By The Associated Press – Six people who died at a Colorado dairy farm this summer were exposed to hydrogen sulfide gas, authorities said Thursday.
The Weld County coroner’s office drew its conclusions from autopsies and toxicology tests.
The deaths of five men and a teenager on Aug. 20 sent shockwaves through the rural communities in and around Keenesburg, 35 miles northeast of Denver, where emergency responders entered a confined space to recover the bodies.
Authorities had immediately expressed concern that the deaths were linked to harmful gases.
The coroner’s findings will factor into an investigation by federal workplace safety and health investigators into determining what happened at the industrial-scale dairy, owned by California-based Prospect Ranch, as well as the role of a dairy equipment contractor.
What happened at the dairy farm
Dairy operators and federal workplace safety authorities have said little about what went wrong.
The hazards of confined spaces on farms and dairies are a well-known and persistent cause of death in agriculture across the U.S. — often from exposure to odorless and colorless noxious gases, or due to asphyxiation in closed spaces where oxygen has been depleted.
All those who died in Colorado were Latino, ranging in age from 17 to 50. Four of them, including the teenage high school student, were from the same extended family.
Why confined spaces are dangerous
Silos that store grain and feed are among the most deadly confined spaces on farms, with hazards that include gases from fodder for feeding cattle that ferments and releases carbon dioxide and nitrogen oxide …
Background …
“Hydrogen sulfide is immediately dangerous to life and health …”
Safety Risk from Manure Storages of Dairy Cows Bedded with Gypsum
Findings from on-farm monitoring of dairies using gypsum as stall bedding show a link has been found to highly toxic levels of hydrogen sulfide gas during manure movement and agitation.
College of Agricultural Sciences
The Pennsylvania State University
Updated: March 22, 2023
Gypsum recycled from manufacturing and construction waste provides a bedding source for the dairy industry. Gypsum can be used as a bedding additive to traditional bedding materials.
Gypsum and Manure Gas Hydrogen Sulfide
Gypsum is calcium sulfate (CaSO4·2H2O) so it provides a source of sulfate, which under anaerobic conditions can be microbially converted to hydrogen sulfide (H2S) gas.
Anaerobic conditions (without oxygen) exist in dairy manure slurry within many short-term and most long-term storages.
Hydrogen sulfide is heavier-than-air. It therefore settles in low areas such as in pits, near storages, and in the breathing zones of calves and children. When present, H2S is released in bursts that are dangerous to nearby humans and cattle during manure movement or agitation.
Be aware that sources of sulfate in manure, other than gypsum bedding, are possible via poor water quality (high sulfur content) or animal feed ingredients.
Hydrogen sulfide is immediately dangerous to life and health above 100 ppm. Lower concentrations of 10 to 20 ppm can be tolerated for periods of time, such as a part of a workday. Hydrogen sulfide gas has a familiar “rotten egg” odor to a healthy human nose.
Unfortunately, this distinctive odor goes undetected at dangerous levels or after extensive exposure. Because of this, instruments are needed to detect H2S concentrations to avoid dangerous conditions … SOURCE.
