Biocides at home: emissions, potential exposure and reduction solutions – BiocidAtHome

To understand how these products are used, we analysed national regulatory sales databases. We also conducted surveys at points of sale (supermarkets, DIY stores), amongst professionals – particularly in the construction sector – and directly in people’s homes to understand their practices and perceptions of risk.

To assess biocide contamination in the domestic environment, several complementary media, known as matrices, were studied: air, dust and greywater, i.e. domestic wastewater excluding blackwater. These matrices play different roles. Air and dust are indicators of direct exposure experienced by occupants, whilst greywater serves as an indicator of the transfer of biocides from homes to receiving environments (soil, rivers, lakes, etc.) via the sewerage system.

The uses of biocidal substances:

Inside homes, biocidal substances are found in various products, either as preservatives or active ingredients: household products, cosmetics, pest control products, veterinary products, etc.

Outside homes, biocides are also widely present in everyday products. They are incorporated into building envelopes – facades, roofs, structural timber or waterproofing membranes – and are intended to protect materials, improve their durability or prevent the growth of moss, fungi or roots. These uses are part of routine construction, renovation or maintenance activities, without always being identified as potential sources of pollution.

Whether used inside homes or outdoors, biocidal substances are part of routine practices, closely linked to standards of hygiene, cleanliness, comfort and building protection. Surveys of households highlight a low level of awareness of the risks: the fact that a product is on the market tends to be interpreted as an implicit guarantee of safety, thereby relegating health and environmental impacts to the background.

Environmental contamination:

The findings of the Biocid@Home project show that indoor environments are contaminated with biocidal substances linked to the use of household products. These substances are then released into the environment via the sewerage system, as wastewater treatment plants are not very effective at removing them.

As for runoff from buildings, the biocides released are also discharged into receiving environments, either directly or via rainwater infiltration.

Reducing household chemicals: a public health issue still evolving:

Whilst certain uses are essential for hygiene, health or the protection of materials, these findings raise questions about the necessity of other uses. For these substances, which are not significantly reduced by conventional treatment in wastewater treatment plants, reduction at source through changes in usage and practices therefore appears to be a complementary tool for limiting both human exposure and the deterioration of the chemical quality of the environment. However, the effectiveness of this solution is necessarily limited, given the multitude of behavioural changes required of individuals and their varying social and financial capacity to adopt certain standards. Our considerations at the level of the individual and their practices must now be extended to other instruments and a mix of public policies to be implemented to limit the release of biocidal substances into the environment.

The project offers a range of prospects.In the field of environmental chemistry, there are plans to expand the existing databases and even add certain biocides under study to the lists of substances regularly monitored in indoor air and surface water. Research into the effectiveness of greywater and rainwater management systems in removing biocides could be further explored at demonstration sites. In the field of humanities and social sciences, we will examine the development and reception of public policies for controlling micropollutants at source in homes. Our analysis at the level of the individual and their practices will be extended to other instruments and combinations of public policies to be implemented.

The Biocid@Home project brings together multiple disciplines (chemistry, hydrology, modeling, economics and social sciences) to characterize and reduce the health and environmental impacts of biocides. Biocides are contaminants of emerging concern that are widely used at home. Biocidal substances are ubiquitous in the urban habitat; they are used as preservatives in daily products such as cosmetics, detergents, paints or textiles, biocides in building materials, pesticides against insects or mites, etc. These toxic substances pose a double threat on two distinct levels. On the one hand, humans are routinely exposed to biocides at home, which increases health risks, including sensitization, antibiotic resistance or cancers. On the other hand, these biocides may be released into the environment through wastewater or runoff, thus inducing a potential impact on aquatic and terrestrial ecosystems and a deterioration of the resource quality. Despite this alarming situation, the urban/domestic sources of biocides, contrary to the agricultural pesticides, have been overlooked in terms of health and environmental risk assessment. The overall objective of the Biocide@Home project is to identify evidence-based strategies to reduce emissions of urban biocides. To reach this objective, we propose to pursue the following specific aims: (i) to determine biocide emissions by the urban habitat by measuring biocide emissions at the building scale in indoor air, greywater and runoff; (ii) to assess the health and environmental risks related to these emissions by modelling the fluxes, transfer/transformation processes and environmental exposure at the urban scale and by assessing the health and environmental risk linked to these emissions and transfers; and (iii) to compare the efficiency and socio-economic impact of potential solutions designed to reduce exposure. Specifically, we propose to study "at source" solutions, i.e. decentralized treatments (phyto-purification of greywater and infiltration trenches for runoff) and reduction of emissions by changes in practices (consumption, maintenance, etc.). These novel “at source” solutions will be compared to global solutions, i.e. regulation for ban or substitution of substances, and centralized treatments in wastewater treatment plants. The success of this ambitious project is guaranteed by the extensive experience and expertise of the PI and her team, the state-of-the art LEESU facilities in analytical chemistry, and the access to experimental devices in two pilot sites, which are heavily instrumented. The study team assembled (LEESU, ANSES, INERIS, UMTEC) has unique, multidisciplinary expertise with combined experience in biocide studies, environmental sampling and analytical chemistry, modeling, environmental and health risk assessment, sociologic studies of the changes in practices, and socio-economic approach of the different forms of public actions in the mitigation of emerging contaminants. The expected results are the development of novel methods for transformation products with High Resolution Mass Spectrometry (HRMS), indoor analysis and modeling of contaminants transfer from the building scale to the city scale. A public database of biocide concentrations in indoor air, greywater, runoff, groundwater and surface water will be produced. Data on exposure will be linked to health and environmental risks. The efficiency of greywater phytopurification, runoff infiltration and changes in inhabitant practices will be assessed and discussed. Regarding the protection of receiving environments, our project will give key information allowing the prioritization of levers of actions between wastewater and stormwater, and between domestic and building materials sources. By combining our multidisciplinary results, this project will provide vital information to help refining future forms of public actions regarding the control of emerging contaminants and their impact on health and the environment.