Impact of pesticide polarity and lipid phase dimensions on the bioaccessibility of pesticides in agricultural produce consumed with model fatty foods.

For most people, the pesticide residues found on agriculture products are the main source of pesticide exposure, which may adversely influence consumer health. The potential health hazard of residual pesticides depends on the nature of the foods they are consumed with. Studies with fat-soluble vitamins and nutraceuticals have shown that their bioaccessibility depends on food matrix composition and structure. We used an in vitro method to investigate the influence of the dimensions of the lipid phase in model fatty foods (emulsified or bulk oil) on the bioaccessibility of various pesticides. Three pesticides that differed in their oil-water partition coefficients were selected: bendiocarb (log P = 1.7), parathion (log P = 3.8), and chlorpyrifos (log P = 5.3). These pesticides were mixed with tomato puree to represent pesticide-treated agricultural products. Three model foods with different oil phase dimensions were used to represent different kinds of food product: small emulsions (d32 = 0.14 µm); large emulsions (d32 = 10 µm); and, bulk oil. Our results showed that the oil droplets underwent extensive changes as they passed through the simulated gastrointestinal tract due to changes in environmental conditions, such as pH, ionic strength, bile salts, and enzyme activities. The initial rate and final amount of lipid hydrolysis decreased with increasing lipid phase dimensions. Pesticide bioaccessibility depended on both the hydrophobicity of the pesticide and the dimensions of the co-ingested lipid droplets. The least hydrophobic pesticide (bendiocarb) had a high bioaccessibility (>95%) that did not depend on lipid phase dimensions. The more hydrophobic pesticides (parathion and chlorpyrifos) has a lower bioaccessibility that increased with decreasing lipid phase dimensions. Our results demonstrate the critical role that food structure plays on the potential uptake of pesticides from agricultural products, like fruits and vegetables.

A descriptive bibliometric study on bioavailability of pesticides in vegetables, food or wine research (1976-2018).

A bibliometric analysis based on the Web of Science© (WOS) database was performed on bioavailability of pesticides in vegetables, food or wine related studies published from inception to 2018. A total of 1202 articles were subjected to examination. The results reveal that yearly production of scientific articles increased steadily. Journal and institution production, and author's keywords frequencies followed the Lotka's Law. Khan SU and White JC were the most productive authors. The most productive journals were Journal of Agricultural and Food Chemistry (55), and Journal of Ethnopharmacology (48), and the most common WOS subject category was Pharmacology & Pharmacy (419). USA (h-index of 40) produced 21.7 % of all articles, closely followed by China (20.6 %). Chinese Academy of Sciences (34) was the most productive research institutions. Finally, current and future trends in this area should focus on keywords such as pharmacokinetics, curcumin, in-vitro, nanoparticles, oral (bioavailability) and cell.

Behavior of pesticides and their metabolites in traditional Chinese medicine Paeoniae Radix Alba during processing and associated health risk.

In Traditional Chinese Medicine (TCM), crude herbs are processed to obtain the medicinal parts of the plant, from which extracts are prepared for people to take as medicine. However, there is no report on the pesticide residual behavior in Chinese medicines during processing at present, and thus, a systematic study of the effects of different processing factors (PF) on pesticide removal in Chinese medicines and the associated risk of dietary exposure is urgently needed. This study main investigated the dissipation and metabolism of pesticides in Chinese medicine Paeoniae Radix Alba during processing, and the calculated pesticide PFs were also used to assess the risk of dietary exposure. For analyze samples, a simple and high-throughput multiresidue pesticide analysis method was developed and validated for pesticides and their metabolites in P. Radix. based on QuEChERS procedure combined with HPLC-MS/MS. Recoveries at three concentration levels were within 61.37%-117.82% with an associated precision RSD < 15% indicating satisfactory accuracy. TCM processing could be useful for the partial removal of several pesticide residues, with removal rate reaching 98%. The polarity is the dominant variable, which with a high contribution was the effectiveness of the treatment and the concentration factors for pesticides. The hazard quotients of all pesticides were much lower than the safety level, indicating low risk of dietary exposure. Results are of great theoretical and practical value for the scientific evaluation of the safety of Chinese medicines, improvement of the quality and safety level of Chinese medicine.

Caged Gammarus fossarum (Crustacea) as a robust tool for the characterization of bioavailable contamination levels in continental waters: towards the determination of threshold values.

We investigated the suitability of an active biomonitoring approach, using the ecologically relevant species Gammarus fossarum, to assess trends of bioavailable contamination in continental waters. Gammarids were translocated into cages at 27 sites, in the Rhône-Alpes region (France) during early autumn 2009. Study sites were chosen to represent different physico-chemical characteristics and various anthropic pressures. Biotic factors such as sex, weight and food availability were controlled in order to provide robust and comparable results. After one week of exposure, concentrations of 11 metals/metalloids (Cd, Pb, Hg, Ni, Zn, Cr, Co, Cu, As, Se and Ag) and 38 hydrophobic organic substances including polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyles (PCBs), pentabromodiphenylethers (PBDEs) and organochlorine pesticides, were measured in gammarids. All metals except Ag, and 33 organic substances among 38 were quantified in G. fossarum, showing that this species is relevant for chemical biomonitoring. The control of biotic factors allowed a robust and direct inter-site comparison of the bioavailable contamination levels. Overall, our results show the interest and robustness of the proposed methodological approach for assessing trends of bioavailable contamination, notably for metals and hydrophobic organic contaminants, in continental waters. Furthermore, we built threshold values of bioavailable contamination in gammarids, above which measured concentrations are expected to reveal a bioavailable contamination at the sampling site. Two ways to define such values were investigated, a statistical approach and a model fit. Threshold values were determined for almost all the substances investigated in this study and similar values were generally derived from the two approaches. Then, levels of contaminants measured in G. fossarum at the 27 study sites were compared to the threshold values obtained using the model fit. These threshold values could serve as a basis for further implementation of quality grids to rank sites according to the extent of the bioavailable contamination, with regard to the applied methodology.

Vertebrate pesticide risk assessment by indigenous communities in New Zealand.

In New Zealand, the vertebrate pesticide sodium fluoroacetate (Compound 1080) is aerially applied in baits for control of the brush-tailed possum Trichosurus vulpecula (Kerr, 1792). Maori, the indigenous people of New Zealand, have raised concerns about 1080 impacts on culturally-important species. Here, we outline two steps taken to help Maori assess 1080 risk. First, field research was undertaken to determine if naturally-occurring plants utilized by a Maori community for food and medicine would take up 1080 from baits. Single baits were placed at the base of individual plants of two species, pikopiko (Asplenium bulbiferum) and karamuramu (Coprosma robusta). Plants were sampled at various times up to 56 days, and samples were analyzed for 1080 content. No 1080 was detected in any of the pikopiko samples, whereas 1080 was detected in karamuramu, at a maximum concentration of 5 ppb after seven days, and 2.5 ppb after 14 days. This concentration decreased to 0 at 28 days, indicating that 1080 was not persistent. The results of the present study suggest there is negligible risk of humans being poisoned by consuming plants that have taken up 1080 from baits. To allay community concerns that minute concentrations of 1080 might influence the medicinal properties of plants, it is suggested that a withholding period of 30 days after 1080 control operations could be adopted. Second, after further consultation we undertook a review of the scientific literature relating to 1080 impacts on additional non-target species of cultural importance to Maori. The information was presented on an interactive foodweb database that allowed the collection and presentation of a large volume of complex information about 1080 in a holistic and pictorial fashion. This database was presented to many Maori communities throughout New Zealand, and feedback was overwhelmingly positive. The database is likely to play a key role in informing these communities about 1080, and is seen as an important new tool to help these communities make their own risk assessments.

Evaluation of in vitro tests to assess the efficacy of formulations as topical skin protectants against organophosphorus compounds.

Prevention of exposure to the neurotoxic organophosphorus compounds (OP) is a major concern both for pesticide users and soldiers. Skin barrier creams are being developed to complement or replace uncomfortable chemical protective suits. Quick evaluation of formulations efficacy mainly relies on in vitro tests which lead to consistent, complementary and relevant results. The objectives of this work were to determine the consistency of results from in vitro tests and importance of the formulation composition in the skin protective efficacy. The efficacy of three formulations, i.e. oil-in-water and water-in-oil emulsions and perfluorinated compounds-based cream, was evaluated against the OP paraoxon in vitro. Our results indicated that the least effective formulations could be quickly identified by performing in vitro permeation tests with silicone membrane and by evaluating interfacial interactions between formulations and OP. Among the tested formulations, the perfluorinated compounds-based cream could have a broader spectrum of efficacy than emulsions against OP and other toxic chemicals.

Leaf-air transfer of organochlorine pesticides from three selected vegetables.

The leaf-air transfer of organochlorine pesticides (OCPs) in three kinds of vegetables, namely lettuce, romaine and garlic leaves was investigated. It was found that although the uptake of OCPs by the three selected vegetables was similar under controlled conditions, the depuration varied significantly among chemicals and plant species in terms of elimination rate, final residue of each OCPs, as well as the effect of temperature on the residue of OCPs in the vegetables. The results indicated that neither QCB nor HCB could be trapped tightly by any of the three selected vegetables, in contrast, p,p'-DDT could be retained effectively by all of them; the retainment of alpha-HCH, gamma-HCH, p,p'-DDE, was dependent on the vegetable species, of which the garlic leaf had the biggest ability to trap them. Our work provided insight into the behavior of OCPs in the agroecosystem.

Effects of accelerators on mobility of 14C-2,4-dichlorophenoxy butyric acid in plant cuticles depends on type and concentration of accelerator.

Effects of diethyl suberate (DESU), diethyl sebacate (DES), dibutyl suberate (DBSU), dibutyl sebacate (DBS), and tributyl phosphate (TBP) on diffusion of 14C-2,4-dichlorophenoxy butyric acid (2,4-DB) across cuticular membranes (CM) was studied. Astomatous CM were isolated enzymatically from Stephanotis floribunda Brongn. leaves, and diffusion was measured at 20 degrees C. The alkyl-substituted dicarboxylic acids constitute a homologous series with carbon numbers increasing from C12 to C18. Molecular weights increased only moderately from 230.0 (DESU) to 314.5 (DBS), while partition coefficients varied over orders of magnitude from 92 (DESU), to 1213 (DES), to 15,988 (DBSU), to 210,762 (DBS). All the above compounds turned out to be accelerators as they increased 2,4-DB mobility by up to 40-fold with accelerator concentrations in the CM ranging from only 9.2 to 105 g kg(-1). Efficacy (2,4-DB mobility in the presence/mobility in the absence of accelerators) increased with increasing concentrations of accelerators in CM or in reconstituted cuticular waxes. Plotting efficacy vs accelerator concentration in the CM resulted in straight lines, and their slopes increased in the order DBS (0.14), DBSU (0.31), DES (0.51), and DESU (0.85). Hence, DESU was the most powerful accelerator in this series as it increased 2,4-DB mobility in the CM about 6 times more than DBSU. Waxes constitute the major barrier in plant cuticles, and plots of efficacy vs accelerator concentration in Stephanotis wax were also linear, but compared to CM slopes were steeper by factors of 3.20 (DBS), 2.97 (DBSU), 2.70 (DES), and 1.62 (DESU). TBP was similarly effective as DESU, but plots of efficacy vs concentration were not linear, and curves approached a plateau at 60-80 g kg(-1). These data are discussed with regard to suitability of these accelerators for formulating systemic pesticides.

Drawing-up of pesticide selectivity lists to beneficial arthropods for IPM programmes in potato.

In order to promote IPM programmes in potato, the toxicity of 19 fungicides, 4 herbicides and 11 insecticides commonly used in this crop in Belgium was assessed on three beneficial arthropods. These species were representative of the most important aphid specific natural enemies encountered in potatoes: a parasitic wasp--Aphidius rhopalosiphi (De Stefani-Perez) (Hym., Aphidiidae), a ladybird--Adalia bipunctata (L.) (Col., Coccinellidae) and a hoverfly--Episyrphus balteatus (Dipt., Syrphidae). In a first time, pesticides were tested on glass plates on A. rhopalosiphi adults and A. bipunctata and E. balteatus larvae. For each insect, products inducing corrected mortality (Mc) lower than 30% were directly classified in a positive list for harmless products (green list). The other compounds were further tested on plants and listed in toxicity classes according to mortalities induced during this extended laboratory test: harmless (Mc < 30%), slightly harmful (30% < Mc < 60%), moderately harmful (60% < Mc < 80%) and harmful (Mc > 80). A chemical determination of pesticides residues was also performed for each experiment in order to determine the exposure of beneficial arthropods to pesticide residues and to validate the application of chemicals on tested substrates. On the basis of the results of acute toxicity tests, the period of each pesticide use according to normal agricultural practices and the abundance and importance of the three different groups of aphid natural enemies at different periods of the year, four pesticides lists were built up. Each list corresponded to a different period of pesticides application: Period I--from seedling to beginning of June (based on A. rhopalosiphi tests), Period II--beginning to end of June (based on A. rhopalosiphi tests), Period III beginning to end of July (based on E. balteatus and A. bipunctata tests) and Period IV--August to harvest (no exposure of beneficials). Results showed that herbicides were not toxic to the three species and can be used according to normal agricultural practices without restrictions. All fungicides can also be used without restrictions at recommended rates. Only the mixture Metalaxyl-M + Fluazinam was slightly harmful to A. bipunctata but had no effects on A. rhopalosiphi and E. balteatus. Results were more contrasted for insecticides and none of them was totally selective for all the 3 beneficial arthropods. Therefore, they can only be used with restrictions at periods II and III, according to the beneficial species that need to be protected.

Comparative assessment of endocrine modulators with oestrogenic activity. II. Persistent organochlorine pollutants.

Risk assessments of synthetic chemicals with oestrogen-like activity must take into account the high dietary levels of natural endocrine modulators in food. In view of current regulations of the European Union, a hygiene-based margin of safety (HBMOS) for xeno-oestrogens was defined as a quotient of estimated human daily intakes weighted by relative rodent in vivo potencies of the compounds. Such comparisons of intakes and potencies of natural isoflavones, with short half-lives, with those of polychlorinated organic pollutants (POP) displaying significant toxicokinetic accumulation, deserves the special consideration of toxicokinetics. For slowly accumulating compounds such comparison is much more favourable when based on comparative blood and tissue levels, not on scenarios of daily exposures. Observing these principles, the present communication extends the HBMOS concept to POP, using o,p'-DDT, the oestrogenic component of DDT mixtures, as a prototype. An HBMOS of 137 is derived for o,p'-DDT indicative of a sufficient margin of safety to ensure the absence of risk to human health due to its hormonal action, under exposure conditions now prevailing in Western countries.

Toxicokinetics and safety factors in risk assessment.

For risk assessment of anticholinesterase pesticides, acetylcholinesterase inhibition is a sensitive, reversible indicator of exposure. However, use of smaller factors when data are available in human may not be justified in some specific cases. Direct action of anticholinesterase on receptor sites at various cell types in different target organs may yield to the more severe nature of toxicity. At the present time, uncertainties exist due to our limited capability to clarify many human diseases with complex etiology. The toxicokinetic models available may not accommodate some type of toxicants which their mode of action involve haemodynamic change or vascular cell injury. Anticholinesterase pesticides are still widely used in many asian countries to control a variety of pest species in agricultural practices. The physiology of the effects of these agents are complex and appropriate uncertainty or "safety factors" are needed to be acknowledged and taken into account from total exposure. Risk assessment of anticholinesterase agents is related to complex biological system and we will probably, never, at least in our lifetimes, know everything we would like to know to assess risk. We can only do our best with current information available. However, one should be extremely careful and holistic when applying these uncertainties in risk assessment of anticholine-esterase pesticides.