Abstract:
Background: Within six weeks of the first case of COVID-19 in early Dec 2019 in Wuhan, China, the pandemic had already a foothold half-way around the world in Washington State, where the the first case of COVID-19 in the United States was confirmed on 20 Jan 2020 in a traveler returning from the index city. A number of public health measures were instituted in the US to counter the spread of disease, to include the intensified use of cleaning chemicals and disinfectants to prevent the spread of SARS-CoV-2 virus. With the increased use of and exposure to such chemicals comes the commensurate risk of increased toxic inhalation injury incidence, as suggested by US and Canadian national poison control center surveillance data, comparing the number of calls made to poison centers before and during the COVID-19. However, these data did not differentiate non-occupational from occupational exposures, the latter of which might result in greater exposures, more serious injury and a higher economic burden. Based on these and similar studies and public health recommendations and policies that likely resulted in increased exposure to cleaners and disinfectants, we hypothesized that workers in Washington State may have experienced an increase in toxic inhalation injuries and work-related asthma due to cleaners and disinfectants during the COVID-19 pandemic.
Methods: We conducted a retrospective cohort study of Washington State workers’ compensation (WC) claims filed between 2017 and 2022 to assess the temporal relationship between claims filed for toxic inhalation and work-related asthma to cleaning and disinfectant agents and the COVID-19 pandemic. Data elements included chemical exposure, occupational, and industry codes; sex and age of worker on date of injury; date and calendar quarter of injury; claim status; if a claim involved hospitalization, disability, or fatality; time-loss days; claim costs. Descriptive statistics were tabulated both by era and by quarter. Using full-time equivalent (FTE) data and total quantity of WC claims information by quarter, incidence rates between the pre-pandemic and pandemic groups were calculated, and a statistical analysis of the incidence rate ratios or incidence risk ratios was performed, using the two-sample inference for incidence-rate and chi-squared test of differences in proportions, respectively.
Results: Surveillance data identified 486 unique WC claims involving inhalational exposures to cleaners and disinfectants out of 798,436 total WC claims. The pre-pandemic era comprised 12 quarters within the period 1 Jan 2017 – 31 Dec 2019 with 295 claims, and the pandemic era comprised 10 quarters within the period 1 Jan 2020 – 31 Mar 2022 with 191 claims. When comparing the pandemic era with pre-pandemic era, the incidence rate of cleaner-disinfectant inhalational claims based on total FTE decreased 21% from 4.2 per 100,000 FTE to 3.3 per 100,000 FTE (IRR 0.79, 95% CI 0.66 – 0.95, p = 0.013). Incidence risk based on total workers’ compensation claims decreased by 11% from 6.4 per 10,000 to 5.7 per 10,000 (IRR 0.89, 95% CI 0.74 – 1.07, p = 0.22). Incidence risk based on total toxic inhalation claims increased by 27% from 0.13 to 0.16 (IRR 1.27, 95% CI 1.07 – 1.50, p = 0.007). When comparing the first quarter of the pandemic against the same quarter in the preceding year, the incidence rate of cleaner-disinfectant inhalational claims based on total FTE increased by 76% from 3.90 per 100,000 FTE to 6.85 per 100,000 FTE (IRR 1.76, 95% CI 1.04 – 2.96, p = 0.032). Incidence risk based on total workers’ compensation claims increased by 84% from 6.1 per 10,000 to 11.3 per 10,000 (IRR 1.84, 95% CI 1.09 – 3.10, p = 0.020). Incidence risk based on total toxic inhalation claims increased by 58% from 0.12 to 0.19 (IRR 1.58, 95% CI 0.96 – 2.59, p = 0.066). Descriptive statistics indicated that some occupations filed proportionately more claims in the pandemic era than in the pre-pandemic era (Management, Sales and Related, Construction and Extraction, Transportation and Material Moving) while other occupations filed proportionately fewer claims (Food Preparation and Serving Related, Personal Care and Services); some industries filed proportionately more claims in the pandemic era than in the pre-pandemic era (Retail trade, Transportation and Warehousing, Educational Services). Conclusions: These results indicate an increase in inhalational occupational exposures and injuries to cleaning and disinfectant chemicals in the early phases of the COVID-19 pandemic in Washington State, consistent with trends seen in previous studies. Review of claims records corroborate a number of contributing factors, such as hazardous application methods and inadequate hierarchy of controls. Continuing occupational surveillance and efforts to identify root causes for toxic inhalation injuries are critical to informing future public health policies and organizational procedures surrounding the safe use of cleaning and disinfecting agents, balanced with the public health promoting activities of cleaning and disinfection of the workplace.