International prevalence of chemical hypersensitivity, co-occurrence with asthma and autism, and impact of perfumed consumer products
Abstract
Context and Purpose
Chemical hypersensitivity is a medical condition characterized by adverse health effects resulting from exposure to common pollutants and chemicals. This study analyzed the prevalence of chemical hypersensitivity in four countries: United States (US), Australia (AU), Sweden (SE) and United Kingdom (UK). In addition, the co-occurrence of chemical hypersensitivity with medically diagnosed multiple chemical hypersensitivity syndrome (MCS), odor sensitivity, asthma and autism/autism spectrum disorder (ASD) was examined.
Results and Conclusions
The results showed that in the countries studied, an average of 19.9% of the population reports chemical hypersensitivity, 7.4% have a medical diagnosis of MCS, 21.2% report one or the other, and 32.2% report noxious odor sensitivity. These symptoms often co-occur – among those with MCS, 55.4% have concurrent asthma and 13.5% have autism/ASD. Due to exposure to perfumed products in the workplace, as many as 28.6% of people with hypersensitivity have lost workdays or employment in the past year. The study proves that the problem is global and involves tens of millions of people.
1. introduction
Multiple chemical hypersensitivity (MCS) is an increasingly serious challenge for modern public health and occupational medicine. The syndrome manifests as a wide range of symptoms from the nervous, respiratory, cardiovascular or skin coating systems, among others, in response to very low doses of commonly used chemicals. Among the most serious incendiaries are cleaning products, synthetic fragrances, cosmetics and air fresheners. Despite the huge impact on patients’ quality of life, there is still no standardized policy for diagnosing this ailment in many countries around the world.
Although previous national surveys, particularly in the United States, have estimated the prevalence of MCS at several percent, a comprehensive analysis internationally has been lacking. The purpose of this study is to determine the current prevalence rate of MCS in the adult population in four developed countries, to analyze in detail the phenomenon of the co-occurrence of this syndrome with diagnoses of asthma and autism spectrum disorders, and to quantify the social and occupational losses resulting from exposure to synthetic fragrances.
2 Survey Methodology
To ensure the highest reliability of the data from the four separate countries, the survey was based on a standardized statistical instrument using nationally representative demographic panels.
The random survey sample included adults aged 18 to 65+ years. The distribution of participants was as follows: United States (n=1137), Australia (n=1098), United Kingdom (n=1100) and Sweden (n=1100). The panel structure was carefully controlled to reflect the demographic parameters of each nation in terms of gender, age and geographic region.
Data was collected using CAWI (Computer-Assisted Web Interviewing). Respondents were asked about the presence of hypersensitivity to chemicals, having an official medical diagnosis of MCS, asthma or autism, and sensitivity to fragrance compositions. Questions also addressed the impact of the nuisance on occupational functioning – including possible loss of work days due to odors.
Confidence intervals (95% CI) were determined for the prevalence of the phenomena studied in the general population and for subpopulations (e.g., the percentage of asthmatics who react negatively to odors). Analysis of variance and correlation coefficients were developed to assess whether the relationships between MCS, asthma and autism show statistically significant differences across continents.
3. results (Tabular Section)
The full raw results, divided into five subject areas, showing the intensity of the phenomena in question in all four countries and the aggregate average, are collected below.
Table 1: Prevalence of chemical hypersensitivity and medical MCS diagnoses in the general population
| Reported Condition | US (%) | Australia (%) | UK (%) | Sweden (%) | Average (%) |
|---|---|---|---|---|---|
| General chemical hypersensitivity | 25.9 | 18.9 | 16.3 | 18.5 | 19.9 |
| Medically diagnosed MCS | 12.8 | 6.5 | 6.6 | 3.6 | 7.4 |
| One and/or the other (combined) | 27.5 | 19.9 | 18.0 | 19.5 | 21.2 |
Table 2: Co-occurrence – Asthma and Asthmatic States.
| Category | US (%) | Australia (%) | UK (%) | Sweden (%) | Average (%) |
|---|---|---|---|---|---|
| General population suffering from asthma | 35.0 | 32.9 | 39.7 | 31.4 | 34.8 |
| Percentage of asthma patients among those with MCS | 59.2 | 56.5 | 57.0 | 49.0 | 55.4 |
Table 3: Co-occurrence – Autism and ASD (Spectrum Disorders).
| Category | US (%) | Australia (%) | UK (%) | Sweden (%) | Average (%) |
|---|---|---|---|---|---|
| Total population with autism diagnosis | 8.2 | 8.2 | 10.1 | 5.4 | 8.0 |
| Percentage of autism diagnoses in people with MCS | 13.3 | 13.0 | 16.2 | 11.3 | 13.5 |
Table 4: Sensitivity to perfumed products (Fragrance Sensitivity).
| Category | US (%) | Australia (%) | UK (%) | Sweden (%) | Average (%) |
|---|---|---|---|---|---|
| Severe hyperreactivity to odors in the general population | 34.7 | 33.0 | 27.8 | 33.1 | 32.2 |
| Response to odors in people with a diagnosis of MCS | 81.0 | 82.6 | 77.7 | 86.8 | 82.0 |
Table 5: Economic impact and ailments that hinder function
| Impact of exposure to chemicals or odors (Among the MCS population) | Average Submissions (%) |
|---|---|
| Health ailments leading to permanent or temporary incapacity/disability | 44.1 |
| Loss of working days or job position in the past year solely due to exposure to odors in the office | 28.6 |
4 Discussion and Main Conclusions
The data presented above demonstrate the striking scale of the problem. In the four leading developed countries, an average of one-fifth of the population (19.9%) suffers from the health effects of hypersensitivity to ubiquitous chemical pollutants. This translates in absolute numbers to more than 61 million patients in these regions. Although the prevalence of MCS shows some statistical variation at the national level (ranging from 16.3% in the UK to 25.9% in the US), the determinants of its co-occurrence (co-prevalence) with asthma and autism are statistically almost identical everywhere.
Special attention should be paid to the results for high-risk groups. More than half of those reporting respiratory system burden also exhibit painful, multisystem reactions to detergents and perfumes. A similar, inextricable correlation has been captured along the nervous system-neurotoxicity line for patients on the autism spectrum, for whom odor-saturated environments are biologically intolerable.
Conclusions and environmental guidelines:
- Huge social cost: With 28.6 percent of MCS patients having had to quit their jobs, take unpaid leave or lose assignments, hypersensitivity to artificial fragrances generates massive losses for the national GDP and labor market.
- Urgent paradigm shift in space design: the study’s author stresses the firm need for the immediate implementation of “fragrance-free” standards (completely odor-free zones) in workplaces, schools, health care facilities and public institutions.
- Threats from cosmetics and chemicals: Since common consumer cosmetics masked by synthetic fragrances cause severely disabling conditions in 44.1% of patients, reducing their emissions is a public safety issue today.
Reference references include previous population studies by the author herself from 2018 (on perfume emissions from consumer cosmetics) and reviews of hypersensitivity at the level of individual states from previous years, cited in the paper.
The full text of the original article is publicly available in the Springer Link database at: https://link.springer.com/article/10.1007/s11869-019-00672-1
Data dostępu: 28.04.2026