Deadly chocolate factory blast highlights combustion risks

Mar 28, 2023, 1:42 PM

Last week’s fatal blast at a Pennsylvania chocolate factory highlighted the combustibility of food plants in general and chocolate making in particular.

The powerful explosion at 75-year-old R.M. Palmer Co. — which makes chocolate eggs, bunnies, bars, coins and other treats — killed seven, sent 10 to the hospital and damaged several other buildings in West Reading, a small town 60 miles (96 kilometers) northwest of Philadelphia, where it has long had a factory.

Local, state and federal investigations are ongoing. Pennsylvania State Police said “everything’s on the table,” as smelled natural gas before the blast, although the gas utility UGI said it received no reports of a gas leak.

A look at some of the hazards of food manufacturing and what may have been behind this fatal blast:


In general, commercial ovens and furnaces, commercial refrigerant using ammonia and combustible dust produced by ingredients like cocoa powder and corn starch are primary explosive hazards at food plants, according to Holly Burgess, technical lead for industrial and chemical safety at the National Fire Protection Association, a nonprofit group that produces hundreds of codes and standards.

“Most people, if you’ve not been in any sort of food manufacturing, you don’t understand what your hazards are and what you’re looking at,” Burgess said.

Chocolate companies and other food manufacturers must take steps to mitigate the risk of fire and explosion from dust. Smaller particles that stay aloft pose a greater danger than bigger particles that quickly fall to the floor.

“It is a common concern at many food production facilities handling fine combustible particulates,” said Bob Zalosh, a retired professor at Worcester Polytechnic Institute and a consultant on industrial fire and explosion hazard mitigation and investigations.

Food manufacturers are supposed to determine the combustibility of the dust, perform a hazard analysis and then take steps to manage it, adhering to the fire protection association’s standard for preventing dust explosions in food processing plants.

Common methods for controlling dust include dust collectors and industrial vacuum cleaners.


One possible explanation for the blast is an explosion of highly flammable powdered starch, which candy companies often use to cast chocolate into shapes such as Easter eggs, said Terry Wakefield, a business consultant and food scientist who used to run a manufacturing facility that supplied chocolate to R.M. Palmer.

The shock wave from an initial explosion could have jarred any dust accumulated on ceilings and other surfaces, he said. “And now you end up with a massive amount of starch, which combusts, and those explosion clouds move faster than sound and they have unbelievable force,” said Wakefield, who made his assessment after watching video of the explosion that was captured by a TV station’s weather camera.

“A lot of people don’t realize that starch could do that sort of thing,” he said.

Based on the kinds of candy Palmer makes, the company likely used the starch-casting method, according to Wakefield.

Officials at the family-owned company have not responded to questions from The Associated Press.

Dust explosions have long been a problem in manufacturing. Between 1980 and 2017, nearly 400 combustible dust fires and explosions killed 185 people and injured more than 1,000 across multiple industries, including food, chemical, paper, pharmaceutical and metal processing, according to the U.S. Chemical Safety Board.

In 2008, an accumulation of sugar dust ignited and blew up the Imperial Sugar plant in Port Wentworth, Georgia, killing 14.


At least two workplace accidents have happened at Palmer since 2018, according to federal records.

The U.S. Occupational Safety and Health Administration, which regulates workplace safety, visited Palmer’s West Reading plant in 2018, when an employee lost the tip of a finger while cleaning a pressurized valve. The company agreed to pay a $13,000 fine.

In 2019, OSHA investigated an accident at Palmer’s plant in nearby Wyomissing, Pennsylvania, when a conveyor belt was turned on while a worker was cleaning a roller, according to federal records. The employee’s arm was broken in multiple places. The company settled with OSHA for $26,000.

And in January, records show, OSHA levied a penalty of more than $12,000 after an inspection at the Wyomissing plant. Details of that case were not available.

The online records did not say anything about combustible dust, or any other explosive hazard at Palmer.


A woman who lived next door to the plant filed suit Tuesday, alleging Palmer was negligent in failing to maintain its equipment and prevent the blast. Betty Wright was “lifted from her feet and blown across the room,” suffering injuries to her neck, back, hip and leg, the suit said. She also lost belongings.

A statement from Wright’s lawyers at Morgan & Morgan said the firm has put together a “team of experts so we can understand what caused this catastrophic explosion.”

Additional lawsuits are expected.

United States News

Associated Press

After losing Houston mayor’s race, US Rep. Sheila Jackson Lee to seek reelection to Congress

HOUSTON (AP) — Two days after losing her bid to be Houston’s next mayor, longtime U.S. Rep. Sheila Jackson Lee announced on Monday she will seek a 16th term in Congress in 2024. Jackson Lee first took office in 1995. Her district includes downtown Houston and some of the city’s historically Black neighborhoods, including 3rd […]

9 minutes ago

A Bible rests on the lawn of Community Baptist Church amongst storm debris Monday, Dec. 11, 2023, i...

Associated Press

Two Nashville churches, wrecked by tornados years apart, lean on each other in storms’ wake

NASHVILLE, Tenn. (AP) — After a March 2020 tornado destroyed the Rev. Jacques Boyd’s Nashville church, his friend, the Rev. Vincent Johnson, lent him space to worship in. Nearly four years later, Boyd has offered to return the favor for the exact same reason. “Whatever we have is available to them,” said Boyd, who leads […]

38 minutes ago

Associated Press

The US is restricting visas for nearly 300 Guatemalan lawmakers, others for ‘undermining democracy’

MIAMI (AP) — The Biden administration announced on Monday that it would impose visa restrictions on nearly 300 Guatemalan lawmakers, private sector leaders and their families it accuses of “undermining democracy and the rule of law.” Guatemala faces mounting criticism by world leaders and watchdogs accusing it of attempts to block progressive president-elect Bernardo Arévalo […]

2 hours ago

Associated Press

Texas woman who sought court permission for abortion leaves state for the procedure, attorneys say

AUSTIN, Texas (AP) — A pregnant Texas woman who sought court permission for an abortion in an unprecedented challenge to one of the most restrict bans in the U.S. has left the state to obtain the procedure, her attorneys said Monday. The announced came as Kate Cox, 31, was awaiting a ruling from the Texas […]

2 hours ago

Associated Press

Ramaswamy was the target of death threats in New Hampshire that led to FBI arrest, campaign says

CONCORD, N.H. (AP) — A New Hampshire man has been accused of sending text messages threatening to kill a presidential candidate ahead of a scheduled campaign event Monday, federal prosecutors said. The U.S. Attorney’s office did not name the candidate. However, a spokesperson for Republican candidate Vivek Ramaswamy said Monday that the texts were directed […]

3 hours ago

Associated Press

Man filmed wielding folding chair in riverfront brawl pleads guilty to misdemeanor

MONTGOMERY, Ala. (AP) — A man filmed swinging a folding chair during an Alabama riverfront brawl this summer pleaded guilty to a misdemeanor disorderly conduct charge Monday. The guilty plea resolved the last of the charges brought in connection with the brawl. The man was ordered to perform community service and given a suspended sentence. […]

3 hours ago

Sponsored Articles

Follow @KTAR923...

Valley residents should be mindful of plumbing ahead of holidays

With Halloween in the rear-view and more holidays coming up, Day & Night recommends that Valley residents prepare accordingly.

Follow @KTAR923...

The 2023 Diamondbacks are a good example to count on the underdog

The Arizona Diamondbacks made the World Series as a surprise. That they made the playoffs at all, got past the Milwaukee Brewers in the NL Wild Card round, swept the Los Angeles Dodgers in the NLDS and won two road games in Philadelphia to close out a full seven-game NLCS went against every expectation. Now, […]

Follow @KTAR923...

West Hunsaker at Morris Hall supports Make-A-Wish Foundation in Arizona

KTAR's Community Spotlight this month focuses on Morris Hall and its commitment to supporting the Make-A-Wish Foundation in Arizona.

Deadly chocolate factory blast highlights combustion risks