Humans and wildlife are exposed to hundreds of chemicals at varying doses every day, for example in the air we breathe, the water we drink, the food we eat and from the consumer products we use. Typically, we assess the risks of chemicals by considering exposure to individual chemicals and their effects. In reality, organisms are exposed to many chemicals simultaneously and sometimes chronically or frequently over long durations. Some would say that the existing system to assess the risks of individual chemicals is adequate to protect us from our exposures to different chemicals simultaneously, so long as exposure of each chemical is controlled below a certain dose. Others argue that when exposed to multiple chemicals, their combined action on the body as a whole can lead to harmful effects that are not evaluated by the current methods. Examples of adverse outcomes in humans are an increased risk of reproductive effects, metabolic and endocrine disorders such as diabetes, or increased incidence of cancer. Chemical mixtures in the environment can also adversely affect ecological species such as fish, birds and mammals, in terms of their normal reproduction, growth and population numbers.
There are many questions for the scientific research community to answer that will aid the development of more effective policy and regulation. These include questions around monitoring and measurement methods – are current methods effective or are there improvements to be made. The modelling of source-pathway-receptor exposure routes is often uncertain, for example as to how chemicals travel from air, water and soil and into the body, and at what concentrations. Many assumptions are made – can these be refined by better measurement? Other questions are around how to identify and characterise adverse effects that may be caused, ameliorated or exacerbated by the presence of multiple chemicals in the body simultaneously. Is there an increased risk of adversity that we are not adequately addressing by current policy and regulation, or is the current system of risk assessment and risk management adequate for health protection goals? Chemistry is relevant to all of these questions, and we will ask what should be the focus of future chemical sciences research to provide the right types of evidence to inform policy and decision making.
There are many questions for the scientific research community to answer that will aid the development of more effective policy and regulation. These include questions around monitoring and measurement methods – are current methods effective or are there improvements to be made. The modelling of source-pathway-receptor exposure routes is often uncertain, for example as to how chemicals travel from air, water and soil and into the body, and at what concentrations. Many assumptions are made – can these be refined by better measurement? Other questions are around how to identify and characterise adverse effects that may be caused, ameliorated or exacerbated by the presence of multiple chemicals in the body simultaneously. Is there an increased risk of adversity that we are not adequately addressing by current policy and regulation, or is the current system of risk assessment and risk management adequate for health protection goals? Chemistry is relevant to all of these questions, and we will ask what should be the focus of future chemical sciences research to provide the right types of evidence to inform policy and decision making.
Themes
In this symposium, we shall consider the following questions:- What are the gaps in our knowledge as to the sources and quantities of the (potentially hazardous) chemicals present in air, soil, water, food and consumer products?
- What are the gaps in our knowledge as to how living systems are exposed and affected by multiple and simultaneous chemical exposures at the chemical & biological interface?
- How can we assess the real level of risk from multiple and simultaneous exposures to hazardous chemicals via multi-causal perturbations of biology in humans & wildlife?
- How can the chemical science community perform research and generate fit-for-purpose evidence to enable policy and chemicals regulation to be developed for chemical mixtures (that aims to adequately protect public health & the environment whilst at the same time realises the beneficial use of chemicals for society)?
- Substances that are mixtures themselves according to ECHA definitions within REACH (i.e. multi-constituent substances (MCS); materials of unknown or variable composition, complex reaction products or biological materials (UVCB))
- Products that contain more than one chemical, e.g. cosmetics, biocidal or plant protection products
- Chemicals jointly emitted from production sites, during transport processes, and consumption or recycling processes
- Several chemicals that might occur together in environmental media (water, soil, air), food items, biota and human tissues, as a result of emission from various sources, via multiple pathways.
