Combined toxic exposures and human health: biomarkers of exposure and effect

Impact of gestational bisphenol A on oxidative stress and free fatty acids: Human association and interspecies animal testing studies

Bisphenol A (BPA) is a high production volume chemical and an endocrine disruptor. Developmental exposures to BPA have been linked to adult metabolic pathologies, but the pathways through which these disruptions occur remain unknown. This is a comprehensive interspecies association vs causal study to evaluate risks posed by prenatal BPA exposure and to facilitate discovery of biomarkers of relevance to BPA toxicity. Samples from human pregnancies during the first trimester and at term, as well as fetal and/or adult samples from prenatally BPA-treated sheep, rats, and mice, were collected to assess the impact of BPA on free fatty acid and oxidative stress dynamics. Mothers exposed to higher BPA during early to midpregnancy and their matching term cord samples displayed increased 3-nitrotyrosine (NY), a marker of nitrosative stress. Maternal samples had increased palmitic acid, which was positively correlated with NY. Sheep fetuses and adult sheep and rats prenatally exposed to a human-relevant exposure dose of BPA showed increased systemic nitrosative stress. The strongest effect of BPA on circulating free fatty acids was observed in adult mice in the absence of increased oxidative stress. This is the first multispecies study that combines human association and animal causal studies assessing the risk posed by prenatal BPA exposure to metabolic health. This study provides evidence of the induction of nitrosative stress by prenatal BPA in both the mother and fetus at time of birth and is thus supportive of the use of maternal NY as a biomarker for offspring health.

Effects of a mixture of volatile organic compounds on total DNA and gene expression of heat shock proteins in Drosophila melanogaster

The genotoxic effects of a mixture of 13 volatile organic compounds (VOCs) on total DNA profiles and the expression of heat shock proteins (HSPs) HSP26, HSP60, HSP70, and HSP83 in fruit fly tissues were examined. Drosophila melanogaster Oregon R(+), reared under controlled conditions on artificial diets, was treated with 13 VOCs commonly found in water at concentrations of 10, 20, 50, and 75 ppb for 1 and 5 days. Band changes were clearly detected in random amplified polymorphic DNA assay, especially at the 50- and 75-ppb exposure levels, for both treatment periods. In addition, there were clear differences in the band profiles of the treated and untreated flies with changes in the band intensity and the loss/appearance of bands. Although the genomic template stability (GTS) exhibited irregular changes at the first day, significant decreases in GTS were observed after 5 days of VOC application. The lowest GTS value (27.77 ± 1.96 %) was detected at the 75-ppb level after 5 days of the treatment. Quantitative real-time polymerase chain reaction analysis showed a significant increase in the relative expression of HSP26 and HSP60 after 1 and 5 days of the treatment, respectively. The expression of HSP70 increased significantly at all treatment concentrations and times. However, the greatest increase in expression level of HSP70 (4.2-fold) occurred at 20 ppb after 5 days of the treatment. HSP83 was the least affected by exposure to the VOCs. We conclude that trace levels of a mixture of VOCs can exert genotoxic effects on both total DNA and HSP levels in Drosophila.

Analysis of pollutant-induced changes in mitochondrial DNA methylation

There is increasing evidence that exposure to air pollutants is associated with human disease and may act through epigenetic modification of the nuclear genome, but there have been few publications describing their impact upon the mitochondrial genome. Mitochondrial DNA may be more susceptible to pollutant-induced changes via increased oxidative stress in the cell, and therefore this field of research is of growing interest. Many techniques employed to study DNA methylation of the nuclear genome are also applicable to mitochondrial epigenetic studies. In this chapter, we describe a protocol for the isolation of mitochondrial DNA from peripheral blood samples and the analysis of 5-methylcytosine content by bisulfite pyrosequencing.

Effects of subchronic exposure to cadmium and diazinon on testis and epididymis in rats

The present study aimed to elucidate the structural changes in testis and epididymis of adult rats following subchronic peroral administration of cadmium at 30 mg/L, diazinon at 40 mg/L, cadmium at 30 mg/L, and diazinon at 40 mg/L, respectively. At the end of 90-day experiment, the samples of the testes and epididymis were assayed by qualitative and quantitative histological methods. The testis and epididymis weights increased following exposure to cadmium and simultaneous exposure to cadmium and diazinon. Testicular damage following cadmium and diazinon coexposure was significantly less expressive than in groups with individual administration of these compounds. Cadmium caused a significant thickening of seminiferous epithelium, cellular degeneration, and necrosis. Desquamation of immature germ cells resulted in a significant increase of intraepithelial spaces and reduced tubule volume in all experimental groups. Vascular dilation and congestion were detected in the interstitial tissue. The changes in epididymal histology in the group exposed to cadmium and group exposed simultaneously included a reduction of epithelium, necrotic epithelial cells, vasoconstriction, and interstitial edema together with mononuclear cell infiltration. Results did not indicate a synergistic or any additional effect from the simultaneous administration of both toxicants. Further research is needed to determine the significance and the mechanism of the adverse effects.

Prepubertal exposure to genistein alleviates di-(2-ethylhexyl) phthalate induced testicular oxidative stress in adult rats

Di-(2-ethylhexyl) phthalate (DEHP) is the most widely used plastizer in the world and can suppress testosterone production via activation of oxidative stress. Genistein (GEN) is one of the isoflavones ingredients exhibiting weak estrogenic and potentially antioxidative effects. However, study on reproductive effects following prepubertal multiple endocrine disrupters exposure has been lacking. In this study, DEHP and GEN were administrated to prepubertal male Sprague-Dawley rats by gavage from postnatal day 22 (PND22) to PND35 with vehicle control, GEN at 50 mg/kg body weight (bw)/day (G), DEHP at 50, 150, 450 mg/kg bw/day (D50, D150, D450) and their mixture (G + D50, G + D150, G + D450). On PND90, general morphometry (body weight, AGD, organ weight, and organ coefficient), testicular redox state, and testicular histology were studied. Our results indicated that DEHP could significantly decrease sex organs weight, organ coefficient, and testicular antioxidative ability, which largely depended on the dose of DEHP. However, coadministration of GEN could partially alleviate DEHP-induced reproductive injuries via enhancement of testicular antioxidative enzymes activities, which indicates that GEN has protective effects on DEHP-induced male reproductive system damage after prepubertal exposure and GEN may have promising future in its curative antioxidative role for reproductive disorders caused by other environmental endocrine disruptors.

Metabonomic analysis of serum of workers occupationally exposed to arsenic, cadmium and lead for biomarker research: a preliminary study

Environmental metabonomics is the application of metabonomics to characterize the interactions of organisms with their environment. Metabolic profiling is an exciting addition to the armory of the epidemiologist for the discovery of new disease risk biomarkers and diagnostics. This work is a continuation of research searching for preclinical serum markers in a group of 389 healthy smelter workers exposed to lead, cadmium and arsenic. Changes in the metabolic profiles were studied using Proton Nuclear Magnetic Resonance Spectroscopy on pooled serum samples from both the metal exposed and control groups. These multivariate metabonomic datasets were analyzed with Principal Component Analysis and Partial Least Squares Discriminant Analysis. Analysis of metabolic profiles of people exposed to heavy metals suggests energy metabolism disturbance induced by heavy metals. Changes in lipid fraction (very-low-density lipoprotein - VLDL, low-density lipoprotein - LDL), unsaturated lipids and in the level of amino acids suggest perturbation of the metabolism of lipids and amino acids. This study illustrated the high reliability of NMR-based metabonomic profiling on the study of the biochemical effects induced by the mixture of heavy metals. This approach is capable of identifying intermediate biomarkers of response to toxicants at environmental/occupational concentrations, paving the way to its use in a monitoring of smelter workers exposed to low doses of lead, cadmium and arsenic.

Genotoxicity in earthworm after combined treatment of ionising radiation and mercury

This study was performed to investigate the acute genotoxic effects of mercury and radiation on earthworms (Eisenia fetida). The levels of DNA damage and the repair kinetics in the coelomocytes of E. fetida treated with mercuric chloride (HgCl₂) and ionising radiation (gamma rays) were analysed by means of the comet assay. For detection of DNA damage and repair, E. fetida was exposed to HgCl₂ (0-160 mg kg(-1)) and irradiated with gamma rays (0-50 Gy) in vivo. The increase in DNA damage depended on the concentration of mercury or dose of radiation. The results showed that the more the oxidative stress induced by mercury and radiation the longer the repair time that was required. When a combination of HgCl₂ and gamma rays was applied, the cell damage was much higher than those treated with HgCl₂ or radiation alone, which indicated that the genotoxic effects were increased after the combined treatment of mercury and radiation.

Does area deprivation modify the association between exposure to a nitrate and low-dose atrazine metabolite mixture in drinking water and small for gestational age? A historic cohort study

Birth weight may be influenced by environmental and socio-economic factors that could interact. The main objective of our research was to investigate whether area deprivation may modify the association between drinking water exposure to a mixture of atrazine metabolites and nitrates during the second trimester of pregnancy and prevalence of small for gestational age (SGA) neonates. We conducted a historic cohort study in Deux-Sèvres, France between 2005 and 2010, using birth records, population census and regularly performed drinking water withdrawals at community water systems. Exposure to an atrazine metabolite/nitrate mixture in drinking water was divided into six classes according to the presence or absence of atrazine metabolites and to the terciles of nitrate concentrations in each trimester of pregnancy. We used a logistic regression to model the association between SGA and mixture exposure at the second trimester while taking into account the area deprivation measured by the Townsend index as an effect modifier and controlling for the usual confounders. We included 10,784 woman-neonate couples. The risk of SGA when exposed to second tercile of nitrate without atrazine metabolites was significantly greater in women living in less deprived areas (OR = 2.99; 95 % CI (1.14, 7.89)), whereas it was not significant in moderately and more deprived areas. One of the arguments used to explain this result is the presence of competing risk factors in poorer districts.

Do GSTT1 and GSTM1 polymorphisms influence intoxication events in individuals occupationally exposed to pesticides?

This study evaluated the variability of GSTM1 and GSTT1 polymorphisms in individuals occupationally exposed to pesticides in ten Goias municipalities that present intense agricultural activity. We evaluated blood samples of 235 individuals, which 120 were rural workers occupationally exposed to pesticides and 115 formed the control group, analyzing GST polymorphisms by quantitative polymerase chain reaction (qPCR).The exposed group consisted of 111 men and nine women only getting an average of 39 ± 9 years. These workers were from ten rural municipalities situated at Goias state. It was found that 18 % of the exposed individuals had the GSTT1 null genotype and 49 % had the GSTM1 null genotype, and 10 % had both null genotypes. Data as intoxication (42 %), use of Personal Protection Equipment (PPE; 52 %) and if the worker prepared the pesticide (7 %), or if just applied the pesticide (22 %) or if the worker prepared and applied (71 %) have all been correlated with genetic polymorphisms. There were no statistically significant differences between the GSTM1 and GSTT1 polymorphisms between control and exposed groups. Finally, we could not associate a null GSTT1 or null GSTM1 polymorphisms or both to intoxication events caused by pesticides, but instead we presented the importance to use PPE to prevent such harm, once we found a statistically significant association between the use of PPE and events of intoxication (p ≤ 0.001).

Drinking-water exposure to a mixture of nitrate and low-dose atrazine metabolites and small-for-gestational age (SGA) babies: a historic cohort study

BACKGROUND

Groundwater, surface water and drinking water are contaminated by nitrates and atrazine, an herbicide. They are present as a mixture in drinking water and with their endocrine-disrupting activity, they may alter fetal growth.

OBJECTIVES

To study an association between drinking-water atrazine metabolites/nitrate mixture exposure and small-for-gestational-age(SGA).

METHODS

A historic cohort study based on birth records and drinking-water nitrate and pesticide measurements in Deux-Sèvres (France) between 2005 and 2009 was carried out. Exposure to drinking-water atrazine metabolites/nitrate mixture was divided into 6 classes according to the presence or absence of atrazine metabolites and to terciles of nitrate concentrations in each trimester of pregnancy. Regression analysis of SGA by mixture exposure at second trimester was subsequently conducted.

RESULTS

We included 11,446 woman-neonate couples of whom 37.0% were exposed to pesticides, while 99.9% of the women were exposed to nitrates. Average nitrate concentration was from 0 to 63.30 mg/L. In the second trimester of pregnancy, the risk of SGA was different with mixture exposure when drinking-water atrazine metabolites, mainly 2 hydroxyatrazine and desethylatrazine, were present and nitrate dose exposure increased: compared to single first tercile of nitrate concentration exposure, single second tercile exposure OR was 1.74 CI 95% [1.10; 2.75] and atrazine metabolites presence in the third tercile of nitrate concentration exposure OR was 0.87 CI 95% [0.45;1.67].

CONCLUSIONS

It is possible that the association found at the second trimester of exposure with regard to birth weight may likewise be observed before birth, with regard to the estimated fetal weight, and that it might change in the event that the atrazine metabolites dose were higher or the nitrate dose lower. It would appear necessary to further explore the variability of effects.

Obesity and metabolic comorbidities: environmental diseases?

Obesity and metabolic comorbidities represent increasing health problems. Endocrine disrupting compounds (EDCs) are exogenous agents that change endocrine function and cause adverse health effects. Most EDCs are synthetic chemicals; some are natural food components as phytoestrogens. People are exposed to complex mixtures of chemicals throughout their lives. EDCs impact hormone-dependent metabolic systems and brain function. Laboratory and human studies provide compelling evidence that human chemical contamination can play a role in obesity epidemic. Chemical exposures may increase the risk of obesity by altering the differentiation of adipocytes. EDCs can alter methylation patterns and normal epigenetic programming in cells. Oxidative stress may be induced by many of these chemicals, and accumulating evidence indicates that it plays important roles in the etiology of chronic diseases. The individual sensitivity to chemicals is variable, depending on environment and ability to metabolize hazardous chemicals. A number of genes, especially those representing antioxidant and detoxification pathways, have potential application as biomarkers of risk assessment. The potential health effects of combined exposures make the risk assessment process more complex compared to the assessment of single chemicals. Techniques and methods need to be further developed to fill data gaps and increase the knowledge on harmful exposure combinations.

Modeling autism: a systems biology approach

Autism is the fastest growing developmental disorder in the world today. The prevalence of autism in the US has risen from 1 in 2500 in 1970 to 1 in 88 children today. People with autism present with repetitive movements and with social and communication impairments. These impairments can range from mild to profound. The estimated total lifetime societal cost of caring for one individual with autism is $3.2 million US dollars. With the rapid growth in this disorder and the great expense of caring for those with autism, it is imperative for both individuals and society that techniques be developed to model and understand autism. There is increasing evidence that those individuals diagnosed with autism present with highly diverse set of abnormalities affecting multiple systems of the body. To this date, little to no work has been done using a whole body systems biology approach to model the characteristics of this disorder. Identification and modelling of these systems might lead to new and improved treatment protocols, better diagnosis and treatment of the affected systems, which might lead to improved quality of life by themselves, and, in addition, might also help the core symptoms of autism due to the potential interconnections between the brain and nervous system with all these other systems being modeled. This paper first reviews research which shows that autism impacts many systems in the body, including the metabolic, mitochondrial, immunological, gastrointestinal and the neurological. These systems interact in complex and highly interdependent ways. Many of these disturbances have effects in most of the systems of the body. In particular, clinical evidence exists for increased oxidative stress, inflammation, and immune and mitochondrial dysfunction which can affect almost every cell in the body. Three promising research areas are discussed, hierarchical, subgroup analysis and modeling over time. This paper reviews some of the systems disturbed in autism and suggests several systems biology research areas. Autism poses a rich test bed for systems biology modeling techniques.

The combined effect of persistent organic pollutants in the serum POP mixture in Greenlandic Inuit: xenoestrogenic, xenoandrogenic and dioxin-like transactivities

Greenlandic Inuit have high body burden of persistent organic pollutants (POPs). We analyzed the combined effect of the actual lipophilic serum POP mixture on estrogen-, androgen- and aryl hydrocarbon-receptor functions as effect biomarkers, and the associations between the effect biomarkers and serum POPs, and lifestyle characteristics. The serum POPs were extracted from 232 Inuit from Ittoqqortoormiit, Narsaq and Qeqertarsuaq. The POP-related receptor transactivities correlated negatively to the POP levels and were associated to the lifestyle characteristics. The POP-related receptor transactivities can be used as effect biomarkers. The serum POPs have hormone disruptive potentials.

Toxic effects of pesticide mixtures at a molecular level: their relevance to human health

Pesticides almost always occur in mixtures with other ones. The toxicological effects of low-dose pesticide mixtures on the human health are largely unknown, although there are growing concerns about their safety. The combined toxicological effects of two or more components of a pesticide mixture can take one of three forms: independent, dose addition or interaction. Not all mixtures of pesticides with similar chemical structures produce additive effects; thus, if they act on multiple sites their mixtures may produce different toxic effects. The additive approach also fails when evaluating mixtures that involve a secondary chemical that changes the toxicokinetics of the pesticide as a result of its increased activation or decreased detoxification, which is followed by an enhanced or reduced toxicity, respectively. This review addresses a number of toxicological interactions of pesticide mixtures at a molecular level. Examples of such interactions include the postulated mechanisms for the potentiation of pyrethroid, carbaryl and triazine herbicides toxicity by organophosphates; how the toxicity of some organophosphates can be potentiated by other organophosphates or by previous exposure to organochlorines; the synergism between pyrethroid and carbamate compounds and the antagonism between triazine herbicides and prochloraz. Particular interactions are also addressed, such as those of pesticides acting as endocrine disruptors, the cumulative toxicity of organophosphates and organochlorines resulting in estrogenic effects and the promotion of organophosphate-induced delayed polyneuropathy.

Bioaccumulative and conchological assessment of heavy metal transfer in a soil-plant-snail food chain

BACKGROUND

Copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) can pose serious threats to environmental health because they tend to bioaccumulate in terrestrial ecosystems. We investigated under field conditions the transfer of these heavy metals in a soil-plant-snail food chain in Banat area, Romania. The main goal of this paper was to assess the Roman snail (Helix pomatia) usefulness in environmental monitoring as bioindicator of heavy metal accumulation. Eight sampling sites, selected by different history of heavy metal (HM) exposure, were chosen to be sampled for soil, nettle leaves, and newly matured snails. This study also aimed to identify the putative effects of HM accumulation in the environment on phenotypic variability in selected shell features, which included shell height (SH), relative shell height (RSH), and whorl number (WN).

RESULTS

Significantly higher amounts of HMs were accumulated in snail hepatopancreas and not in foot. Cu, Zn, and Cd have biomagnified in the snail body, particularly in the hepatopancreas. In contrast, Pb decreased when going up into the food chain. Zn, Cd, and Pb correlated highly with each other at all levels of the investigated food chain. Zn and Pb exhibited an effective soil-plant transfer, whereas in the snail body only foot Cu concentration was correlated with that in soil. There were significant differences among sampling sites for WN, SH, and RSH when compared with reference snails. WN was strongly correlated with Cd and Pb concentrations in nettle leaves but not with Cu and Zn. SH was independent of HM concentrations in soil, snail hepatopancreas, and foot. However, SH correlated negatively with nettle leaves concentrations for each HM except Cu. In contrast, RSH correlated significantly only with Pb concentration in hepatopancreas.

CONCLUSIONS

The snail hepatopancreas accumulates high amounts of HMs, and therefore, this organ can function as a reliable biomarker for tracking HM bioavailability in soil. Long-term exposure to HMs via contaminated food might influence the variability of shell traits in snail populations. Therefore, our results highlight the Roman snail (Helix pomatia) potential to be used in environmental monitoring studies as bioindicator of HM pollution.

Can persistent organic pollutants and plastic-associated chemicals cause cardiovascular disease?

During the last decade, associations between persistent organic pollutants (POPs), such as polychlorinated biphenyls, dioxins and pesticides, and cardiovascular (CV) risk factors and overt CV disease (CVD) have been reported in humans. Recently, associations between plastic-associated chemicals (PACs), such as bisphenol A and phthalates, and CVD have also begun to emerge. Several approaches to evaluating such associations have been used: accidents with a high level of exposure, occupational exposure studies, geographical studies of subjects living near a contaminated area and traditional case-control or cohort studies with measurements of circulating levels of different environmental contaminants in the general population. Exposure to POPs has consistently been associated with diabetes using all the approaches described above, including prospective studies. The evidence regarding associations between exposure to POPs and other CV risk factors, such as hypertension, obesity and lipids, is less strong and is mainly based on cross-sectional data. Associations between overt CVD and POPs have been reported using all the above approaches, but prospective data from population-based studies are still lacking to provide firm evidence of an important and independent role of POP exposure in the pathogenesis of CVD. Nevertheless, taken together, current evidence suggests that further longitudinal and experimental studies should be conducted to investigate the effect of exposure to both POPs and PACs, such as bisphenol A and phthalates.

Hormones and endocrine-disrupting chemicals: low-dose effects and nonmonotonic dose responses

For decades, studies of endocrine-disrupting chemicals (EDCs) have challenged traditional concepts in toxicology, in particular the dogma of "the dose makes the poison," because EDCs can have effects at low doses that are not predicted by effects at higher doses. Here, we review two major concepts in EDC studies: low dose and nonmonotonicity. Low-dose effects were defined by the National Toxicology Program as those that occur in the range of human exposures or effects observed at doses below those used for traditional toxicological studies. We review the mechanistic data for low-dose effects and use a weight-of-evidence approach to analyze five examples from the EDC literature. Additionally, we explore nonmonotonic dose-response curves, defined as a nonlinear relationship between dose and effect where the slope of the curve changes sign somewhere within the range of doses examined. We provide a detailed discussion of the mechanisms responsible for generating these phenomena, plus hundreds of examples from the cell culture, animal, and epidemiology literature. We illustrate that nonmonotonic responses and low-dose effects are remarkably common in studies of natural hormones and EDCs. Whether low doses of EDCs influence certain human disorders is no longer conjecture, because epidemiological studies show that environmental exposures to EDCs are associated with human diseases and disabilities. We conclude that when nonmonotonic dose-response curves occur, the effects of low doses cannot be predicted by the effects observed at high doses. Thus, fundamental changes in chemical testing and safety determination are needed to protect human health.

A reliable method by ultra-performance liquid chromatography coupled with tandem mass spectrometry to quantify and confirm simultaneously the presence of solvent metabolites in workers' urine

Ultra-performance liquid chromatography coupled with tandem mass spectrometry was used for the biological monitoring of workers occupationally exposed to solvents. The method was developed using a triple quadrupole to investigate the relevant urinary metabolites of styrene, namely mandelic acid and phenylglyoxylic acid. The method provides quantitative and qualitative data to give additional assurance about the nature of the contaminant analyzed in workers' urine. A full scan and a product ion scan were acquired within the chromatographic peak acquired in MRM. For the two metabolites, the repeatability was 96%, the precision ≥97%, and the accuracy ≥93 ± 3%. The quantitative performances were not influenced by the inclusion of simultaneous full scan acquisition as compared to a usual quantitative approach. Footprints of each substance of interest were obtained at each injection, and full scan data can be interrogated for the presence of interferences and other contaminants. The method developed has been submitted to random real samples from both non-occupationally and occupationally exposed workers. The urines of non-occupationally exposed workers were all free of mandelic acid, phenylglyoxylic acid and putative interferences showing the high selectivity of the method. However, the urines of occupationally exposed workers were robustly quantified. The levels of mandelic acid and phenylglyoxylic acid ranged between 0.2 and 9 mM, and the footprints of each metabolite and structural information were acquired in parallel with the quantitative results, thus providing unquestionable data about the nature of the contaminant and the levels reported. The combination of qualitative information acquired simultaneously with quantitative results provides the structural information needed in case of questions, without any harmful effect on the robustness and throughput of the quantitative analysis.

Genetic Programming as a tool for identification of analyte-specificity from complex response patterns using a non-specific whole-cell biosensor

Whole-cell biosensors are mostly non-specific with respect to their detection capabilities for toxicants, and therefore offering an interesting perspective in environmental monitoring. However, to fully employ this feature, a robust classification method needs to be implemented into these sensor systems to allow further identification of detected substances. Substance-specific information can be extracted from signals derived from biosensors harbouring one or multiple biological components. Here, a major task is the identification of substance-specific information among considerable amounts of biosensor data. For this purpose, several approaches make use of statistical methods or machine learning algorithms. Genetic Programming (GP), a heuristic machine learning technique offers several advantages compared to other machine learning approaches and consequently may be a promising tool for biosensor data classification. In the present study, we have evaluated the use of GP for the classification of herbicides and herbicide classes (chemical classes) by analysis of substance-specific patterns derived from a whole-cell multi-species biosensor. We re-analysed data from a previously described array-based biosensor system employing diverse microalgae (Podola and Melkonian, 2005), aiming on the identification of five individual herbicides as well as two herbicide classes. GP analyses were performed using the commercially available GP software 'Discipulus', resulting in classifiers (computer programs) for the binary classification of each individual herbicide or herbicide class. GP-generated classifiers both for individual herbicides and herbicide classes were able to perform a statistically significant identification of herbicides or herbicide classes, respectively. The majority of classifiers were able to perform correct classifications (sensitivity) of about 80-95% of test data sets, whereas the false positive rate (specificity) was lower than 20% for most classifiers. Results suggest that a higher number of data sets may lead to a better classification performance. In the present paper, GP-based classification was combined with a biosensor for the first time. Our results demonstrate GP was able to identify substance-specific information within complex biosensor response patterns and furthermore use this information for successful toxicant classification in unknown samples. This suggests further research to assess perspectives and limitations of this approach in the field of biosensors.