Cumulative effects of phthalates harm Leydig cells during fetal development

More bad news for sperm…

2018 Study Highlights

  • Phthalates dose-dependently cause fetal Leydig cell aggregation.
  • DEHP is more potent to inhibit testosterone production than DEP.
  • DEP and DEHP can elicit dose addition effect on FLC development


Phthalate diesters, including di-(2-ethylhexyl) phthalate (DEHP) and diethyl phthalate (DEP), are chemicals to which humans are ubiquitously exposed. Humans are exposed simultaneously to multiple environmental chemicals, including DEHP and DEP. There is little information available about how each chemical may interact to each other if they were exposed at same time. The present study investigated effects of the combinational exposure of rats to DEP and DEHP on fetal Leydig cell development. The results showed that the gestational (GD12-20) exposure of DEP + DEHP resulted in synergistic and/or dose-additive effects on the development of fetal Leydig cell. The lowest observed adverse-effect levels (LOAEL) for fetal Leydig cell (aggregation and cell size), and StAR expressions were of 10 mg/kg and, lower than when these chemicals were exposed alone. Also, mathematical modeling the response curves supports the dose-addition model over integrated-addition model. Overall, these data demonstrate that individual phthalate with a similar mechanism of action can elicit cumulative, dose additive, and sometimes synergistic, effects on the development of male reproductive system when administered as a mixture.

  • In utero combined di-(2-ethylhexyl) phthalate and diethyl phthalate exposure cumulatively impairs rat fetal Leydig cell development, Science Direct, Volume 395, Pages 23–33, 15 February 2018.
  • Very high magnification micrograph of Leydig cells feature image wiki.

Banned pesticides continue to affect toxicity in streams

Sources, occurrence and predicted aquatic impact of legacy and contemporary pesticides in streams

Many toxic pesticides have been banned by the EU, however some can remain in the environment for many decades. Aquatic invertebrates are particularly vulnerable to pesticides, which can alter their feeding behaviour, growth and mobility. New research has found that persistent pesticides can increase toxicity in streams by up to 10 000 times compared to the residues of currently used pesticides. The researchers recommend these be taken into account when calculating overall toxicity.

Study Highlights

  • Findings comprised a range of contemporary and banned legacy pesticides in streams.
  • Groundwater is a significant pathway for some herbicides entering streams.
  • Legacy pesticides increased predicted aquatic toxicity by four orders of magnitude.
  • Sediment-bound insecticides were identified as the primary source for ecotoxicity.
  • Stream monitoring programs should include legacy pesticides to assess impacts.


Banned pesticides continue to affect toxicity in streams, Science for Environment Policy, 12 January 2017.

Sources, occurrence and predicted aquatic impact of legacy and contemporary pesticides in streams, science direct, February 2015.

We couple current findings of pesticides in surface and groundwater to the history of pesticide usage, focusing on the potential contribution of legacy pesticides to the predicted ecotoxicological impact on benthic macroinvertebrates in headwater streams. Results suggest that groundwater, in addition to precipitation and surface runoff, is an important source of pesticides (particularly legacy herbicides) entering surface water. In addition to current-use active ingredients, legacy pesticides, metabolites and impurities are important for explaining the estimated total toxicity attributable to pesticides. Sediment-bound insecticides were identified as the primary source for predicted ecotoxicity. Our results support recent studies indicating that highly sorbing chemicals contribute and even drive impacts on aquatic ecosystems. They further indicate that groundwater contaminated by legacy and contemporary pesticides may impact adjoining streams. Stream observations of soluble and sediment-bound pesticides are valuable for understanding the long-term fate of pesticides in aquifers, and should be included in stream monitoring programs.

Assessment of the biodegradability of selected sulfa drugs in two polluted rivers in Poland

Effects of seasonal variations, accidental contamination, turbidity and salinity

Up to 90% of consumed drugs enter the environment. This may have negative effects on wildlife, especially when the drugs take long periods to break down. This study assessed the breakdown of sulphonamides — a class of antibacterials — in samples from two rivers in Poland. The results showed that sulphamethoxazole, a common veterinary antibiotic, was the most persistent and that various factors inhibit degradation, including low temperatures, heavy metal pollution and low pH.


  • Biodegradation rate of sulfonamides (SNs) in river water is variable.
  • Biodegradability of SNs depends on the growing season.
  • High concentration of salts in river water inhibits the SNs biodegradation.
  • Sulfamethoxazole could be classified as Persistent Organic Pollutant (POP).


Which factors make drugs persistent? A look at sulphonamides in Polish rivers, Science for Environment Policy, 12 January 2017.

Assessment of the biodegradability of selected sulfa drugs in two polluted rivers in Poland: Effects of seasonal variations, accidental contamination, turbidity and salinity, science direct, August 2016.

Image credit Janusz Nowak.

The aim of our study was to assess the aerobic biodegradation of four selected sulfonamides (sulfanilamide, sulfamethoxazole, sulfadiazine and sulfathiazole) using water samples drawn from highly polluted rivers. Additionally, we aimed to identify the factors that have a significant effect on the process efficiency.

The 19 water samples were collected from Brynica and Czarna Przemsza rivers (in Poland) at the same location at approximately monthly intervals. A characteristic feature of the results is the presence of significant differences between the rates of sulfonamides biodegradation in particular samples.

The sulfonamide most resistant to biodegradation was sulfamethoxazole, whereas sulfathiazole was most biodegradable. Seasonal variations and related microbial population changes had the most significant effects on sulfonamides biodegradation, e.g., the studied process was highly inhibited during wintertime. A decrease in the biodegradation rate in the river water could be caused by an accidental water pollution by industrial wastewater with heavy metals, an increase in salinity and a decrease in pH, and turbidity.

Herbicide found in German estuaries, transported to the Baltic Sea

Glyphosate and AMPA in the estuaries of the Baltic Sea method optimization and field study

Glyphosate is a widely used herbicide, able to kill a broad range of plants (‘weeds’) that compete with crops. This study used a validated method to assess its presence in 10 German estuaries that lead to the Baltic Sea. All but one was contaminated with glyphosate, and all were contaminated with its metabolite AMPA. The researchers recommend risk assessments for these chemicals in the Baltic Sea and other marine environments.


  • An LC–HESI-MS/MS method for glyphosate and AMPA analysis in estuarine water
  • Contamination of the Baltic estuaries with glyphosate and AMPA
    Glyphosate and AMPA concentrations exceed the European guideline of 100 ng/L.
  • The first study on transport glyphosate and AMPA from land to sea
  • Glyphosate concentrations may cause a toxic effect in some Baltic rivers and estuaries.


Herbicide found in German estuaries, transported to the Baltic Sea, Science for Environment Policy, 25 November 2016.

Glyphosate and AMPA in the estuaries of the Baltic Sea method optimization and field study, science direct, November 2015.

Muta @ the Baltic Sea by Satorare.

Water samples from ten German Baltic estuaries were collected in 2012 in order to study the presence of the herbicide glyphosate, its primary metabolite AMPA and their potential transport to the marine environment. For the analyses an LC–MS/MS based analytical method after derivatization with FMOC-Cl was optimized and validated for marine water samples. All investigated estuarine stations were contaminated with AMPA and nine of them also with glyphosate. Concentration ranges observed were 28 to 1690 ng/L and 45 to 4156 ng/L for glyphosate and AMPA, respectively with strong spatial and temporal fluctuations. Both contaminants were found at inbound sampling sites in the stream Muehlenfliess and concentrations decreased along the salinity gradient to the estuaries of the Baltic Sea. The data obtained in this study clearly depict the transport of glyphosate and AMPA to the Baltic Sea. Hence, detailed fate and risk assessment for both contaminants in marine environments are required.

Common veterinary antibiotics not quickly biodegradable infiltrate our aquatic environment

Which factors make drugs persistent? A look at sulphonamides in Polish rivers

Pharmaceutical pollution is a growing environmental concern in the EU, as the world’s second biggest consumer of human medicinal products. Up to 90% of orally administered drugs are excreted in the urine of animals and people1 , which means medicinal products can infiltrate the aquatic environment, where they may have negative effects on wildlife.

This study focused on sulphonamides, a group of chemicals used mainly as anti-bacterial agents. Although sulphonamides are now rarely used in human medicine, they remain important in animal medicine; in agriculture, up to 58 milligrams of sulphonamide can be used to produce just 1 kilogram of meat. As a result, levels of these drugs can reach 400 milligrams per kilogram in manure. The presence of these chemicals in the environment could promote drug resistance in bacteria in soil. After leaching into nearby water bodies, the drugs could also have negative impacts on aquatic organisms.

Which factors make drugs persistent? A look at sulphonamides in Polish rivers, Science for Environment Policy, 12 January 2017.

Assessment of the biodegradability of selected sulfa drugs in two polluted rivers in Poland: Effects of seasonal variations, accidental contamination, turbidity and salinity, science direct, August 2016.

Image credit PracticalCures.

Various factors are key to assessing the risk from a chemical, including its toxicological properties and how quickly it is broken down — the latter being the focus of this study. Chemicals that persist in the environment pose a risk because they can accumulate up the food chain, enabling them to reach potentially toxic levels. Some persistent chemicals can also move long distances, allowing them to travel far from their source.

According to the guidelines of the Stockholm Convention, substances with a half-life in the aquatic environment of over two months (i.e. it takes over two months for the chemical to break down to 50% of its original concentration) can be classified as persistent. Stockholm Convention parties, including the EU, are required to implement special procedures for such substances. Data suggest that the half-life of some sulphonamides is over two months, yet they are not considered persistent organic pollutants.

Many factors can affect the biodegradation rate of sulphonamides, such as the amount of light, the pH of the water and the presence of oxygen. This study investigated the biodegradability of four sulphonamides: sulphanilamide, sulpha-methoxazole, sulphadiazine and sulphathiazole. The researchers investigated the influence of weather conditions, water quality and experimental procedure on the breakdown of these sulphonamides in water samples collected from rivers in Poland.

A total of 19 water samples were collected from two highly polluted Polish rivers. Both rivers flow through one of the EU’s largest urban areas (the Upper Silesian Industrial Region), which has over 12 active coal mines and metallurgical industries and a human population of around 3 million. Immediately after sampling, a concentrated solution of sulphonamides was added to the water. The researchers quantified the concentration of the drugs in each sample over 28 days.

Before commencing biodegradation experiments, the researchers assessed the effect of sulphonamides on microorganisms in the water. After 18 hours of incubation, significant growth inhibition was observed, but after two days this inhibition decreased. This suggests that microorganisms are inhibited by the drugs but, over time, adapt to their presence.

Next, the researchers looked at how each drug was broken down by microbes (biodegraded). Microbial activity and thus biodegradation can depend on the effect of individual chemicals as well as external conditions such as temperature, leading to complex interactions.

Sulpha-methoxazole was the most resistant to biodegradation, with an average half-life of 72 days — meeting the definition of a persistent organic pollutant. As sulpha-methoxazole is the most commonly used sulphonamide in veterinary medicine and the most frequently detected in environmental samples, this result could be of environmental concern. Sulphathiazole was the most biodegradable, and had similar rates of biodegradation to the other two drugs, which were also rapidly broken down.

It is not only the type of sulphonamide that affects biodegradation. The researchers found that the factor with the biggest effect on biodegradation was temperature, with rates of breakdown significantly lower during the colder, winter season.

In Central European areas, vegetation increases with temperature from spring to autumn, leading to more biodiversity, higher microbial activity and a higher rate of biodegradation. However, during wintertime, temperatures drop and vegetation is suppressed, leading to reduced microbial activity and thus reduced biodegradation. This suggests the environmental risk associated with sulphonamides could be higher in the winter.

The authors also found a connection with pH, with acidity reducing degradation, and salt content (salinity), with higher salinity also reducing degradation (suggesting that removing salt from wastewater entering rivers could increase drug breakdown). Lower turbidity (the cloudiness of water, caused by particles it contains) also reduced breakdown, because the particles found in water support microorganisms. Finally, heavy-metal contamination from nearby industrial sites also inhibited sulphonamide degradation.

This study shows that various factors can reduce the biodegradation of sulphonamides and that risk may be particularly acute during winter, although further research is needed to clarify the ecological risk these compounds pose under different conditions

Legacy pesticides, and the compounds produced as they break down, remain a hazard to aquatic environments

Banned pesticides continue to affect toxicity in streams

The green revolution in the 1940s produced many effective and apparently safe pesticides, including synthetic insecticides such as DDT. Many of these chemicals were later discovered to have toxic effects, such as carcinogenicity, and subsequently banned from use. Another important issue is persistence; their long lifetimes mean some of these so-called ‘legacy’ pesticides can persist in the environment several decades after their use is prohibited.

Researchers examined the presence of both contemporary and legacy pesticides in 14 streams in Denmark, and used their results to predict the overall toxicity of the streams. They looked at both the influence of surface run-off and groundwater on concentrations in streams by taking samples in the streams shortly after periods of high precipitation, when surface runoff is high, and during a period of low precipitation, when groundwater was expected to be the largest source of inflow to the streams. Twelve of the streams were located in catchments where agriculture represents 80% or more of land use.

Banned pesticides continue to affect toxicity in streams, Science for Environment Policy, 12 January 2017.

Sources, occurrence and predicted aquatic impact of legacy and contemporary pesticides in streams, science direct, February 2015.

Water samples were collected from 2010 to 2012 mostly during May and June, the main periods when pesticides are applied to crops. The researchers used two methods to sample sediment: direct sampling of bed sediment using a core sampler, to give a snapshot for a specific moment in time; and time-integrated sampling for particulates (suspended sediment flowing in the stream), to which pesticides washed from agricultural fields can bind. They say this helped them to capture the pesticides which are expected to attach preferentially to (fine) particle surfaces.

The total toxicity was assumed to be the sum of the individual toxicities of all pesticides detected, neglecting any enhanced or reduced toxicity which may occur when different pesticides interact. The toxicity measure used was the LC50 — the concentration of the chemicals leading to 50% mortality for the test animals during an observation period of 48 hours — for the benchmark organism Daphnia magna. The study only provides an estimation of toxicity, by measuring the concentration of substances of known toxicity (the researchers did not assess the direct effect of the pesticides on aquatic organisms).

A total of 32 pesticides were detected. Two of the four most commonly detected were dinitro-ortho-cresol and trichloroacetic acid, both last sold in Denmark in the 1980s. The researchers believe these pesticides were generated in and transported from the atmosphere, rather than being present in surface runoff or groundwater. Three commonly detected pesticides in groundwater were mecoprop, dichlorprop, and dichlobenil. All of these chemicals were banned in Denmark in the late 1990s.

The estimated aquatic ecotoxicity increased by up to 10 000 times when legacy pesticides were included. Insecticides bound to sediments were found to be the largest source for the predicted ecotoxicity.

In this study, eight of the nine pesticides included on the Water Framework Directive’s1 list of 33 Priority Substances2 at the time of the study — shown to be of major concern for European Waters — were detected. For two of these, diuron and isoproturon, some detected concentrations were above or close to the EU aquatic Predicted No Effect Concentrations (PNECs)3 — below which no adverse ecosystem effects can be measured. Meanwhile the fungicide hexachlorobenzene — never authorised for use in Denmark — and the insecticide lindane were detected in the sediment at concentrations well above the sediment PNEC values used in the context of the selection of the 33 priority substances listed in Directive 2008/105/EC4 .

Since the study looked at only selected areas of Denmark, it is possible that similar results would not be found elsewhere. However, the researchers note that most of the maximum concentrations measured are similar to the reported median values of concentrations for European streams.

The study indicates that, alongside contemporary pesticides, legacy pesticides, and the compounds produced as they break down, remain a hazard to aquatic environments. The researchers recommend that monitoring programmes which estimate the ecotoxicity of streams be adjusted to reflect this. Furthermore, they advise that a greater research emphasis be put on the analysis of groundwater, often presumed to contain low levels of pollution. They also highlight that pesticides bound in particular to suspended sediments were a major source of predicted toxicity and need to be further studied.

Emerging, priority contaminants with endocrine active potentials in sediments, fish from the River Po, Italy

High levels of endocrine-disrupting chemicals found in sediments and fish from the Italian River Po and its Lambro tributary

Researchers have recommended that fish from some sections of the River Po and the River Lambro, one of the Italian River Po tributaries, should not be eaten due to high levels of some endocrine-disrupting chemicals in the river sediments and fish. This recommendation is based on an extensive update regarding pollution levels of such substances in the rivers.


There is a substantial lack of information on most priority pollutants, related contamination trends, and (eco)toxicological risks for the major Italian watercourse, the River Po. Targeting substances of various uses and origins, this study provides the first systematic data for the River Po on a wide set of priority and emerging chemicals, all characterized by endocrine-active potentials.

Flame retardants, natural and synthetic hormones, surfactants, personal care products, legacy pollutants, and other chemicals have been investigated in sediments from the River Po and its tributary, the River Lambro, as well as in four fish species from the final section of the main river. With few exceptions, all chemicals investigated could be tracked in the sediments of the main Italian river for tens or hundreds of kilometres downstream from the Lambro tributary.

Nevertheless, the results indicate that most of these contaminants, i.e., TBBPA, TCBPA, TBBPA-bis, DBDPE, HBCD, BPA, OP, TCS, TCC, AHTN, HHCB, and DDT, individually pose a negligible risk to the River Po. In contrast, PBDE, PCB, natural and synthetic estrogens, and to a much lower extent NP, were found at levels of concern either to aquatic life or human health. Adverse biological effects and prohibition of fish consumption deserve research attention and management initiatives, also considering the transport of contaminated sediments to transitional and coastal environments of the Italian river.

More Information
  • Emerging and priority contaminants with endocrine active potentials in sediments and fish from the River Po (Italy), US National Library of Medicine National Institutes of Health, Environmental science and pollution research international, NCBI PubMed PMID: 25956513, 2015 Sep.
  • High levels of endocrine-disrupting chemicals found in sediments and fish from the Italian River Po and its Lambro tributary, Science for Environment Policy, January 2016.
  • Fishing Po image credit Edizonn.

Risk of pesticide exposure for reptile species in the European Union

One third of all reptile species in EU at high risk of pesticide exposure

Pesticide exposure can have negative impacts on many species and is a major threat to biodiversity.

A new study is one of few to assess the risks specifically for European reptiles.

The results suggest that at least one third of European reptile species are at high risk of exposure, with lizards showing the highest sensitivity to pesticides.


Risk of pesticide exposure for reptile species in the European Union, Science Direct, August 2016.

Turtle & frog image by usfwshq.

Environmental pollution has an especially high impact on wildlife. This is especially the case in industrialized countries. Although, many species within the European Union benefit from protection by the Habitats Directive, no special consideration is given to possible detrimental effects of pesticides. This is in particular remarkable as negative effects, which may lead to a regional diversity loss, have already been identified in laboratory and mesocosm studies.

We conducted a pesticide exposure risk evaluation for all European reptile species with sufficient literature data on the considered biological and ecological aspects and occurrence data within agricultural areas with regular pesticide applications (102 out of 141). By using three evaluation factors – (i) pesticide exposure, (ii) physiology and (iii) life history – a taxon-specific pesticide exposure risk factor (ERF) was created. The results suggest that about half of all evaluated species, and thus at least 1/3 of all European species exhibited a high exposure risk. At the same time, two of them (Mauremys leprosa and Testudo graeca) are globally classified as threatened with extinction in the IUCN Red List of Threatened Species. Variation regarding species occurrence in exposed landscapes between pesticide admission zones within the EU is rather large. This variation is mainly caused by differing land use and species abundances between zones. At the taxonomic level, significant differences in exposure risk can be observed between threatened and non-threatened species, which can be explained by the formers remote distribution areas. Lizards display the highest sensitivity toward pesticides, although no differences in overall ERFs can be observed between taxonomic groups.

By identifying species at above-average risk to pesticide exposure, species-based risk evaluations can improve conservation actions for reptiles from cultivated landscapes.

New tool for the assessment and prioritization of persistence of chemicals under REACH

New computer modelling tool to identify persistent chemicals

Chemicals that persist in the environment can harm humans and wildlife.

This study describes a computer modelling-based approach to predict which chemical compounds are likely to be persistent.

The models were correctly able to predict persistence for 11 of 12 chemicals tested and could provide a cost-effective alternative to laboratory testing.


A new integrated in silico strategy for the assessment and prioritization of persistence of chemicals under REACH, science direct, pii/S0160412015301240, 2013.

The fact that chemicals can be recalcitrant and persist in the environment arouses concern since their effects may seriously harm human and environmental health.

We compiled three datasets containing half-life (HL) data on sediment, soil and water compartments in order to build in silico models and, finally, an integrated strategy for predicting persistence to be used within the EU legislation Registration, Evaluation, Authorisation and restriction of CHemicals (REACH). After splitting the datasets into training (80%) and test sets (20%), we developed models for each compartment using the k-nearest neighbor algorithm (k-NN). Accuracy was higher than 0.79 and 0.76 respectively in the training and test sets for all three compartments. To support the k-NN predictions, we identified some structural alerts, using SARpy software, with a high-true positive percentage in the test set and some chemical classes related to persistence using the software IstChemFeat.

All these results were combined to build an integrated model and to reach to an overall conclusion (based on assessment and reliability) on the persistence of the substance. The results on the external validation set were very encouraging and support the idea that this tool can be used successfully for regulatory purposes and to prioritize substances.

VEGA computer modelling tool to identify persistent chemicals

Chemicals that persist in the environment can harm humans and wildlife

Persistent chemicals (which remain unchanged in the environment for a long time) can accumulate in ecosystems and inside wildlife where they can have damaging effects. People and habitats can remain at risk from these chemicals, even when they are no longer produced, and the substances can also be transported far from their original source.

Under the EU chemicals legislation REACH, all chemicals manufactured or imported above 10 tonnes per year must be assessed for persistent, bioaccumulative and toxic (PBT) properties. Substances are generally assessed based on how easily they biodegrade; chemicals that readily degrade in an experimental test system are considered not persistent. Increasingly sophisticated modelling systems are being developed which can predict the activity of a chemical based on its structure, such as quantitative structure-activity relationship (QSAR) models. These may be particularly efficient when experimental data are not available.

A new integrated in silico strategy for the assessment and prioritization of persistence of chemicals under REACH, science direct, pii/S0160412015301240, 2013.

In this study, collaborators from Germany and Italy describe a novel, integrated approach to assess the persistence of chemicals. The software system, combines multiple computational models to predict persistence in several environmental compartments (e.g. water, soil).

To create the VEGA system, the researchers first used thresholds for ‘persistent’ and ‘very persistent’ substances as defined by REACH, and applied them to the experimental data on the half-life (the time needed to remove half of the starting amount of a substance from the environment) of 12 chemicals in sediment, water and soil. If the half-life of a substance was below the criteria for ‘persistent’ then it was considered ‘not persistent’. A range of sources, including the US Geological Survey, Netherlands National Institute for Public Health and the Environment, the European Chemicals Agency and studies published in journals were used to compile the database of substances with experimental values of persistency.

New computer modelling tool to identify persistent chemicals, Science for Environment Policy, Issue 470, 16 September 2016.

VEGA system is tiered, and involves multiple stages of checks before a prediction is made. First of all, the system checks whether an experimental value (a level of persistence established in previous research) is available for the chemical, as this is generally more reliable than a predicted value. If no experimental value is available, the system checks if the compound is perfluorinated (as these compounds are known to be persistent in the environment). If it is, the chemical is automatically classified as ‘persistent’. If not, the biodegradability of the compound is evaluated using a model. If readily biodegradable, the chemical is classified as ‘not persistent’.

If none of these checks can be carried out, three software models are run on the compound, which predict its persistence in sediment, water and soil: IstKNN, machine learning software, which estimates the activity of chemicals based on similar compounds; SARpy, which automatically identifies structural features of chemicals (‘structural alerts’) that are linked to persistence; and IstCHEMfeat, which separates chemicals into classes based on particular features and chemical groups.

The final assessment is made based on a combination of the predictions and their reliability, and is always conservative (e.g. if a chemical is assessed as ‘very persistent’ in water with medium reliability, but ‘not persistent’ in soil with high reliability, the final outcome will be ‘very persistent’).

After ‘training’ the software using chemicals with known properties, the researchers tested its ability to recognise harmful substances from a set of compounds in the Candidate List of substances of very high concern maintained by the European Chemicals Agency. Of 12 compounds, the persistence of 11 were correctly predicted (the remaining compound could not be assessed as it was too dissimilar to the chemicals used during the training phase). These results suggest this tool could be used to prioritise chemicals for regulatory purposes, such as REACH. It may be a more affordable and speedier alternative to experiments for classifying compounds as ‘persistent’.