Acute Effects of Brevetoxin-3 Administered via Oral Gavage to Mice

Brevetoxins (BTXs) constitute a family of lipid-soluble toxic cyclic polyethers mainly produced by Karenia brevis, which is the main vector for a foodborne syndrome known as neurotoxic shellfish poisoning (NSP) in humans. To prevent health risks associated with the consumption of contaminated shellfish in France, the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) recommended assessing the effects of BTXs via an acute oral toxicity study in rodents. Here, we investigated the effect of a single oral administration in both male and female mice with several doses of BTX-3 (100 to 1,500 µg kg-1 bw) during a 48 h observation period in order to provide toxicity data to be used as a starting point for establishing an acute oral reference dose (ARfD). We monitored biological parameters and observed symptomatology, revealing different effects of this toxin depending on the sex. Females were more sensitive than males to the impact of BTX-3 at the lowest doses on weight loss. For both males and females, BTX-3 induced a rapid, transient and dose-dependent decrease in body temperature, and a transient dose-dependent reduced muscle activity. Males were more sensitive to BTX-3 than females with more frequent observations of failures in the grip test, convulsive jaw movements, and tremors. BTX-3's impacts on symptomatology were rapid, appearing during the 2 h after administration, and were transient, disappearing 24 h after administration. The highest dose of BTX-3 administered in this study, 1,500 µg kg-1 bw, was more toxic to males, leading to the euthanasia of three out of five males only 4 h after administration. BTX-3 had no effect on water intake, and affected neither the plasma chemistry parameters nor the organs' weight. We identified potential points of departure that could be used to establish an ARfD (decrease in body weight, body temperature, and muscle activity).

Residual pesticides in grape leaves (Vitis vinifera L.) on the Egyptian market and human health risk

A QuEChERS method, followed by GC-MS/MS and LC-MS/MS was used for determining more than 400 pesticide residues in grape leaves collected from the Egyptian markets during the 2021 summer season. Seventy-eight samples contained 36 pesticide residues of different chemical groups above the EU-MRLs. Fungicides were the most frequently detected pesticides (59%), followed by insecticides (35%) and herbicides (5%).Hazard Quotients and Hazard Indexes were calculated where the results showed that both do not pose any health risk to consumers. Furthermore, cumulative risk assessment parameters (cHI) according to pesticide chemical group were calculated, resulting in 0.06, 0.09, 0.20, 0.28, 0.7 and 1.1% for strobin, organophosphorus, neonicotinoid, pyrethroid, benzimidazole and azole compounds, respectively. Fungicides were the major contributors to cHI, above insecticides by a factor of 2.7. Hence, there is a need for continuous survey and monitoring to protects consumers from exposure to unauthorized substances such as carbendazim, benomyl and profenofos.

An analysis of the setting of the acute reference dose (ARfD) for pesticides in Europe

To protect human health, acute reference values have been established for pesticides which have the potential to cause a toxic effect after acute human exposure. These values are used to identify exposure levels below which there is no appreciable risk. Comprehensive reference documents, including OECD criteria, are available to aid identification of relevant toxicological endpoints. Within Europe, there is a concern that the identification process is inconsistent and unnecessarily conservative such that safe products with no established human health risk are being restricted. For this reason, the basis for the setting of an acute reference dose (ARfD) has been investigated for 130 pesticides to better understand how the toxicological endpoints are selected. The investigation has shown that most ARfDs are derived from repeat dose studies and that there is an over-representation of prenatal developmental toxicity studies. There is clear evidence that ARfDs derived from rabbit developmental toxicity studies are set over conservatively with regard to acute maternal effects and often inappropriately. To facilitate an improved system, refinements to the existing process are recommended, the use of maternal data in the rabbit as the basis for deriving an ARfD is critically evaluated and a new, more pragmatic approach to ARfD derivation is proposed.

National short-term dietary exposure assessment of a selected group of pesticides in Argentina

An evaluation of acute dietary exposure to pesticide residues, applying deterministic and stochastic methods, was performed for a selected group of pesticides in two representative age groups from Argentina. Thus, 28 active ingredients (a.i.) and 75 food items were evaluated for the group of 2-5-year-old children, while 9 a.i. and 59 food items were considered for the 10-49-year-old women group. A deterministic assessment was conducting following the Food and Agriculture Organization (FAO) and World Health Organization (WHO) procedure but using the national maximum residue limits (MRLs) as pesticide residue concentration data, while in the stochastic approach, a theoretical distribution modeled with the available information was used. Food consumption data were obtained from the 2004-2005 comprehensive national nutrition and health survey. The risk was estimated by comparing the short-term dietary exposure with the acute reference dose (ARfD) values for each pesticide-food combination evaluated. In the deterministic assessment, 173 (39.1%) and 40 (31.3%) combinations exceeded the ARfD thresholds for the 2-5-year-old children and 10-49-year-old women groups, respectively. This conservative study generated relevant information as a first stage of acute dietary risk assessment in Argentina.

A TTC threshold for acute oral exposure to non-genotoxic substances

To derive an acute TTC threshold, the correlation between Allowable Daily Intakes (ADIs, chronic values) and Acute Reference Doses (ARfDs) of pesticides evaluated in the EU was investigated and their distributions were compared. The correlation between ARfDs and ADIs was significant (p = 0.01), but weak (r(2) = 0.051). Consequently, using this approach to derive acute TTC values does not seem valid. Therefore, the distributions of ARfDs and ADIs were compared directly, in order to extrapolate from chronic to acute TTC values. This comparison made for the combined Cramer structural class II and III pesticides showed a ratio ARfD/ADI of approximately 3 at the fifth percentile of the distributions. Based on these results, it is justified to propose a TTC for acute effects for Cramer III substances by multiplying the Cramer class III TTC threshold of 90 μg/person/day with a factor 3. This leads to an acute TTC threshold based on the Munro dataset for Cramer class III substances of 270 μg/person/day.

Does EU legislation allow the use of the Benchmark Dose (BMD) approach for risk assessment?

Hazard characterisation is largely based on an approach of (statistically) comparing dose groups with the controls in order to derive points of departure such as no-observed-adverse-effect levels (NOAELs) or lowest-observed-adverse-effect levels (LOAELs). This approach suggests the absence of any relevant effect at the NOAEL. The NOAEL approach has been debated for decades. A recent Scientific Opinion by the European Food Safety Authority (EFSA) concluded that the Benchmark Dose (BMD) approach should be preferred over the NOAEL approach for deriving human (health-based) limit or guidance values. Nonetheless, the BMD approach is used infrequently within European regulatory frameworks. The reason for this may lie in legislation or guidelines requiring the use of the NOAEL approach. In this context, various EU regulatory frameworks were examined on such demands. Interestingly, no single legislation was identified containing statutory requirements in conflict with the use of the BMD approach.

Complex mixtures: relevance of combined exposure to substances at low dose levels

Upon analysis of chemically complex food matrices a forest of peaks is likely to be found. Identification of these peaks and concurrent determination of the toxicological relevance upon exposure is very time consuming, expensive and often requires animal studies. Recently, a safety assessment framework based on the Threshold of Toxicological Concern (TTC) was published to assess the safety of chemically complex matrices more efficiently. In this safety assessment framework, the toxicological relevance of exposure to unidentified substances in chemically complex food matrices can be related to the Cramer class III TTC threshold, currently set at 90 μg/day. However, possible additive or synergistic effects of combined exposure is not covered. The current evaluation describes the relevance of combined low dose exposure to unidentified substances in chemically complex food matrices. It is concluded that to some extent cumulative effects at exposure levels for each substance at or below the Cramer class III TTC threshold, being present in a complex mixture including food, might occur. However the health relevance of possible cumulative effects at this dose level is considered to be that low that a need for a correction factor to cover possible cumulative effects is very low to absent.