Unintended Exposure Research Articles

Evaluating Hazard Symbols for the Globally Harmonized System (GHS) for Hazard Communication

Sweeping globalization has resulted in unparalleled economic growth, including increased international trade of hazardous chemicals. Fundamental differences between nations trading these materials, including language, literacy rates, cultural values, and technical and governmental infrastructures has created an urgent need for a common system of risk communication to reduce the occurrence of deaths and serious injuries that result from unintended chemical exposures. To accomplish this goal, the United Nations (UN) created the Globally Harmonized System for the Classification and Labeling of Chemicals (GHS) in 1992. Unfortunately, there was no requirement for testing of the GHS labeling components, including pictograms intended to depict specific hazards, before their deployment. In Experiment 1, twenty GHS hazard pictograms were subjected to comprehension testing in two non-student samples from the U.S. and Brazil, respectively. In Experiment 2, alternatives for five of the GHS pictograms that were least well understood were created and then re-tested for comprehension. Several of the new pictograms outperformed their “original” GHS counterparts in terms of comprehension and participant preference. Overall, the results of testing showed that only a small portion of the original GHS hazard pictograms reached acceptable levels of comprehension. Therefore, additional systematic work is needed to develop GHS pictogram alternatives that effectively convey safety hazards to a global audience.

Medicine Safety Among Children and Adolescents

An increasing number of studies have documented problems with the safe use of prescription and nonprescription or over-the-counter (OTC) medicines among children and adolescents. Specifically, risks include potential errors by caretakers in administering prescription and OTC medicines to children,1,2 as well as unintended exposure of children and teens to medicines that are not intended for them.3 Children 18 years of age and younger make over 70 000 emergency visits each year for medication overdoses4 whereas adolescents are vulnerable to harm from both unintended and deliberate misuse of medicines.

Estimating Attachment of Nano- and Submicrometer-particles Coated with Organic Macromolecules in Porous Media: Development of an Empirical Model

Assessing the environmental transport and fate of manufactured nanoparticles (NPs) and potential exposure risks requires models for predicting attachment of NPs coated with organic macromolecules in porous media. The objective of this study was to determine the properties of coated nanoparticles that control their attachment behavior. Deposition data for a variety of nanoparticles with different types of anionic organic coatings, including natural organic matter (NOM)-coated latex and hematite nanoparticles, and poly(styrenesulfonate)-, carboxymethylcellulose-, and polyaspartate-coated hematite and titanium dioxide nanoparticles (80 data points), were used to develop an empirical correlation between measurable NP properties and their sticking coefficient (alpha) under a variety of electrolyte conditions and flow velocities. Available semiempirical correlations used to predict the attachment efficiency of electrostatically stabilized (uncoated) NPs overestimate the attachment efficiency of nanoparticles coated with NOM or synthetic polyelectrolytes because the correlations neglect electrosteric repulsions and the decreased friction afforded by such coatings that can inhibit attachment to surfaces. Adding a dimensionless parameter (N(LEK)) representing steric repulsions and the decreased friction force afforded by adsorbed NOM or anionic polyelectrolytes in the correlation significantly improves the correlation. This establishes the importance of including the adsorbed NOM- or polyelectrolyte layer properties for estimating the attachment efficiency of NPs in the environment. The form of N(LEK) suggests that limiting unintended transport and exposure to NPs could be achieved by using coatings with the smallest adsorbed mass and polymer density, shortest extended layer thickness, and largest molecular weight that would still afford the desired functionality of the coating.

Unintended Exposure to Shrimp Allergen: Studies of Cooking Oil used to Deep Fry Breaded Shrimp

Unintended Exposure to Shrimp Allergen: Studies of Cooking Oil used to Deep Fry Breaded Shrimp

Neurogenic-committed human pre-adipocytes express CYP1A isoforms

Stem cell models offer an opportunity both for therapeutic use and for the assessment of alternative in vitro models. Human lipoaspirate is a source of adult stem cells (pre-adipocytes), which are able to differentiate into various phenotypes, such as neurogenic lineage. Here, we analyse the suitability of these in vitro models in screening exogenous compounds, such as environmental pollutants, that may affect adipose cells and neurogenic development. To evaluate neurogenic differentiation, we analysed expression of cholinergic system and acetylcholinesterase immunoreactivity. Heterocyclic derivatives of polycyclic aromatic hydrocarbons (PAHs) are often significant components of environmental contaminants. As they contain inducers of cytochrome P450 1A1 (CYP1A1), we explored the activity of CYP1A1-related enzymes, i.e. 7-ethoxycoumarin- and 7-ethoxyresorufin-O-deethylase (ECOD and EROD) in both cell systems in basal conditions and after exposure to non-cytotoxic doses of beta-naphthoflavone (BNF), a well-known PAH-type inducer. Both cell models showed basal and inducible levels of ECOD. Analysis of CYP1A1 protein expression and EROD-related enzyme activity confirmed the inducibility of the CYP1A1 isoform by BNF. These results demonstrate that mesenchymal adult stem cells can constitute innovative models. We therefore propose the use of pre-adipocytes and their neurogenic derivates to evaluate the cytotoxic/biological effects of unintended exposure to contaminants.

Risks from accidental exposures to engineered nanoparticles and neurological health effects: A critical review

There are certain concerns regarding the safety for the environment and human health from the use of engineered nanoparticles (ENPs) which leads to unintended exposures, as opposed to the use of ENPs for medical purposes. This review focuses on the unintended human exposure of ENPs. In particular, possible effects in the brain are discussed and an attempt to assess risks is performed.Animal experiments have shown that investigated ENPs (metallic nanoparticles, quantum dots, carbon nanotubes) can translocate to the brain from different entry points (skin, blood, respiratory pathways). After inhalation or instillation into parts of the respiratory tract a very small fraction of the inhaled or instilled ENPs reaches the blood and subsequently secondary organs, including the CNS, at a low translocation rate. Experimental in vivo and in vitro studies have shown that several types of ENPs can have various biological effects in the nervous system. Some of these effects could also imply that ENPs can cause hazards, both acutely and in the long term. The relevance of these data for risk assessment is far from clear. There are at present very few data on exposure of the general public to either acute high dose exposure or on chronic exposure to low levels of air-borne ENPs. It is furthermore unlikely that acute high dose exposures would occur. The risk from such exposures for damaging CNS effects is thus probably very low, irrespective of any biological hazard associated with ENPs.The situation is more complicated regarding chronic exposures, at low doses. The long term accumulation of ENPs can not be excluded. However, we do not have exposure data for the general public regarding ENPs. Although translocation to the brain via respiratory organs and the circulation appears to be very low, there remains a possibility that chronic exposures, and/or biopersistent ENPs, can influence processes within the brain that are triggering or aggravating pathological processes.In general, the present state of knowledge is unsatisfactory for a proper risk assessment in this area. Crucial deficits include lack of exposure data, the absence of a proper dose concept, and that studies often fail in adequate description of the investigated ENPs.

Unintended exposure in radiotherapy: Identification of prominent causes

Background and purpose Unintended exposures in radiotherapy are likely to occur when certain conditions that favour such exposures exist. Based on the frequency of occurrence of various causes of 100 events of unintended exposures in radiotherapy as derived from the analysis of published reports, a checklist for assessing the vulnerability of radiotherapy facilities for potential accidents has been prepared. The list presents items to be considered for safety critical assessments of a radiotherapy department for the improvement of patient safety and the entire radiotherapy processes. Materials and methods The resources used for this paper consist of 100 unintended radiotherapy exposures and were derived from existing published reports. The analysis was performed by forming two templates: one consisting of 10 initiating events and another of 35 contributing factors. Results Four most prominent initiating events were identified and together accounted for about 70% of all the unintended exposure events. Ten most prominent contributing factors were also identified and together accounted for about 70% of all the radiotherapy unintended exposure events covered under this study. Conclusion With this knowledge of high frequency of occurrences, the identified four prominent initiating events and the 10 most prominent contributing factors must be checked and dealt with as a matter of priority when assessing the safety of a radiotherapy facility. A simple checklist for checking the quality assurance programmes of a radiotherapy department for every aspect of the design and delivery of radiation have been provided.

Efficient Replication of Factor Returns, June 2009

We present alternative methods for constructing factor mimicking portfolios in practice. We illustrate how portfolios with a limited number of assets and relatively low turnover can be used to track pure factor returns. These portfolios provide an effective instrument to support the practice of investment management. We illustrate how they can be used to hedge out unintended factor exposures of a passive benchmark thus facilitating the optimal management of beta exposure. We illustrate how they can be used to hedge out unintended factor exposures of an active strategy thus isolating pure alpha and facilitating the management of alternative sources of alpha.

Alcohol-Based Hand Sanitizers and Unintended Pediatric Exposures: A Retrospective Review

Alcohol-based hand sanitizers (ABHS) have proliferated throughout the United States in recent years and are now common products in households and hospitals. These products are effective and can reduce absenteeism caused by gastrointestinal illness in elementary school students. The most common ABHS generally use ethyl alcohol as their active ingredient, with concentrations of this compound in the 60% ethanol-by-weight range. Inactive or ingredients are water, isopropyl alcohol, some fragrances, and other emollients. Isopropanol compounds are also occasionally used. Although these agents would not be considered to have a good flavor by most consumers, purposeful abuse to achieve intoxication has been previously reported. In light of the high alcohol concentrations and extraordinary dissemination of these products, we sought to characterize what acute impact, if any, exposure to these products has on young children. To provide a preliminary description in a pediatric population, we studied exposures to ABHS in individuals less than 6 years of age within the Texas Poison Center Network (TPCN) during 2006 and 2007. In 2006 and 2007, there were a total of 826 and 1022 total exposures meeting the study criteria, respectively. Of these exposures, 685 and 792 were in children under 6 years of age, and 621 and 737 exposures were ingestions, 2 and 1 were inhalations, 32 and 20 were ocular, and 30 and 33 were dermal. The type of exposure could not be discerned in 1 case in the 2007 database. Of the entire study population, 55 and 62 sustained a minor effect, and 9 and 11 had effects. Our study demonstrates a paucity of significant effects for exposures related to these products. Since there were no moderate or major effects reported from 1477 children, the product appears relatively safe when misused by this age group. As with many pediatric exposures, the exposures in children under 6 almost invariably occurred as a brief taste or accidental ocular or dermal exposure, thus resulting in little or no toxicity. Of course, significant poisoning and even deaths do occur in children despite this tasting tendency, resulting from substances capable of causing toxicity in low concentrations. Examples of such substances include camphor, sulfonylureas, lead, clonidine, and methylsalicylates. 10 In the setting of young children and ABHS in current formulations, it seems that significant intoxication is extremely unlikely.

Chipped Rail Gear of a Lightwand Device: A Potential Complication of Tracheal Intubation

Laerdal Medical AS, Stavanger, Norway. frode.liland@laerdal.noWe commend Hosokawa et al. and the University Hospital, Kyoto Prefectural University of Medicine, Kyoto, Japan, for the professional actions undertaken relating to patient care and incident reporting after postprocedural discovery of a plastic fragment separated from the rail portion of a Trachlight Tracheal Lightwand handle.Details of the event have been sent to health authorities as prescribed under local country regulations and in accordance with international regulatory agreements. Both the handle and the plastic fragment were forwarded through Laerdal Medical Japan, Ltd., to the device manufacturer, Laerdal Medical AS of Stavanger, Norway, for technical evaluation.Laerdal Medical was pleased to receive advice that no complications or adverse health effects to the patient have been realized. This event has heightened awareness within the reporting institution, and its examination of all similar devices constitutes a responsible protective action. Periodic review of the Trachlight Directions for Use, with special attention paid to cautions and warnings, inspections and functional checks/tests, would be another positive precautionary measure for users.Upon examination of the subject handle, it was observed to have multiple signs of mechanical damage to its other plastic components as well as to the rail teeth. It is likely that the damage exhibited was incurred during its term of institutional use. In addition, microscopic examination revealed residues of unknown chemical origin on another remaining rail gear of the handle.Trachlight handles are made of polycarbonate/acrylonitrile butadiene styrene polymer, a material with many desirable characteristics that is widely chosen for use in medical device applications. However, it is known that exposure to certain chemical compounds can cause it to become brittle. For this reason, a specific caution message appears several times throughout the Directions for Use: “Caution: The lubricant used on the endotracheal tube and the wand should not contain any topical anesthetics or other active ingredients. These chemicals will degrade the plastic in the handle.” Note: The 70% isopropyl alcohol is recommended for cleaning Trachlight handles because it is both compatible with polycarbonate/acrylonitrile butadiene styrene polymer materials and also capable of facilitating removal of noncompatible chemical residuals unintentionally deposited on handles during clinical use.At this time, it is not possible to conclude exactly why the rail tooth broke away from the subject handle, but we believe it is most likely the result of a combination of unintended exposure to some chemicals, and some earlier mechanical impact. Although no trend has been observed for this type of damage, Laerdal will maintain its surveillance of all reports on Trachlight products and continue to promptly investigate any and all incidents related to its devices.In conclusion, we thank Hosokawa et al. for their letter to the editor reporting this occurrence, for providing a constructive product design suggestion, and for raising user awareness, thus reinforcing the importance of familiarity with and adherence to manufacturers’ instructions, cautions, warnings, preuse inspections, and functional tests for any medical device, and the importance to check that all handling processes within the user institution also support such compliance.Laerdal Medical AS, Stavanger, Norway. frode.liland@laerdal.no

Prenatal Testosterone Excess Reduces Sperm Count and Motility

The reproductive system is extremely susceptible to insults from exposure to exogenous steroids during development. Excess prenatal testosterone exposure programs neuroendocrine, ovarian, and metabolic deficits in the female, features seen in women with polycystic ovary disease. The objective of this study was to determine whether prenatal testosterone excess also disrupts the male reproductive system, using sheep as a model system. The extent of reproductive disruption was tested by assessing sperm quantity and quality as well as Leydig cell responsiveness to human chorionic gonadotropin. Males born to mothers treated with 30 mg testosterone propionate twice weekly from d 30 to 90 and with 40 mg testosterone propionate from d 90 to 120 of pregnancy (T-males) showed a significant reduction (P < 0.05) in body weight, scrotal circumference, and sperm count compared with control males. Mean straight line velocity of sperms was also lower in T-males (P < 0.05). Circulating testosterone levels in response to the human chorionic gonadotropin did not differ between groups. These findings demonstrate that exposure to excess testosterone during fetal development has a negative impact on reproductive health of the male offspring, raising concerns relative to unintended human exposure to steroidal mimics in the environment.

Do Risk Factors Eat Alphas?

1. Jyh-Huei Lee 1. A vice president in Research at MSCI Barra in Berkeley, CA. (jyh-huei.lee{at}mscibarra.com) 2. Dan Stefek 1. A managing director in Research at MSCI Barra in Berkeley, CA. (dan.stefek{at}mscibarra.com) Although widespread, the practice in portfolio optimization of using different factor models for risk and alpha has potential pitfalls. Discrepancies between risk and alpha factors can create unintended exposures in optimized portfolios that may hamper performance. An analysis reveals the root of the problem. The optimizer emphasizes the portion of the manager's alpha that is not captured by the risk factors. Aligning the risk and alpha models may lead to better portfolios, even if doing so worsens the overall risk forecasts. In this article, four ways of remedying these problems are presented and compared using familiar optimization problems. The results are promising. TOPICS: [Volatility measures][1], [statistical methods][2], [factor-based models][3] [1]: https://www.pm-research.com/topic/volatility-measures [2]: https://www.pm-research.com/topic/statistical-methods [3]: https://www.pm-research.com/topic/factor-based-models

Transport of exhaled particulate matter in airborne infection isolation rooms

The goal of this research was to examine the characteristics of the spatial velocity and concentration profiles which might result in health care workers’ exposure to a pathogenic agent in an airborne infection isolation room (AIIR). Computational fluid dynamics simulations were performed for this purpose. This investigation expanded on the work of Huang and Tsao [The influence of air motion on bacteria removal in negative pressure isolation rooms. HVAC & R Research 2005; 11: 563–85], who studied how ventilation conditions impact dispersion of pathogenic nuclei in an AIIR by investigating the airflow conditions impacting dispersion of infectious agents in the AIIR. The work included a careful quality assurance study of the computed airflow, and final simulations were performed on a fine tetrahedral mesh with approximately 1.3×10 6 cells. The 1 μm diameter particles were released from a 0.001225 m 2 area representing the nose and mouth. Two cases were investigated during the current study: continuous exhalation of pathogen-laden air from the patient and expulsion of pathogenic particles by a single cough or sneeze. Slow decay of particle concentration in the AIIR during the single cough/sneeze simulation and tendency for particle accumulation near the AIIR walls observed in the continuous breathing simulation suggest that unintended exposures are possible despite the ventilation system. Based on these findings, it is recommended that extra care be taken to assure proper functionality of personal protective equipment used in an AIIR.

Evaluation of Centrally Acting Cholinesterase Inhibitor Exposures in Adults

There are 4 centrally acting cholinesterase inhibitors (CA-ChEI) available in the US: tacrine, galantamine, rivastigmine, and donepezil. Documented clinical experience involving exposure to these agents is limited. The lack of information makes decisions involving excessive or unintended CA-ChEI exposure difficult. To assess the effects, demographics, and outcomes of CA-ChEI exposures reported to US poison centers. A retrospective review of the Toxic Exposure Surveillance System of the American Association of Poison Control Centers data of acute and acute-onchronic exposures involving only a CA-ChEI in patients 19 years of age or older with documented medical outcomes from 2000-2005 was performed. There were 1026 records that met criteria for this study. Patients aged 70-89 years made up 73% of reports; 69% of the patients were female. Moderate (197) and major outcomes (20) accounted for 21% of exposures. There were no deaths. Clinical effects that occurred in 5% or more of patients included vomiting (34%), nausea (28%), diarrhea (12%), dizziness/vertigo (9.9%), drowsiness/lethargy (7.7%), diaphoresis (7.4%), tremor (5.2%), and bradycardia (5%). Patients were admitted to the hospital in 19% of all exposures. Of those patients, 42% were admitted to a critical care unit. The majority (65%) of exposures were attributed to unintentional therapeutic error. Patients received at least one form of therapy in 47% of exposures, including intravenous fluid (111), antiemetic (48), atropine (17), benzodiazepine (15), oxygen (14), antihypertensive (4), pralidoxime (4), intubation (3), antihistamine (2), antiarrhythmic (1), anticonvulsant (1), and pacemaker (1). The majority of patients evaluated in this retrospective study experienced no or mild effect; however, significant or life-threatening effects were observed in a small group of patients and an appreciable number of patients were admitted to a healthcare facility.

Probabilistic risk assessment model for allergens in food: sensitivity analysis of the minimum eliciting dose and food consumption

Previously, TNO developed a probabilistic model to predict the likelihood of an allergic reaction, resulting in a quantitative assessment of the risk associated with unintended exposure to food allergens. The likelihood is estimated by including in the model the proportion of the population who is allergic, the proportion consuming the food and the amount consumed, the likelihood of the food containing an adventitious allergen and its concentration, and the minimum eliciting dose (MED) distribution for the allergen. In the present work a sensitivity analysis was performed to identify which parts of the model most influence the output.A shift in the distribution of the MED reflecting a more potent allergen, and an increase in the proportion of the population consuming a food, increased the number of estimated allergic reactions considerably. In contrast, the number of estimated allergic reactions hardly changed when the MEDs were based on a more severe response, or when the amount of food consumed was increased.Development of this work will help to generate a more accurate picture of the potential public health impact of allergens. It highlights areas where research is best focused, specifically the determination of minimum eliciting doses and understanding of the food choices of allergic individuals.

Defense against dermal exposures is only skin deep: significantly increased penetration through slightly damaged skin

The OECD guideline for studies on percutaneous penetration to be used in hazard and risk evaluations prescribes experimental conditions with optimal barrier integrity of the skin, which in many occupational settings probably is not true. Thus, workers may have compromised skin due to chemical or mechanical damage, due to different medical conditions (eczema, dermatitis, skin irritation) or related to occupational scenarios involving prolonged wet work. The present study used the OECD guideline procedures to study the in vitro percutaneous penetration through human skin of a number of model substances (glyphosat, caffeine, benzoic acid, malathion) covering a range of solubilities. Further, we studied the extent to which a slightly damaged skin would change the rate, the amount absorbed during dermal exposure and the distribution of chemical deposition between epidermis and dermis. The present study demonstrates that a limited damage to the skin significantly increases the permeability coefficient (K (p)) as well as total percutaneous penetration of chemicals, and most significantly for those compounds that due to their physicochemical characteristics (the most hydrophilic as well as the most lipophilic) have low penetration rates through intact skin. The present experiment not only confirms the proportionality between lipophilicity and potential for percutaneous penetration, but also illustrates that at a certain degree of lipophilicity of a model compound, the different skin compartments become more attractive for temporary deposition of model compounds. Moreover, a clear change from epidermal deposition towards a dominating dermis deposition of chemicals temporarily deposited within the skin is seen following damage to the skin barrier. Thus, the distribution of chemicals within the skin compartments is affected by the physicochemical characteristics of the chemicals as well as by the integrity of the skin. This observation may have implications when evaluating the possibility of removing chemicals from the skin through different cleansing procedures following unintended dermal exposures.

Implications of Diphenhydramine Single-Dose Unintended Ingestions in Young Children

Diphenhydramine is frequently used in children, but the consequences of single unintended dose exposures in young children are unknown. We evaluated 2000-2001 American Association of Poison Control Centers-Toxic Exposure Surveillance data on children exposed to diphenhydramine ingestions. Nine hundred twenty-six cases met the inclusion criteria; 49.1% were men, mean age was 29.7 +/- 13.0 months (range, 1-72 months). Approximately 85% of unintentional exposures occurred in 1- to 3-year-old children. The mean dose ingested was 6.4 +/- 6.1 mg/kg (median, 4.6 mg/kg). Thirty-two percent of patients were symptomatic: minor (29.4%), moderate (2.9%), and severe (0.11%). There was no relationship between dose and symptom severity. Diphenhydramine dose ingestion of 7.5 mg/kg or greater was not a predictor of severity (P = 0.47) The relationship between ingested dose and severity of symptoms was insignificant.

Risk assessment and food allergy: the probabilistic model applied to allergens

In order to assess the risk of unintended exposure to food allergens, traditional deterministic risk assessment is usually applied, leading to inconsequential conclusions as ‘an allergic reaction cannot be excluded’. TNO therefore developed a quantitative risk assessment model for allergens based on probabilistic techniques resulting in a more exhaustive risk assessment and more detailed information. By now, this approach is recognized as the future approach in allergen risk assessment. A case study (hazelnut proteins in chocolate spread) is presented as a proof of concept.

Antiretroviral Therapy at Conception in Pregnant Women with HIV in Italy: Wide Range of Variability and Frequent Exposure to Contraindicated Drugs

Data from a large national surveillance study was used to describe antiretroviral regimens in pregnant women with HIV, with particular reference to the presence at conception of antiretroviral treatments contraindicated in pregnancy. Therapeutic changes during pregnancy were also analysed. Among 334 women on antiretroviral treatment at conception, less than half (42.4%) reported current pregnancy as planned. A large number of different regimens (80) was observed. All the regimens included at least one nucleoside or nucleotide reverse transcriptase inhibitor. Non-nucleoside reverse transcriptase inhibitors and protease inhibitors were present in similar proportions (39.2% and 40.7%, respectively). The most commonly used drugs were lamivudine (83.2% of regimens), zidovudine (50.0%), stavudine (d4T; 38.0%), nevirapine (25.7%), didanosine (ddl; 17.7%) and nelfinavir (17.7%). Treament with efavirenz (13.5% of regimens) and ddl+d4T (9.6%) was markedly frequent. Use of efavirenz at conception was associated with a subsequent treatment change during pregnancy (odds ratio [OR]: 13.2.; 95% confidence interval [CI]: 3.2-53.8, P < 0.001). A similar but less strong association was found for ddl (OR: 1.8; 95% CI: 1.03-3.25, P = 0.033), whereas being on nevirapine was associated with a lower risk (OR: 0.58; 95% CI: 0.38-0.81, P = 0.013). Our data show that treatment at conception frequently represents the regimen previously selected for the treatment of the non-pregnant woman. The observed rates of exposure to contraindicated treatment should lead prescribing physicians to consider in HIV-positive women therapeutic choices that take into account the likelihood of an unplanned pregnancy. Such an approach is likely to reduce not only unintended exposures to contraindicated drugs, but also therapeutic changes during pregnancy.

Reporting overexposures and unintended exposures in diagnostic procedures

Legislation requires the reporting to regulatory authorities of incidents in which patients have been exposed to ionizing radiation to an extent "much greater than that intended". The authorities have published guidance on what is considered to meet this requirement. However, there is still some confusion regarding, particularly, the necessity to report some unintended doses. It is believed that there is a disproportionate amount of resource spent investigating some unintended exposures because all such exposures will have an effective overexposure factor of infinity, irrespective of the magnitude of the dose and the associated risk. This paper proposes changing the definitions of "overexposure" and "unintended exposure" and the adoption of a reporting process based upon risk assessment. All records and data would be collected and, if required, reported, but investigation of individual incidents would take place only for incidents carrying a greater risk than 1 in 10,000.