# Amyotrophic Lateral Sclerosis (ALS)-Related Mortality Among World Trade Center-Exposed and Non-World Trade Center-Exposed Rescue and Recovery Workers

## TL;DR

This study found that World Trade Center-exposed rescue workers did not have higher rates of ALS-related deaths compared to non-exposed workers or the general population.

## Contribution

The study provides new evidence on ALS mortality risk among WTC-exposed workers using a large cohort and standardized mortality ratios.

## Key findings

- ALS mortality rates were lower in WTC-exposed workers compared to non-exposed workers (RR = 0.54).
- ALS-related mortality was not elevated in WTC-exposed workers compared to the general US population (SMR = 0.44).
- No significant increase in ALS mortality was observed in either WTC-exposed or non-exposed groups.

## Abstract

Amyotrophic lateral sclerosis (ALS) is a rare but fatal neurodegenerative disease. Some occupational exposures are associated with ALS. This study evaluated ALS mortality rates in World Trade Center (WTC)-exposed and non-WTC-exposed rescue/recovery workers. Fire department workers who were 18–70 years old on 11 September 2001 (9/11) were included in the study (N = 33,122). Follow-up began on the later of 9/11 or on their hire date, and ended at the earliest death date or 31 December 2023. Cause of death data were obtained from the National Death Index; ALS (specifically motor neuron disease)-related mortality was the primary outcome. Demographic data were obtained from the fire departments’ databases. We estimated standardized mortality ratios (SMRs) and 95% CIs for ALS-related mortality in WTC-exposed and non-WTC-exposed workers using US population rates as a reference. Multivariable-adjusted Poisson regression models estimated relative rates (RRs) and 95% CIs for ALS-related mortality in the WTC-exposed vs. non-WTC-exposed groups. Between 9/11 and 31 December 2023, five WTC-exposed and sixteen non-WTC-exposed participants died of ALS. ALS mortality rates were lower in WTC-exposed than in non-WTC-exposed rescue/recovery workers (RR = 0.54, 95% CI = 0.49–0.60). ALS-related mortality was not elevated in WTC-exposed (SMR = 0.44, 95% CI = 0.14–1.03) or non-WTC-exposed rescue/recovery workers (SMR = 1.06, 95% CI = 0.60–1.72) compared with the US general population. This initial evaluation of ALS in WTC-exposed workers indicates that the risk of ALS death is not increased in this population.