Danbury Tremor and Hatters Shake: Causes, Signs, and Symptoms

This post on Danbury tremor or Hatters shakes tries to include topics related to its causes, signs, and symptoms, sources of mercury poisoning, and a case study. But in short, if you hurdling the question “Danbury tremor is seen in?”, then

Danbury tremor or Hatters shake is seen in the case of mercury poisoning, and it is considered as the key symptom of it. They are often moderately coarse but followed by jerky movements. Moreover, these tremors also are seen in the case of inorganic salts, organic salts, medicine, and drugs of mercury.

What is Danbury Tremor (Hatters Shake)?

Danbury tremor or Hatter’s Shake is one of the key symptoms of mercury poisoning. These tremors are moderately coarse but, these intentional tremors are interspersed by jerky movements.

At the early stages, the patient may not display any sign of hattershake when he/she has a studious work job.

But in the case of prolonged staring, the person starts to have violent tremors and he/she may begin to shake violently.

Other Names of Danbury Tremors and Shakes

Other names of Danbury shakes are:

  1. Hatter shake
  2. Glass blower shake
  3. Intention tremor
  4. Mercurial tremors
  5. Shaking palsy.

Note 1: The term palsy means paralysis. These tremors are also called hatter’s shakes or glass blower’s shakes, as they are common in persons working with mercury in glass-blowing and hat industries.

Why Mercurial Tremor is called to be Hatter’s Shake?

sign of hatters shake

In the 19th century, the manufacturers of hats used rabbit fur. At that time, this city (Danbury) was famous for Abraham Lincoln’s hats.

For manufacturing of these hats, the fur was first made to separate out from the animal pelt with the help of an orange-colored solution that contains mercury nitrate.

But because of poor ventilation, the hatter was used to breathe mercury fumes that majorly lead to chronic mercury poisoning (learn more in the case study section).

Why Mercurial Tremor is called to be Danbury Tremor?

Danbury is a city in Connecticut, USA which was known to be the mass producer of famous hats. In the 19th century, roughly, 5 million hats were produced per year among 56 different factories.

Due to this amount of production, Danbury City was known to be the “hat-making capital” of the world. But with the cost of the health of their workers.

The majority of workers got chronic poisoning by mercury. Moreover, during the course of time—nearly a century— hats were continuously produced using mercury nitrate. Though the use of mercury nitrate was obstructed still, you will find traces of mercury in Danbury, Connecticut outland, soil, and river sediments.

Why Mercurial Tremor is called to be Glass Blower’s Shake?

As per the name, the Glassblower shake name was brought because of the blowing action of glassmakers. Glass bottles or ornamental glassmakers were used to blow mercury compounds to give the desired design. Which later, becomes the cause of mercury intoxication.

That’s the reason why a mercurial tremor is called to be glass-blowers shakes.

Types of Hatter’s Shake/Danbury Tremor

There are two types of Hatter Shakes:

1. Static or Resting Tremors: They generally occur when the patient is at rest with the characteristics of fine trembling most usually in the upper extremities.

2. Intentional or Ataxic Tremor: They occur when there is the intentional movement of extremities or due to the inability to get static tremors.

Why Danbury Tremor is Caused?

It is caused due to mercury poisoning. However, more precisely, these hatter’s shakes are seen in:

  1. Chronic intoxication from inhalation of mercury
  2. Continuous accidental absorption by workers.
  3. Excessive therapeutic use of mercury drug.
  4. Exposure to organic mercury is primarily through the ingestion of mercury-contaminated fish and other seafood.

Sources of Mercury Poisoning

  • Inorganic salts of mercury: chlorides, sulfide, cyanide, oxides, and iodide of mercury.
  • Organic salts: methyl mercury (most toxic), dimethylmercury, ethyl mercury, and phenyl mercury
  • Medicine and drugs: Disinfectant, dental amalgam, and some purgative drugs.
  • Industrial Work: Manufacture of instruments like thermometers, barometers, mercury vapor lamps, explosives, and fireworks.

Mechanism of Hatter’s Shake

It is a three-step mechanism, listed as:

1. Mercury binds with sulfhydryl groups:

Mercury is an organometallic compound which makes it possible to form a covalent bond between mercury and a carbon atom of an organic functional group.

Note 2: Sulfhydryl groups are vital parts of proteins. Sulfhydryl groups generally form a disulfide bridge also called cysteine.

But when mercury binds with sulfhydryl groups it causes enzyme inhibition and also hinders the pathological alteration of cell membranes and their functions.

2. Toxic to CNS

In the case of exposure to metallic mercury, its vapor primarily contains Methyl-mercury, which is primarily responsible for neurological alterations in humans.

It is believed that the mechanisms of action of methyl mercury related to the toxins increase in reactive oxygen species.

It is estimated that oxidative stress may be the cause of these shaking palsy-like neuro-degenerative diseases such as Parkinson’s, and Alzheimer’s disease.

3. Cardiotoxicity

Inorganic mercury may produce profound cardiotoxicity.

Signs and Symptoms of Hatters Shake

  1. These Danbury tremors are first in the hands then progress to lips and tongue, and finally involve the arms and legs.
  2. Progressive personality changes are commonly seen, together with tremors and weakness of the limbs.
  3. Patients might develop gait and balance difficulties.
  4. Patients might develop acute weakness in the lower extremities.
  5. In the advanced stage of Danbury tremor, the person is unable to dress, write legibly, or walk properly.

Danbury Tremors Vs Erethism Mercurialis

Erethism is seen in the chronic phase which is generally from inorganic mercury toxicity.
In this, the patients mainly show irritable, hyperactive, or psychotic behaviors i.e. patient’s mental conditions. These include:

  1. Depression
  2. Anxiety
  3. Amnesia
  4. Insomnia
  5. Extensive irritability
  6. Emotional instability,
  7. Delusions
  8. Hallucinations

Read Other Articles:

Case Study on Danbury Tremor Or Hatter’s Shake

In the 1800s, a hat factory at Danbury was producing around twenty thousand hats annually. And due to its production, Danbury started to be known as “Hat City”.

For the manufacturing of hats, the workers usually use rabbit fur. The fur was first made to separate out from the animal pelt with the help of an orange-colored solution that contains mercury nitrate.

And this process is called carroting. And during the carroting process, workers have to use the orange solution that contains mercury nitrate.

For prolonged exposure to mercury nitrate, the hatters’ workers faced numerous toxic effects on their CNS and mental health.

Symptoms like itching, loss of hair, teeth loss, the blue line in gums (another key sign of mercury poisoning), and uncontrolled muscle twitching which is finally known as “Hatters Shake” or “Danbury Tremor”.

Frequently Asked Questions (FAQ)

Q1. Danbury tremor is seen in which type of poisoning?

Chronic Mercury poisoning.

Q2. What is the other name of Danbury tremors?

Other names of Danbury shakes are hatter’s shakes, glass blower’s shakes, intention tremors, or shaking palsy.

Q3. What are other compounds or chemicals that can cause tremors?

Compounds such as alcohol, phosphorus salts, carbon monoxide, anti-depressants, phenothiazines, caffeine, and theophylline. can cause tremors.

Q4. Danbury’s tremor is first seen in which body part?

Danbury shakes were first starting with hands then progress to lips, tongue, arms, and legs.

Q5. The word “Danbury” in Danbury tremor was named on

Danbury is a city that was earlier popular for hat production. And due to the tremendous production of hats, this city was started to name “Hat City”.

Q6. What is the most serve form of tremors are known as

Concussion Mercurilis.

Q7. What are the other specific diseases related to mercury poisoning?

Mercurialentis: brown reflex of the anterior lens capsule of the eye which can be seen by Slit-lamp examination.
Acrodynia or Pink disease: are mostly in children having pinkish acral rashes
Minamata disease: caused by Organic Contamination like eating fish. It causes disturbances in hand coordination, gait, speech, etc.

Q8. What is the common drug treatment for mercury poisoning?

N-acetyl penicillamine is the chelator agent along DMPS that may improve neurological conditions.


Danbury Tremor’s other names are hatter’s shake, glass blower’s shakes, intention tremors, or shaking palsy. These are due to mercury poisoning.

In the early stage, the person has tremors that start with the hands then progress to lips and tongue, and finally involve the arms and legs. At the advanced stage, a person is neither able to dress nor work or write properly.


  • https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3395437/ [NCBI]
  • https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/mercury-poisoning [ScienceDirect]
  • https://www.sciencedirect.com/science/article/pii/S1382668905000700 [ScienceDirect]

PILLAY, V. V. (2019). Textbook Of Forensic Medicine And Toxicology 2019.

Leave a Comment

Your email address will not be published. Required fields are marked *