [23]. The most dangerous
intoxication was documented in 1996 in Brazil, where 100
out of 131 individuals on dialysis developed acute liver
failure due to the presence of cyanotoxins in the water; 52
of these people died [23]. In summary, all research
demonstrates that understanding the effects of cyanotoxins
is of great interest for maintaining and balancing public
health, and if not considered, can lead to significant mass
consequences, historically affecting a broad segment of the
population according to the situational context where these
intoxication events occur.
5. Vulnerability to the Impact of Cyanotoxins
Urbanization efforts, in line with the increase in industrial,
agricultural, and livestock activities, have a significant
impact on environmental pollution. Water resources
directly affect human health [24]. Consequently, exposure
to certain environmental contaminants can even lead to
neurodegenerative diseases [9].
Various human activities in urban and rural areas generate
nutrient accumulation; this organic load promotes
eutrophication, increasing bacterial contamination that can
disrupt trophic networks [25] and compromise the quality
of fresh food from aquatic ecosystems. Eutrophication leads
to the uncontrolled growth of algae and photoautotrophic
bacteria, namely cyanobacteria [19]. Blooms increase the
biomass of cyanobacteria; the loose masses that form can
also cause problems in aquatic ecosystems [9].
According to Federici et al. [26] 80% of cyanobacteria
blooms in continental waters are toxic, affecting multiple
species. For instance, the deaths of cattle, dogs, horses, and
even large animals like the 300 elephants that died in
Botswana in 2020 were attributed to neurological problems
after consuming water contaminated with cyanotoxins [26].
Given these conditions, it is prudent to reference the
arguments of Condor and Feliciano [10] who highlight the
existence of a great diversity of toxins produced by different
genera of cyanobacteria, whose production also depends on
environmental factors such as nutrients and temperature,
among others. Additionally, the described and currently
understood toxicity mechanisms are also diverse, ranging
from hepatotoxic effects associated with
cylindrospermopsins, nodularins, and microcystins;
neurotoxins (saxitoxin, anatoxin-a) and dermatotoxins
(lyngbyatoxin-a, aplisiatoxin), and LPS [27]. Although
science focuses heavily on neurotoxins due to their greater
degenerative incidence and the environmental and health
risks they represent, and hepatotoxins due to their greater
distribution, incidence, and concomitance with other factors
causing liver diseases, they are a priority according to ONU
recommendations [28].
This suggests the necessary attention not only to aquatic
animals but also to terrestrial life due to the bioaccumulation
of cyanotoxins in the food chain [22].
It is a matter of extreme care; altering the functionality of
the liver and muscles of various animal species, which are
subsequently consumed by humans, can result in
concentrations that exceed tolerance levels with a high
toxicological load that is difficult to tolerate.
6. Classification of Cyanotoxins, Chemical Structure,
and Mechanisms of Action
The essential characteristic of cyanobacteria concerning
health hazards depends on their ability to synthesize
cyanotoxins. Approximately more than 150 genera and
around 2,000 species of cyanobacteria exist [13], with only
a few species being toxic. Cyanotoxins are produced in the
cytoplasm of these microorganisms, and they release their
composition through cell lysis [17], which is a result of
physiological processes related to cellular senescence due
to pathological causes related to cellular stress, such as the
use of algicides like copper sulfate and hydrogen peroxide.
Additionally, the production and potency of cyanotoxins
vary, necessitating constant monitoring of species with
toxic potential to prevent damage or health alterations in
humans and at-risk ecosystems [17].
The main cyanotoxins can be segmented according to their
mechanisms of action in multicellular organisms and
classified into three groups: i) hepatotoxins: microcystins
and nodularins; ii) neurotoxins: anatoxin, homoanatoxin-a,
guanitoxin, and saxitoxin; and iii) cytotoxins:
cylindrospermopsin. Additionally, dermatotoxins include
elements like lyngbyatoxin-a and debromoaplysiatoxin, the
latter described as agents causing dermatitis.
Microcystins are heptapeptides whose target organ is the
liver [9]. Anatoxins, on the other hand, are alkaloids
structurally similar to acetylcholine, characterized by
activating cholinergic receptors and keeping them activated
for an indefinite time [17]. Furthermore, within the group of
alkaloids are saxitoxins, which act on sodium channels,
blocking the transmission of nerve impulses. Anatoxins and
saxitoxins are considered neurotoxins because they affect
the nervous system. They alter different nerve pathways,
causing paralysis and respiratory failure, which can lead to
death [9].
Hepatotoxin
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The study of these toxins is crucial for understanding their
effects and developing regulatory strategies among
ecosystems, especially those vulnerable to blooms of toxic
cyanobacteria that produce hepatotoxins. Hepatotoxins
(microcystins and nodularins) are produced by about eleven
genera. (Table 1):
Table 1. Genera of Cyanobacteria Producing Hepatotoxins
Anabaenopsis
Nodularia
Planktothrix
Dolichospermum
Nostoc
Pseudanabaena
Hapalosiphon
Microcystis
Synechocystis
Lyngbya
Oscillatoria
Source: Taken from Silva [17].
These cyanobacteria are the most common in freshwater
bodies [17], which raises concerns about these toxins. They
are cyclic peptides formed by seven amino acids, five of
which are D-amino acids and two L-amino acids. This
composition determines a series of variants based on the L-
isomeric amino acids present in the cyclic chain. To date,
more than 100 variants of microcystins (MCs) have been
described. These variants arise from different combinations
of amino acids and various other alterations (such as
methylation or demethylation of several functional groups).
The most common variants are microcystin-LR (leucine-
arginine), microcystin-RR (arginine-arginine), and
microcystin-YR (tyrosine-arginine) [17].
Neurotoxins
Neurotoxins affect the nervous system and are known for
their rapid action, which in the worst cases, leads to death
by respiratory failure within minutes of entering the body
[21]. Their neurotoxic alkaloids act on cholinergic synapses
or voltage-dependent ion channels, directly blocking nerve
impulses in skeletal muscles, causing muscle paralysis and
death by asphyxiation. The genera of cyanobacteria that
produce neurotoxins are listed in Table 2:
Table 2. Genera of cyanobacteria producing neurotoxins.
Anabaenopsis*
Hapalosiphon*
Pseudanabaena*
Dolichospermum*
Oscillatoria*
Sphaerospermopsis
Chrysosporum
Planktothrix*
Trichodesmium
Legend: (*) genera with species producing hepatotoxins. Source: Taken
from Silva [17]
Neurotoxins can vary in their chemical structure. Anatoxin
(or anatoxin-a) is a bicyclic secondary amine alkaloid
structurally related to homoanatoxin-a, differing only in the
presence of a propionyl group instead of an acetyl group
[17]. On the other hand, guanitoxin, formerly known as
anatoxin-a (S), is a methylphosphoryl ester of N-
hydroxyguanidine and is the only known natural
organophosphate. According to this classification,
intoxication with this bioactive metabolite leads to
progressive clinical signs of muscle fasciculations, reduced
movement, abdominal breathing, cyanosis, seizures, and
death, which can occur within minutes to a few hours,
depending on the affected animal species and the amount of
toxin ingested [17].
Neurotoxins act as postsynaptic blockers of nicotinic and
cholinergic receptors by irreversibly binding to
acetylcholine receptors, overstimulating muscle
contractions and causing muscle exhaustion [17]. Despite
various studies on the toxicology of this neurotoxic
alkaloid, some authors believe that the available database is
not sufficient to determine a tolerable daily intake level due
to the high level of uncertainty regarding long-term
exposure.
6.2. Cytotoxins
Among the cytotoxins produced by cyanobacteria,
cylindrospermopsin is the most well-known [29]. This toxic
alkaloid was first described in 1979, when 148 people were
hospitalized with symptoms of hepatotoxicity on Palm
Island, associated with a bloom of the cyanobacterium
Cylindrospermopsis raciborskii in a drinking water
reservoir. Additionally, other species of cyanobacteria
producing cylindrospermopsins have been identified,
including: Aphanizomenon ovalisporum (reclassified as
Chrisosporum), Aphanizomenon flos-aquae, Umezakia
natans, Rhaphdiopsis curvata, Anabaena bergii, Anabaena
lapponica, and Lyngbya wollei [29].
The widespread distribution of cylindrospermopsin-
producing species, along with the invasive nature of the
primary toxin producer (C. raciborskii), poses a significant
global water management issue [30]. It consists of a
tricyclic alkaloid formed by a guanidine group combined
with a hydroxymethyluracil. Due to its zwitterionic nature
(electrically neutral chemical compound), this cyanotoxin is
highly soluble in water. Additionally, natural structural
variants have been identified, such as 7-epi-CYN (7-
epicylindrospermopsin) and 7-deoxi-CYN (7-deoxy-
cylindrospermopsin) [30].
These elements interfere with various metabolic pathways,
triggering hepatotoxic, general cytotoxic, and neurotoxic
effects, in addition to having carcinogenic potential [17]
Toxicity is mediated by the inhibition of glutathione,
protein synthesis, and cytochrome P450, with the uracil and
hydroxyl moiety at C7 crucial for toxicity. Intoxication can
cause damage to the liver, kidneys, thymus, lungs, stomach,
and heart [17]. Traditionally, cyanotoxins have been
classified according to their chemical composition into
peptides, alkaloids, and the presence of lipopolysaccharide
(LPS), or eventually according to their toxic derivatives:
hepatotoxins, neurotoxins, or dermatotoxins [30] (Table 3).
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Pag. 16
Table 3. Organs affected by recognized toxic metabolic
compounds according to the existing classification of
cyanobacteria.
Cyanotoxins
Primary organ or
process affected
Genera of
cyanobacteria
associated
Microcystins
Liver
Anabaena, Nostoc,
Oscillatoria,
Planktothrix,
Anabaenopsis,
Microcystis
Nodularins
Liver
Nodularia
LPS
Cell, cytotoxicity
Any cyanobacteria, as
it is a component of
the Gram-negative
bacterial membrane
Anatoxin-a
Cholinergic
connections
Oscillatoria,
Anabaena,
Aphanizomenon,
Planktothrix
Aplysiatoxins
Skin
Lyngbya, Schizothrix,
Planktothrix
(Oscillatoria)
Cylindrospermopsins
Liver
Cylindrospermopsis,
Aphanizomenon,(Ume
zakia)
Lyngbyatoxin-a
Skin, gastrointestinal tract
Lyngbya
Saxitoxins
Neuronal
connections, nerve
impulse
transmission
repression
Lyngbya,
Aphanizomenon,
Cylindrospermopsis,
Anabaena
Source: Taken from Andrinolo and Sedan [30].
If one reviews Table 3, a widespread occurrence of deferred
toxins with analogous combinations of structural order can
be perceived. Andrinolo and Sedan [30] in this sense,
explain that these analogous segments are known
collectively as toxins according to an STXs classification
that groups all their limitations, and the same applies to the
MCs, which are noted for maintaining possible variants
only in some of them. The toxicological relevance for the
environment lies in the typical variations in toxicity from
raw cell states, with a higher incidence in biological assays
involving rodent species and aquatic animals such as fish or
crustaceans; this differentiation can be attributed to toxins
that are distinguishable by a combination of chemical,
biochemical, and immunological effects [22].
Therefore, evaluations of one or multiple toxins are not
sufficient to segment the risk generated by the combination
of cyanotoxins in a bloom, since these issues point to a
conflict among bioassays because they fail to completely
rule out elements that can be used complementarily in the
analysis; leading to a false negative diagnosis when
evaluations are applied to bodies of water or food,
potentially interacting with these elements [30].
6.3. Consequences of the presence of cyanotoxins
Throughout this presentation, multiple types of health
conditions have been highlighted that can intensify due to
factors that transcend the growth of cyanotoxins,
attributable to transcribed levels of genes (peptide
synthetase and polyketide synthase) [30]. This condition
leads to an increase in these toxins without inhibition assays
being able to alter them [31], hence the need to use costly
assays for their detection in many cases. Additionally, the
effects of components such as iron, while not directly
influencing cyanotoxin production, do increase synthesis
and impact toxicity levels [31].
On the other hand, while toxins have target organs or
processes, they are capable of affecting or altering other
organs and/or processes. In this regard, microcystins
interact with the liver and are directly considered
hepatotoxins, but they can also affect other organs such as
the kidneys, lungs, and intestines [27]. Exposure to these
types of components through direct contact with the eyes,
mucous membranes, and even the ear, as well as ingestion
of contaminated water and inhalation, constitutes a risk that
can leave lasting health consequences for the individual
[24].
In general, two types of intoxications are described: acute
intoxication with microcystins causing significant hepatic
damage, affecting the cytoskeleton by directly generating
necrosis that alters hepatocytes [24] and chronic
intoxication with microcystins, which has a wider range of
symptoms and cannot go unnoticed; furthermore, this type
of pathology is associated with high rates of liver cancer
promotion [24]. At certain times, cyanobacterial blooms can
produce highly harmful toxins as documented throughout
this report, highlighting the impact of microcystins on
health by affecting liver function [31].
Therefore, emphasis is placed on the importance of prior
information before managing essential life resources, such
as water quality, as an essential precursor to favoring the
proliferation of cyanobacteria, which varies depending on
whether a toxin-producing organism is involved in bodies
of water used for consumption [32]. Typically, these
organisms interact with water and calcium carbonate,
resulting in pH values above 8.5 to 9.1, associated with high
MC concentrations (≥5 µg/L). In this context, it is important
to consider that light intensity and pH are triggering factors
for the proliferation of cyanotoxins in vitro [32]. However,
the influence of conductivity, temperature, TN:TP ratio, and
trophic index [33]; also stand out; these are essential aspects
to consider during molecular analysis of samples collected
in different ecosystems [23].
7. Discussion
It can be said that regulations for studies regarding the
proper management of water and fresh foods require the
supervision of environmental components. Research such
as that by Miglione et al. [20] proposes implementing
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Pag. 17
electrochemical biosensors that have an applicable
proportion for detecting natural toxins such as cyanotoxins.
This has become an effective resource that has increased in
the last decade, providing valuable tools to understand the
dynamics of these toxins in ecosystems, their impact on the
food chain, and their health consequences.
The presence of cyanotoxins in water and fresh foods, and
their passage into the gastrointestinal tract, implies
bioaccessibility [16]. This is a crucial aspect when
evaluating the risks of exposure, which can be direct
through the consumption of fresh or minimally processed
foods, with attention needed on the effects of cooking
processes [20]. The ingestion of foods contaminated with
cyanotoxins is the most common route of chronic exposure
to them, following the ingestion of contaminated drinking
water. However, the presence of cyanotoxins in food does
not guarantee absorption, as this depends on several factors
such as whether the toxins are in their free form or not [16],
in addition to consumer susceptibility and toxic load;
whether consumption is direct or through vectors; and
whether there has been synergy with other exposure routes
or toxins, which could increase the toxic load.
From minimally processed to highly processed foods, they
undergo processes such as brining or other substances
and/or cooking before ingestion. Heat can cause significant
changes in the food matrix. In general, the effect of food
processing depends on different aspects such as the type of
processing, the type of compound considered, the
composition and structure of the matrix, and the potential
presence of other components that could affect the
absorption of the mentioned compound [34]. Therefore,
recent studies emphasize the importance of correlating in
vivo and in vitro data on food digestion.
Although static in vitro models are simplified and do not
reproduce all dynamic aspects of the gastrointestinal tract,
only the main conditions such as pH, enzymes, and salt
concentrations, these models are increasingly useful for
predicting in vivo digestion in some cases and offer
numerous advantages in evaluating the breakdown
dynamics of some toxins. Some studies on marine toxins,
for example, have been conducted using static in vitro
models. The ideal in vitro digestion technique should
provide accurate results quickly and serve as a tool for rapid
analysis of food models with different structures and
compositions. However, the most important thing is not just
to understand these aspects, but to use science for risk
management and prevention, taking actions based on these
results to preserve the health of people who constantly
interact with elements with high toxicological burden. In the
long term, the implications of not doing so could be
irreversible and even difficult to control.
8. Conclusions
The exploration of new development models must uphold a
commitment to producing safe food and drinking water free
from toxins that can harm the human body; this must be
promoted through ecosystem conservation. Environmental
sustainability is crucial for all productive schemes, achieved
through management practices that prioritize the care and
conservation of water resources, ensuring quality of life.
Studies on water quality do not always encompass
comprehensive analyses, often focusing on
physicochemical properties while neglecting cellular and
molecular bioindicators, as well as microbiological analyses
crucial in current environmental conditions. Hence, there is
a need for greater research into the presence of cyanotoxins
in Latin American water bodies, especially in countries
lacking regulations or controls ensuring safe water supply
and availability of cyanotoxin-free food.
Governments worldwide should conduct continuous long-
term monitoring and, if necessary, strengthen intervention
efforts, considering not only the presence of cyanotoxins in
aquatic ecosystems but also their impact on environmental
services and the food chain. This affects not only the health
of aquatic organisms that serve as fishery resources but also
terrestrial organisms that form the dietary base for many
communities.
Effectively managing risks associated with cyanotoxin
presence hinges on implementing systematic monitoring
schemes. Therefore, promoting accurate and appropriate
assessment involving scientific input is crucial to ensure
precise and reliable analyses that reflect the true state of
ecosystems in each context, enabling measures to preserve
human, animal, and environmental health.
Raising awareness among decision-makers, along with
training and capacity building in research and management,
is crucial in any management initiative to enhance
awareness of this emerging risk, which often compromises
not only health but also lives.
The food industry must implement control and monitoring
strategies to prevent contamination of drinking water and
fresh or minimally processed foods. Developing risk
management models is critical to ensuring the supply of safe
food and safeguarding consumer health.
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