Wednesday, November 28, 2012

IRSST Management of Occupational Manganism: Consensus of an Experts’ Panel



IRSST Management of Occupational Manganism:

Consensus of an Experts’ Panel

Occupational manganism



Pg 25

"Few scientific data are available on the reversibility of the neurotoxic effects associated with  chronic Mn overexposure. The researchers believe that the effects are rather irreversible (Ellenhorn  and Barceloux 1988). However, there is some evidence that recovery may occur when the exposure stops (Smyth et al. 1973). Antiparkinson drugs such as levodopa may be able to reverse some of the neuromuscular signs of manganism (Ejima et al. 1992; Rosenstock et al. 1971), but these drugs have several side effects, and reports indicate that they do not improve the patients’ neurotoxic symptoms (Calne et al. 1994; Chu et al. 1995; Cook et al. 1974; Ellenhorn and Barceloux 1988; Haddad and Winchester 1990; Huang et al. 1989). The ATSDR review (2000) reports that symptoms of manganism can be improved by certain medical treatments, but the improvement is generally temporary and damage to the brain permanent.

Huang et al. (1993, 1998) documented the progression of manganism in five workers chronically exposed to Mn in the ferroalloy sector. Their results show that the disease continues to progress even 10 years after leaving the workplace. Roels et al. (1999) carried out an eight-year longitudinal study on the same cohort as that published in 1992 in order to determine the reversibility of three early neurotoxic effects: hand-eye coordination (HEC), hand steadiness (HS), and simple visual reaction time (SVRT). They concluded that the tests used were reproducible and reliable throughout the study. They also demonstrated that past severity of Mn exposure determined the relative significance of the loss in precision in hand and forearm movement (HEC) in exposed workers as compared to the control group as well as their recovery potential. However, for the two other tests, HS and SVRT, no recovery was noted, suggesting that these conditions are irreversible.

However, when neurological damage is measured, it could be reversible but could also worsen over time, even in the absence of occupational exposure. As a result, it is important to intervene as rapidly as possible, in a phase that is possibly still reversible. Then, any significant additional exposure to manganese or to any other neurotoxic agent could contribute to the acceleration in the progression of the disease."

MORE QUOTES


"...concentration at which no effect (NOAEL) should occur on the CNS or pulmonary system of healthy workers. This level is 0.07 mg Mn/m3 in respirable dust and represents an average exposure level for a healthy worker.

Based on the level of scientific knowledge and for practical reasons, the experts agreed on the  following recommendations for keeping workers with manganism at work or for returning them to work when medical conditions permit: the occupational exposure to manganese should be kept as low as possible and should be accompanied by a ceiling value, a value never to be exceeded of 0.03 mg/m3, measured in respirable dusts. This value is based on the ATSDR established NOAEL. The ATSDR value of 0.07 is divided by 2 and, rather than being an average value for the work shift, it is converted to a ceiling value. Since the ATSDR level has been established for healthy workers, the experts concluded that half this value, 0.03 mg/m3, evaluated in respirable dusts and never to be exceeded should not be detrimental to the health of the confirmed (definite and probable) or suspected (possible) diseased worker and should be applied to all those cases where medical diagnosis is such that the worker is judged capable of returning to or staying at work."

NLM - United States National Library of Medicine - Tox Maps

NLM - United States National Library of Medicine 
Tox Maps Environmental Health E-Maps 
Finding the correct map and related information can be pesky.  Instructions for finding Ashtabula and On-site information from which the information below was taken. 
 Go to:  SEARCH.  Check small box, over search, TRI.  Fill in Ashtabula, Ohio 44004
   Begin Search.
Go to:  Right side of page menu.  Click TRI Facility Details.
A list will appear in the Right menu with links to facilities.  More information is available as you scroll down the page.  
At the bottom of the page you will see:

All chemicals reported by this facility link opens in new window

On-site release summary for this facility link opens in new window
  Click these for more information, still.  


Millenium Inorganic Chemicals & A Cristal Company
In this case we are looking at Millenium, which has two facilities exactly contiguous with each other.  Individually, each is a heavy emitter of Manganese.  Together they are really scary. 

This was not an accident. 




Historical summary 1


Historical summary 2


EPA - Manganese (IRIS) Integrated Risk Information System


Manganese (IRIS) Integrated Risk Information System

 
Iris Risks
Among the primary effects associated with Mn toxicity from inhalation exposure in humans are signs and symptoms of CNS toxicity. The first medical description of chronic Mn neurotoxicity (manganism) in workers is generally credited to Couper in the 1830s (NAS, 1973). Although the course and degree of Mn intoxication can vary greatly among individuals, manganism is generally considered to consist of two or three phases (Rodier, 1955). The first is the psychiatric aspect, which includes disturbances such as excessive weeping and laughing, sleep disturbance, irritability, apathy, and anorexia. These symptoms can occur independently of the second phase, neurological signs. The latter may include gait disturbances, dysarthria, clumsiness, muscle cramps, tremor, and mask-like facial expression. In addition, there may be a final stage of Mn intoxication involving symptoms of irreversible dystonia and hyperflexion of muscles that may not appear until many years after the onset of exposure (Cotzias et al., 1968). Cotzias et al. (1976) noted a parallel between these stages of symptoms and the biphasic pattern of dopamine levels over time in the Mn-exposed individuals noted above. Indeed, various specific features of Mn toxicity show biphasic patterns in which there is generally first an increase then a decrease in performance (e.g., a notable increase in libido followed by impotence, or excitement followed by somnolence) (Rodier, 1955).
Pg 25
Nogawa et al. (1973) investigated an association between atmospheric Mn levels and respiratory endpoints in junior high school students. A questionnaire focusing on eye, nose, and throat symptoms and pulmonary function tests were given to students attending junior high schools that were 100 m (enrollment = 1258) and 7 km (enrollment = 648) from a ferromanganese plant. Approximately 97-99% of the students participated. Based on measurements obtained at another time by a government agency, the 5-day average atmospheric Mn level 300 m from the plant was reported to be 0.0067 mg/cu.m.
Significant increases in past history of pneumonia, eye problems, clogged nose, nose colds, throat swelling and soreness, and other symptoms were noted among the students in the school 100 m from the plant. Those living closest to the plant reported more throat symptoms and past history of pneumonia than did students living farther away. Pulmonary function tests revealed statistically significant decreases in maximum expiratory flow, forced vital capacity (FVC), forced expiratory volume at 1 second (FEV-1), and the FVC:FEV- 1 ratio in the students attending the school closer to the plant, with some measures suggesting a relationship between performance and distance of residence from the plant.
Evidence for Human Carcinogenicity
__II.A.1. Weight-of-Evidence Characterization
Classification — D; not classifiable as to human carcinogenicity
Basis — Existing studies are inadequate to assess the carcinogenicity of manganese.
__II.A.2. Human Carcinogenicity Data
None.

Welding Rod Dangers - Progression and Recovery


Manganism progression and recovery


FROM:  Welding Rod Dangers

Finding a Cure: The Quest for New Manganism Treatments

Patients in the early stages of manganese poisoning or manganism may be exhausted, weak, depressed, and headachy. Some researchers believe that the disease is reversible at this point, provided the patient is no longer exposed to manganese. These early manganism symptoms look a lot like signs of other conditions. Therefore, if you are a welder with health problems, you should check with your doctor and explain about your manganese exposure. Once more serious signs of manganism appear, such as awkward gait and tremors, it may be too late to stop the progression of the disease. Removing the source of manganese may no longer be helpful.

Doctors have used edetate calcium disodium (EDTA) as a manganism treatment. EDTA is a chelating agent, which means it binds metals into stable cyclic compounds. This is thought to lower their toxic effects and enhance their excretion from the body. One 1957 study used EDTA, caramiphen hydrochloride (an anticonvulsant ), mephenesin (a muscle relaxant), and a vitamin C preparation to treat a miner with motor problems, hallucinations, and other signs of manganese poisoning. He recovered nicely (Arch Neurol. 2000 Apr; 57(4): 597–9; Arch Ind Health. 1957; 16:64–66).

In 1996, a Japanese researcher reported the case of a 55–year old woman with a moving tremor, unsteady gait, high manganese levels in her blood and urine, and an MRI scan consistent with a diagnosis of manganism. She responded well to EDTA, and an MRI scan after this manganism treatment showed a lessening of the brain pattern typical of manganism patients (Rinsho Shinkeigaku, 1996 Jun; 36(6): 780–2). An Italian study, again on only one patient, also showed the value of EDTA in manganism treatment (Neurotoxicology 2000 Oct; 21(5): 863–6).

Chinese researchers reported on two manganism patients who were given sodium paraaminosalicylic acid (PAS sodium), a drug used along with other medications to treat tuberculosis (Br J Ind Med. 1992 Jan; 49(1): 66–9). One manganism patient was considered cured and the other’s symptoms were lessened.

These studies are encouraging, but limited by the small number of patients treated and the lack of control groups. More work needs to be done to see if PAS sodium or EDTA are truly effective and safe manganism treatments. If they prove valuable, even more tests would be necessary to determine proper dosage and to deal with any side effects. Meanwhile, the best way to treat manganism is to recognize it early, before it becomes irreversible, and to remove the patient from the source of manganese exposure.