Metabolite Of Aflatoxin B1 Research Articles

Potential Harmful Effects of Aflatoxin M1 in Milk and Milk Products and Novel Methods to Reduction of Aflatoxin M1: A Review

Dairy products are rich sources of vitamins, proteins and calcium that are vital to the human body. Aflatoxin M1 is a hydroxylated metabolite of aflatoxin B1. The presence of this toxin in milk has caused serious concern among nutritionists. Consumption of aflatoxin-contaminated milk (AFM1) may lead to serious health problems in humans. AFM1 causes various cancers such as liver cancer, damage to the nervous and DNA, as well as mutagenicity and teratogenicity. In reducing the amount of aflatoxin in the product, with does not affect the milk quality is of particular importance. Absorption and restructuring methods such as yeast, lactic acid (bacteria), enzymes, ozon, and cold plasma have been used for this purpose. In this study, they have been studied on aflatoxin M1 and toxicology besides reducing method for aflatoxin M1.

Chemoprotective Effects of Xanthohumol against the Carcinogenic Mycotoxin Aflatoxin B1.

The present study addresses the chemoprotective effects of xanthohumol (XN), a prenylated flavonoid found in the female inflorescences (hops) of the plant Humulus lupulus L., against the carcinogenic food contaminant aflatoxin B1 (AFB1). The chemical reactions of XN and its derivatives (isoxanthohumol (IXN), 8-prenylnaringenin (8-PN), and 6-prenylnaringenin (6-PN)) with the AFB1 metabolite, aflatoxin B1 exo-8,9-epoxide (AFBO), were investigated in silico, by calculating activation free energies (ΔG‡) at the Hartree–Fock level of theory in combination with the 6-311++G(d,p) basis set and two implicit solvation models. The chemoprotective effects of XN were investigated in vitro in the metabolically competent HepG2 cell line, analyzing its influence on AFB1-induced cytotoxicity using the MTS assay, genotoxicity using the comet and γH2AX assays, and cell cycle modulation using flow cytometry. Our results show that the ΔG‡ required for the reactions of XN and its derivatives with AFBO are comparable to the ΔG‡ required for the reaction of AFBO with guanine, indicating that XN, IXN, 8-PN, and 6-PN could act as scavengers of AFBO, preventing DNA adduct formation and DNA damage induction. This was also reflected in the results from the in vitro experiments, where a reduction in AFB1-induced cytotoxicity and DNA single-strand and double-strand breaks was observed in cells exposed to combinations of AFB1 and XN, highlighting the chemoprotective effects of this phytochemical.

Detoxification of Aflatoxin M1 in Milk by Lactic Acid Bacteria

Background: Aflatoxin M1 is a highly toxic and carcinogenic compound which is found in milk and milk products and it is a hydorxylated metabolite of Aflatoxin B1. When the dairy animal digested AFB1 contaminated feed, it is changed to aflatoxin M1 and transferred to tissues and milk. Aflatoxin M1 is less carcinogenic than AFB1, but it is acutely hepatotoxic as AFB1. Liver is their main target organ in the body. It has been calculated approximately that 0.3- 6.2% of presented AFB1 in animal feed transferred as aflatoxin M1 in milk. Occurrence of AFM1 in milk and milk products is a big concern. Therefore, several countries have standardized the maximum levels of AFM1 in milk and milk products. Methods: In this experiment, the ability of yoghurt bacteria to degrade AFM1 levels in milk and yoghurt were analysed. The starter culture of yoghurt contains Streptococcus thermophilus and Lactobacillus delbrueckii subsp. Bulgaricus (1:1). The experiment is carried out in Glasgow Caledonian University, department of life science in 2010. Result: These bacteria showed the higher binding ability between 90- 100% in milk samples whereas no considerable reduction was observed in yoghurt samples. In some yoghurt samples, an increase of AFM1 level was detected but in overall, concentration of AFM1 was stable in yoghurt. Also, the fat content of milk and yoghurt did not have any negative or positive effect on the concentration of AFM1 in milk and yoghurt.

A survey on the occurrence of aflatoxin M1 in raw milk samples in Bafq and Bahabad, Iran

Aflatoxins are a group of mycotoxins mostly produced by the fungi called Aspergillus flavus, Aspergillus parasiticus, and Aspergillus nomium. Aflatoxin M1 (AFM1) is the major metabolite of aflatoxin B1 and is a hepatotoxic and carcinogenic toxin. The aim of this study was to determine the level of contamination of cow's milk with aflatoxin M1 in Bafq and Bahabad. For this study, samples of raw cow's milk were collected randomly from milk collection centers around the city of Bafq and Bahabad from March to April. The determination of aflatoxin M1 levels was based on the ELISA method. Contamination was observed in 100% of milk samples. According to the results of the study, the rate of contamination with aflatoxin M1 in 43.3% of milk samples was above the acceptable level (50 ng/L) in Iranian national standard. It is concluded that further monitoring of milk production should be carried out in the spring and winter seasons.

Prevalence and associated factors of breastmilk aflatoxin M1 levels in mothers from Banke, Nepal

Aflatoxin M1 (AFM1) is the hydroxylated metabolite of aflatoxin B1 (AFB1) formed in the liver of mammals and subsequently excreted in breastmilk (BM) of mammals. Humans are exposed to AFM1 mainly through the consumption of aflatoxin contaminated milk and foods. Determining levels of AFM1 is of significant public health importance due to the risk of exposure to breastfeeding infants. The objective of this study is to determine the prevalence of AFM1 in BM and assess factors associated with BM AFM1 levels in mothers. Data, collected between July 2015 and July 2017, were derived from the Aflacohort study (n = 1675) in Banke district, of Province 5 in the south-west region of Nepal. AFM1 was analyzed using ultra-high-performance liquid chromatography with a lower limit of detection of 0.04 ng/L (ng/L). Multivariate linear and quantile regression models were used to examine the relationship of factors with AFM1, including mother's age, food consumption and body mass index, as well as, seasonality and wealth quintiles. Approximately 94% of BM samples had detectable levels of AFM1 (geometric mean 0.78 ng/L and range 0.04 ng/L to 315.99 ng/L). The consumption of particular foods such as yogurt, milk, hydrogenated oil and ripe pumpkin was positively associated with BM AFM1 levels (p-value <0.05), while consumption of legumes was associated with lower BM AFM1 levels (p-value <0.05). Seasonal influences were significant, with BM collected in the pre-winter and winter seasons exhibiting significantly higher AFM1 levels compared to the spring (p-value <0.05). These results suggest near-ubiquitous presence of aflatoxin in the food supply of this part of Nepal, and possible exposure of AFM1 to infants through BM of mothers. The findings justify integrated strategies across the value chain and at household level to identify dietary sources of aflatoxin exposure, proper post-harvest management and monitoring for aflatoxin control and mitigation.

Unveiling the spatial distribution of aflatoxin B1 and plant defense metabolites in maize using AP-SMALDI mass spectrometry imaging.

In order to cope with the presence of unfavorable compounds, plants can biotransform xenobiotics, translocate both parent compounds and metabolites, and perform compartmentation and segregation at the cellular or tissue level. Such a scenario also applies to mycotoxins, fungal secondary metabolites with a pre-eminent role in plant infection. In this work, we aimed to describe the effect of the interplay between Zea mays (maize) and aflatoxin B1 (AFB1) at the tissue and organ level. To address this challenge, we used atmospheric pressure scanning microprobe matrix-assisted laser desorption/ionization mass spectrometry imaging (AP-SMALDI MSI) to investigate the biotransformation, localization and subsequent effects of AFB1 on primary and secondary metabolism of healthy maize plants, both insitu and from a metabolomics standpoint. High spatial resolution (5µm) provided fine localization of AFB1, which was located within the root intercellular spaces, and co-localized with its phase-I metabolite aflatoxin M2. We provided a parallel visualization of maize metabolic changes, induced in different organs and tissues by an accumulation of AFB1. According to our untargeted metabolomics investigation, anthocyanin biosynthesis and chlorophyll metabolism in roots are most affected. The biosynthesis of these metabolites appears to be inhibited by AFB1 accumulation. On the other hand, metabolites found in above-ground organs suggest that the presence of AFB1 may also activate the biochemical response in the absence of an actual fungal infection; indeed, several plant secondary metabolites known for their antimicrobial or antioxidant activities were localized in the outer tissues, such as phenylpropanoids, benzoxazinoids, phytohormones and lipids.

Validation of I'screen AFLA M1 Milk for Detection of Aflatoxin M1 in Raw Bovine Milk and Powdered Milk: AOAC Performance Tested MethodSM 072002.

Aflatoxin M1 (AFM1) is the major metabolite of Aflatoxin B1 (AFB1) and can be found in the milk of animals fed with feed containing AFB1. The frequency of occurrence of AFM1 in milk has led to the development of specific quantitative methods of analysis to mitigate the risk of adversely affecting human health. To demonstrate that the I'screen AFLA M1 Milk ELISA kit can quantify AFM1 in raw bovine milk and powdered milk. Assay performance was evaluated studying lot-to-lot consistency, assay stability, robustness, and possible interferences of related molecules. Raw bovine milk samples spiked at 0, 5.0, 20, 50, 100, and 200 ng/L of AFM1 and powdered milk reference materials and spiked samples at 100 and 200 ng/L were tested to determine recovery, repeatability, and bias. LOD and LOQ were also determined for both matrices. High selectivity for AFM1 was demonstrated and performances were consistent, robust, and stable. The LOQ was validated at 5 ng/L for raw milk and 50 ng/L for powdered milk. Recoveries for spiked raw and powdered milk were 97-122%, with RSDr < 10%, and 106-111% for reference materials, with RSDr < 5%. The data collected validate the method as a selective, specific, sensitive, accurate, and precise tool for the analysis of AFM1 in raw bovine milk and powdered milk. We demonstrated that I'screen AFLA M1 is a reliable kit and a proper screening tool suitable for high analytical throughputs.

The Mechanism Underlying the Extreme Sensitivity of Duck to Aflatoxin B1

Most metabolites of aflatoxin B1 (AFB1), especially exo‐AFB1‐8,9‐epoxide (AFBO), can induce the production of reactive oxygen species (ROS) to vary degrees, causing oxidative stress and liver damage, and ultimately induce liver cancer in humans and animals. Duck is one of the most sensitive animals to AFB1, and severe economic losses are caused by duck AFB1 poisoning every year, but the exact mechanism of this high sensitivity is still unclear. This review highlights significant advances in our understanding of the AFB1 metabolic activation, like cytochrome P450s (CYPs), and AFB1 metabolic detoxification, like glutathione S‐transferases (GSTs) in poultry. In addition, AFB1 may have other metabolic pathways in poultry, such as the mutual conversion of AFB1 and aflatoxicol (AFL) and the process of AFBO to produce AFB1‐8,9‐dihydrodiol (AFB1‐dhd) and further metabolize it into detoxification substances. This review also summarized some exogenous regulatory substances that can alleviate AFB1‐induced oxidative stress.

Determination of Aflatoxin M1 in Liquid Milk, Cheese, and Selected Milk Proteins by Automated Online Immunoaffinity Cleanup with Liquid Chromatography‒Fluorescence Detection.

Aflatoxins are secondary metabolites produced by a number of species of Aspergillus fungi. Aflatoxin M1 (AFM1) is a hydroxylated metabolite of aflatoxin B1 and is found in the milk of cows fed with feed spoilt by Aspergillus species. AFM1 is carcinogenic, especially in the liver and kidneys, and mutagenic, and is also an immunosuppressant in humans. A high-throughput method for the quantitative analysis of AFM1 that is applicable to liquid milk, cheese, milk protein concentrate (MPC), whey protein concentrate (WPC), whey protein isolate (WPI), and whey powder (WP) was developed and validated. AFM1 in cheese, milk, and protein products is extracted using 1% acetic acid in acetonitrile with citrate salts. The AFM1 in the resulting extract is concentrated using RIDA®CREST/IMMUNOPREP® ONLINE cartridges followed by quantification by HPLC‒fluorescence. The method was shown to be accurate for WP, WPC, WPI, MPC, liquid milk, and cheese, with acceptable recovery (81-112%) from spiked samples. Acceptable precision for WP, WPC, WPI, MPC, liquid milk, and cheese was confirmed, with repeatabilities of 4-12% RSD and intermediate precisions of 5-13% RSD. Method detection limit and ruggedness experiments further demonstrated the suitability of this method for routine compliance testing. An international proficiency scheme (FAPAS) cheese sample showed that this method gave results that were comparable with those from other methods. A method for high-throughput, routine testing of AFM1 is described. The method was subjected to single-laboratory validation and was found to be accurate, precise, and fit-for-purpose. An automated online immunoaffinity cleanup HPLC‒fluorescence method for milk proteins, cheese, and milk was developed and single-laboratory validated. It allows for high-throughput analysis of AFM1 and can be used for the analysis of AFM1 in whey protein products.

The Occurrence and Risk Assessment of Aflatoxin M1 in Yoghurt Samples from Hamadan, Iran

Background: Aflatoxin M1 (AFM1) is a hepatocarcinogenic and hydroxylated metabolite of aflatoxin B1, detected in milk and milk products. Objectives: The aim of our research was to determine the incidence and risk assessment of AFM1 through the consumption of yoghurt in Hamadan province of Iran. Methods: Fifty yoghurt samples were gathered from various areas of Hamadan province, Iran and tested for AFM1 by ELISA technique. The estimated daily intake (EDI) and the liver cancer incidence of aflatoxin M1 were determined. Results: AFM1 was detected in 43 (86%) samples, (mean: 28.56 ng/kg; range: &lt;5-98.65 ng/kg). The level of AFM1 in 9 (18%) samples was above the maximum tolerance limit (50 ng/kg). The AFM1 intake through yoghurt consumption in various population groups ranged from 0.016 to 0.032 ng/kg bw/day in mean consumers and 0.019 to 0.046 ng/kg bw/day in high consumers. Conclusion: The AFM1 intake through yoghurt contributed a slight part from the overall incidence of liver cancer in the Iranian population. From the findings of the current study, it can be derived that although the high percentage of yoghurt samples in Iran proved to be contaminated with AFM1 contents, did not show a public health concern considering the European Commission (EC) and the Institute of Standards and Industrial Research of Iran (ISIRI) maximum limits.

Determination of aflatoxin M1 and deoxynivalenol biomarkers in infants and children urines from Bangladesh

The mycotoxins aflatoxin B1 (AFB1) and deoxynivalenol (DON) are found worldwide in crops and dietary staples. The prevalence and levels of these contaminants can vary greatly, and data in Bangladeshi food commodities are scarce. To characterize human exposure, we have conducted biomonitoring, analyzing AFM1 (a metabolite of AFB1) and DON levels in urines of adult cohorts in Bangladesh. Yet, AFM1 and DON occurrence has not been studied in the very young population of this country. Thus, the same methods, HPLC-FD for AFM1 and LC–MS/MS for DON analysis, were now applied to determine these biomarkers in urines of infants (n = 49) and young children (n = 105) in Rajshahi and Dhaka district. Overall, AFM1 and DON detection frequency was 43.5% and 33.4%, with 34.7% and 11.5% in infant and 47.6% and 39.4% in children urines, respectively. The mean AFM1 levels in all infants (9.1 ± 14.3, max 55.6 pg/mL) and children (8.8 ± 12.9, max 75.3 pg/mL) were not significantly different. The AFM1 mean level was slightly higher in Dhaka (9.4 ± 12.4) compared to Rajshahi (8.5 ± 13.9 pg/mL) district. The average DON level was about 2-fold higher in infant (3.8 ± 2.9, max 6.8 ng/mL) than children urines (1.6 ± 1.8, max 8.6 ng/mL), and higher in Rajshahi (2.1 ± 2.3 ng/mL) than Dhaka (1.4 ± 1.6 ng/mL) district. The biomarker-based estimated average daily DON intake (29.6 ± 108.3 ng/kg bw in infants and 36.4 ± 81.8 ng/kg bw in children) or the maximum exposure (560 ng/kg bw) do not exceed the current maximum provisional tolerable daily intake value of 1 µg/kg bw for DON, although DON exposure in infants and children is higher than that of Bangladeshi adults. The AFM1 urine levels in young children are somewhat lower than those found previously in adult cohorts in Bangladesh, but the frequent detection of this biomarker for AFB1 exposure raises further concerns, also for this vulnerable part of the population. Therefore, continuous surveillance for aflatoxins in Bangladeshi food commodities is clearly required, first to identify major sources of intake and then to reduce exposure.

Survey of aflatoxin M1 contamination of dairy products in Taiwan

Owing to their nutritional value, dairy products were popular in Taiwan. Aflatoxin M1(AFM1) was the metabolite of potential carcinogen aflatoxin B1 and found in dairy products. An analytical method using immunoaffinty column for extraction and HPLC for quantification was developed for AFM1. The detection limits for fresh milk (pasteurized milk), milk powder and drinking yogurt (0.002, 0.02 and 0.005 ppb, respectively) were 10 times lower than that in the former survey. The recoveries of AFM1 from fresh milk were 83.3 ± 2.9 and 89.5 ± 2.9% at 0.5 and 0.05 ppb spiked levels, respectively. Spiked 5 and 0.5 ppb AFM1 in milk powder, the recoveries were 86.0 ± 1.9 and 88.7 ± 1.9%, respectively. The recoveries of AFM1 from drinking yogurt were 99.9 ± 1.4 and 94.8 ± 3.2% at 0.5 and 0.05 ppb spiked levels, respectively. It was the first time AFM1 was tested in drinking yogurt in Taiwan in this survey, and the performance for detecting AFM1 in drinking yogurt was also evaluated through attending an international proficiency test. Our laboratory got a satisfactory result. In order to survey AFM1 contents in dairy products, 44 samples of fresh milk, 45 samples of milk powder and 24 samples of drinking yogurt were collected from supermarkets, convenience stores and drug stores located in 23 counties of Taiwan from June to August, 2002. The results showed that AFM1 was detected in 40 samples of fresh milk at 0.002∼0.083 ppb level. AFM1 was not found in all milk powders. AFM1 was detected in 3 samples of drinking yogurt, at the level of 0.007, 0.009 and 0.044 ppb. According to the food sanitary standard regulation in Taiwan, the action levels of AFM1 were 0.5 ppb, 5 ppb and not-detectable for fresh milk, milk powder and infant formula products, respectively. The 113 samples collected in this survey all met the regulation requirements.

Determination of aflatoxin M1 levels in Turkish White and Kashar cheeses made of experimentally contaminated raw milk

Aflatoxin M1 (AFM1) is the hydroxylated metabolite of aflatoxin B1 and may be found in milk and dairy products such as cheese. This study was aimed to determine the AFM1 levels in Turkish White and fresh Kashar Cheese which were produced with experimentally contaminated raw milk and to observe the change of AFM1 distribution in White cheese during ripening. For this purpose, AFM1 was added in concentrations of 0.25, 0.50 and 1.0 μg/L of milk and then, the cheeses were produced according to their technologies. Whey, boiling water, cheese and brine samples were examined for AFM1 residues. The quantitative analysis of AFM1 was performed by ELISA using the AFM1 test kit. The toxin remained as 42.87% and 34.73% in Turkish White and Kashar cheese samples, respectively. The change of AFM1 concentration during the White cheese ripening of 0-90 days was recorded as the average of 9.8%.

Aflatoxin M1 in milk and milk products marketed by local and industrial producers in Bishoftu town of Ethiopia

Aflatoxin M1 (AFM1) or milk toxin is a hydroxilated metabolite of aflatoxin B1 from a contaminated feed. This study investigated the occurrence of AFM1 in milk and milk products collected from Bishoftu town (one of the major milk producing place in Ethiopia). Milk (n = 108), cheese (82), yogurt (93) and butter (82) samples were collected both from industrial and local producers. From the 365 samples analyzed, 361 samples were positive for AFM1. Maximum value was in cottage cheese with a concentration of 5.580 ± 0.08 μg/kg and minimum was in butter of zero (Not detected) value. Comparing the mean level of AFM1 between the four dairy products; milk > cottage cheese > butter > yogurt. Considering the average daily intake of AFM1 obtained in this study and the current average milk consumption rate (19 L/year) in Ethiopian consumers, only adults are in the safe zone with TDI (Tolerable Daily Intake) of AFM1 (0.0002 μg/kg of body weight). But infants and young children might be more exposed to the toxin due to their higher consumption of milk and milk products in their diet.

Detoxification of Aflatoxin B1 Contaminated Maize Using Human CYP3A4.

Aflatoxin B1 (AFB1) is a mycotoxin produced by Aspergillus flavus (A. flavus). AFB1 is reported to have high thermal stability and is not decomposed by heat treatment during food processing. Therefore, in this study, knowing that AFB1 is metabolized by cytochrome P450 (CYP), our aim was to develop a method to detoxify A. flavus-contaminated maize, under normal temperature and pressure, using Escherichia coli expressing human CYP3A4. First, the metabolic activity of AFB1 by recombinant human CYP3A4 was evaluated. As a result, we confirmed that recombinant human CYP3A4 metabolizes 98% of AFB1. Next, we found that aflatoxin Q1, a metabolite of AFB1 was no longer mutagenic. Furthermore, we revealed that about 50% of the AFB1 metabolic activity can be maintained for 3 months when E. coli expressing human CYP3A4 is freeze-dried in the presence of trehalose. Finally, we found that 80% of AFB1 in A. flavus-contaminated maize was metabolized by E. coli expressing human CYP3A4 in the presence of surfactant triton X-405 at a final concentration of 10% (v/v). From these results, we conclude that AFB1 in A. flavus-contaminated maize can be detoxified under normal temperature and pressure by using E. coli expressing human CYP3A4.

In vitro hepatic aflatoxicol production is related to a higher resistance to aflatoxin B1 in poultry

A study was conducted to determine the cytosolic in vitro hepatic enzymatic kinetic parameters Vmax, KM, and intrinsic clearance (CLint) for aflatoxin B1 (AFB1) reductase [aflatoxicol (AFL) production] and AFL dehydrogenase (AFB1 production) in four commercial poultry species (chicken, quail, turkey and duck). Large differences were found in AFB1 reductase activity, being the chicken the most efficient producer of AFL (highest CLint value). Oxidation of AFL to AFB1 showed only slight differences among the different poultry species. On average all species produced AFB1 from AFL at a similar rate, except for the turkey which produced AFB1 from AFL at a significantly lower rate than chickens and quail, but not ducks. Although the turkey and duck showed differences in AFL oxidation Vmax and KM parameters, their CLint values did not differ significantly. The ratio AFB1 reductase/AFL dehydrogenase enzyme activity was inversely related to the known in vivo sensitivity to AFB1 being highest for the chicken, lowest for the duck and intermediate for turkeys and quail. Since there is no evidence that AFL is a toxic metabolite of AFB1, these results suggest that AFL production is a detoxication reaction in poultry. Conversion of AFB1 to AFL prevents the formation of the AFB1-8,9-exo-epoxide which, upon conversion to AFB1-dihydrodiol, is considered to be the metabolite responsible for the acute toxic effects of AFB1.

Investigation of the transport of aflatoxin M1 by the transporter ABCG2 in bovine mammary epithelial cells

Aflatoxin M1 (AFM1), a hydrogenated metabolite of aflatoxin B1 (AFB1), is one of the most common and threatening aflatoxins found in milk and dairy products. The ATP-binding cassette G2 efflux transporter (ABCG2) plays an important role in the mammary transport of drugs and toxins in animals, but whether ABCG2 could affect the transport of AFM1 in bovine mammary epithelial cells (BMECs) has not been clarified. Therefore, this study aimed to investigate the effects of AFM1 on tight junctions (TJs), lactation and cells proliferation in BMECs, and explored the regulatory role of ABCG2 in AFM1 transport in vitro in BMECs. The results showed that the integrity of the TJs of BMECs was not permanently compromised after exposure to AFM1. AFM1 exposure had no obvious effects on lactation or cell proliferation in BMECs. Gene function study revealed that ABCG2 was a positive regulator of AFM1 transport. These results demonstrate that it has little effect on TJs, lactation or cell proliferation in BMECs exposed to a small dose of AFM1, and ABCG2 is a critical regulator for AFM1 transport in BMECs.

Aflatoxin Exposure from Milk in Rural Kenya and the Contribution to the Risk of Liver Cancer

Milk is an important commodity in Kenya; the country has the largest dairy herd and highest per capita milk consumption in East Africa. As such, hazards in milk are of concern. Aflatoxin M1 (AFM1) is a toxic metabolite of aflatoxin B1 (AFB1) excreted in milk by lactating animals after ingesting AFB1-contaminated feeds. This metabolite is injurious to human health, but there is little information on the risk to human health posed by AFM1 in milk in rural Kenya. To fill this gap, a quantitative risk assessment (QRA) applying probabilistic statistical tools to quantify risks was conducted. This assessed the risk of liver cancer posed by AFM1 in milk, assuming 10-fold lower carcinogenicity than AFB1. Data from four agro–ecological zones in Kenya (semi-arid, temperate, sub-humid and humid) were used. We estimated that people were exposed to between 0.3 and 1 ng AFM1 per kg body weight per day through the consumption of milk. The annual incidence rates of cancer attributed to the consumption of AFM1 in milk were 3.5 × 10−3 (95% CI: 3 × 10−3–3.9 × 10−3), 2.9 × 10−3 (95% CI: 2.5 × 10−3–3.3 × 10−3), 1.4 × 10−3 (95% CI: 1.2 × 10−3–1.5 × 10−3) and 2.7 × 10−3 (95% CI: 2.3 × 10−3–3 × 10−3) cancers per 100,000 in adult females, adult males, children 6–18 years old, and in children less than five years old, respectively. Our results show that aflatoxin exposure from milk contributes relatively little to the incidence of liver cancer. Nonetheless, risk managers should take action based on cumulative exposure from all sources of aflatoxins.

Aflatoxin M1 in UHT cow milk samples collected in Burdur, Turkey

Aflatoxins are secondary metabolites of toxigenic moulds of the Aspergillus species. Aflatoxin M1, a metabolite of the potent carcinogen aflatoxin B1 (AFB1) occurs in milks of animals consuming feed contaminated with AFB1. The aim of this study was to investigate the occurrence and levels of aflatoxin M1 (AFM1) in UHT milk samples consumed in Burdur city markets. In 2018, a total of 78 UHT milk samples were randomly collected from different markets of Burdur. The occurrence and contamination levels of AFM1 in the samples were investigated by the competitive enzyme-linked immunosorbent assay (ELISA) method. Aflatoxin M1 was detected in 24 of 78 samples (30.77 %) in concentrations between 4.30-127.44 ng/L (mean level: 47.54 ng/L). AFM1 levels in 11 of these 24 positive samples were above legal limits of Turkey which is 50 ng/L for milk samples. It is concluded that the occurrence of AFM1 in milk samples in particular may be considered as a possible hazard for public health.

Micronuclei Formation by Promutagens in Metabolism-Incompetent V79 Cells Interacting With Activation-Proficient Cells in Various Experimental Settings.

The accessibility of reactive metabolites to test cells is critical for a genotoxic response. However, sulfo-conjugates formed outside may not readily enter cells, and some metabolites formed by cytochromes P450 (CYPs) may not endure transport. This topic was addressed in the present study, using V79 cells engineered for human CYPs and/or a sulfotransferase (SULT). First, 1-methylpyrene, 1-hydroxymethylpyrene, benzo[a]pyrene, and aflatoxin B1 significantly induced micronuclei in V79-hCYP1A2-hSULT1A1, V79-hSULT1A1, V79-hCYP1A1, and V79-hCYP1A2 cells, respectively. Subsequently, we used these cell lines as external activating systems in various experimental settings in combination with V79-derived target cells lacking critical enzymes. 1-Methylpyrene (activated by CYPs and SULTs sequentially) showed an activity similar to that in V79-hCYP1A2-hSULT1A1 cells, in each following model: a mixed V79-hCYP1A2:V79-hSULT1A1 (1:1) culture, exposure of V79-hCYP1A2 to 1-methylpyrene followed by transfer of medium to V79-hSULT1A1 target cells, and V79-hSULT1A1 communicating with V79-hCYP1A2 through 0.4-μm pores and over a 1-mm distance in a unique transwell system. These results suggest ready transfer of 1-hydroxymethylpyrene formed in V79-hCYP1A2 to V79-hSULT1A1 for further activation. In the last two models, with V79-hSULT1A1 for activation and V79-Mz as target, 1-hydroxymethylpyrene induced micronuclei mildly, suggesting limited intercellular transfer of the ultimate genotoxicant, 1-sulfooxymethylpyrene. Benzo[a]pyrene induced micronuclei in V79-Mz communicating with V79-hCYP1A1 via porous membranes, whereas aflatoxin B1 was inactive in V79-Mz communicating with V79-hCYP1A2. Our results suggest that the sulfo-conjugate tested may have difficulty entering cells for a genotoxic effect, and the reactive metabolite of aflatoxin B1, unlike that of benzo[a]pyrene, could not travel an adequate distance to enter cells. Environ. Mol. Mutagen. 61:224-234, 2020. © 2019 Wiley Periodicals, Inc.