I think that solder sitting molten in a solder pot oxidizes. Freshly heated solder included with flux is virtually oxide free, and the smoke from the flux is... smoke... not smoke with oxide "dust".
The tip of your iron has such oxides AFTER it sits with a drop of solder on it after a while. That's what the purplish discolorations are. New solder, particularly that which is bathed in flux has no oxides. Oxides take time, exposed to OXYGEN to form, and they do not immediately start roaming around in the air.
You're a hypochondriac, and the other guy is a speculative dope.
I know some people can't help themselves (especially when posting anonymously) but when a poster resorts to fact-free personal attacks, I take as symptomatic that he lacks confidence in the factual content of the position he is posting and is hoping to drive any rebuttals away with unpleasantness.
So let's look at the last post: interesting... If I understand it correctly, when working with a lead-alloy solder, there is no hazard as long as one avoids bringing the alloy into contact with heat and oxygen.
Good question, actually; it's on the order of 10**-11 torr, really hard vacuum. And vapor pressure of lead/tin solder will be lower, there's some boiling-point elevation due to the 'impurity'.
To get up to soft-vacuum range (10**-3 torr) you have to take lead to
620C :== 1148F.
See Rev. Sci. Instr _19_, 920 (1948) by R. R. Law, for more details.
Him being a hypochondriac is obvious. At least to anyone with an IQ over 40.
You're a goddamned idiot.
Wrong again, asswipe. You conveniently left out more than a few factors.
1) For one thing, even a solder pot takes a while for "dross" (Lead oxides, idiot) to form, and that occurs when there is *no* flux present. It also occurs in a steady state, and does not put any "dust" into the air, unless some total retard is tossing it up like a salad. Even when it is dragged to the side of the solder pot, it stays IN the pot.
2) A soldering iron should only have solder on it when performing a soldering operation. Otherwise, it should have been wiped clean, and be shut off. So there won't be any "dross" to speak of on the solder tip. And that leaves us with:
3) When said iron IS in use, there is almost certainly flux present, and when the flux is present, the Oxygen is not. Why do you think solder joints are 100% free of dross and have perfect microcrystalline structures?
Clue: It isn't because they are forming Lead oxides, much less Lead oxide dust!
For reference, 525F :== 274C, 600F :== 315C, and the MSDS claims health significance to Pb vapor starts at 500C :== 930F.
Solder pots to tin wire by burning off the insulation are kept hotter than that, and soldering irons routinely are used at 800F for some kinds of operations (desoldering, mainly). Thermostats can fail and temperatures in gas-torch soldering can get high enough.
However: any normal room has LOTS of surfaces in contact with air, all of which will condense out any vapor because they're cooler than the 500C temperature. It isn't normal outside a smelter to have a working environment that has significant Pb vapor pressure, because the work environment doesn't consist mainly of hot-solder surfaces and lungs.
The most important danger in soldering: you might pick up the iron by the barrel. That hurts.
OSHA comments from the January 19, 1989 Final Rule on Air Contaminants Project (extracted from 54FR2332):
"OSHA previously had no limit for rosin core solder pyrolysis products. Based on the ACGIH TLV, the Agency proposed an 8-hour TWA of 0.1 mg/m3 for these compounds, measured as formaldehyde. OSHA has determined that a TWA limit of 0.1 mg/m3 is necessary to prevent workers from experiencing severe irritant reactions, and the Agency is including this limit in i ts final rule. This limit applies to the thermal decomposition products of gum rosin soldering flux (3 to 6 percent rosin and 30 to 70 percent tin-lead solder)(Lozano and Melvin, unpublished data, as cited in ACGIH
1986/Ex. 1-3, p. 514).
"A two-week exposure of guinea pigs and rats to these products at average concentrations of 0.96 mg/m3 caused reduction in rate of weight gain in male guinea pigs, abnormal liver-to-body-weight ratios in guinea pigs of both sexes, and abnormal heart-to-body-weight ratios in male rats (Industrial Bio-test Lab, Inc., as cited in ACGIH 1986/Ex. 1-3, p. 514). Lungs of the animals exposed in this same study were hyperemic.
"In humans, slight bronchial irritation has been reported at 1 mg/m3 (Industrial Bio-test Laboratories, Inc. 1967, as cited in ACGIH 1986, p. 514). Several workers who were chronically exposed to levels as high as 0.15 mg/m3 had to be removed from exposure because of intractable upper respiratory tract irritation; when concentrations were kept below 0.1 mg/m3, such irritation was not reported (Christy
1965, as cited in ACGIH 1986/Ex. 1-3, p. 514). In a study designed to quantify dose-response levels for irritation in human volunteers, subjects were exposed for 15 minutes to these products at aldehyde concentrations (measured as formaldehyde, which is the best indirect measure of rosin pyrolysis products) of 0.04 to 0.2 mg/m3 (U.S. Public Health Service 1965, as cited in ACGIH 1986/Ex. 1-3, p. 514). Subjects detected the odor at 0.07 mg/m 3, and 80 percent of subjects reported moderate to severe irritation of the eyes, nose, and throat at concentrations of 0.12 mg/m3 or above. At levels below 0.05 mg/m3, fewer than 10 percent of subjects experienced irritation. Mucous membrane irritation occurred in 30 percent of subjects exposed at
0.07 mg/m3 (U.S. Public Health Service 1965, as cited in ACGIH
1986/Ex. 1-3, p. 514).
"NIOSH (Ex. 8-47, Table N6B; Tr. p. 3-97 to 3-98) did not concur with OSHA's selection of a TWA limit of 0.1 mg/m3 and recommended a ceiling limit of 0.1 ppm for a 15-minute period. In addition, NIOSH (the only commenter to the rulemaking record) considers these thermal decomposition products to be likely candidates for a separate 6(b) rulemaking.
"OSHA is establishing an 8-hour TWA limit of 0.1 mg/m3, measured as formaldehyde, for rosin core solder pyrolysis products. OSHA concludes that this limit will protect employees from the significant risk of respiratory tract irritation, which is a material impairment of health, that exists at levels above the new PEL."
If, as has been claimed, Lead at soldering temperatures does not outgas lead compounds, (argument based on the vapor pressure of lead), then by the same logic a charcoal grill doesn't outgas carbon compounds either. After all, carbon has a very high vapor pressure and a very high melting point.
In real-life, carbon heated in the presense of air forms carbon dioxide and cabon monoxide, both of which are gases at room temperature. The high vapor pressure just means that you won't get pure carbon gas, not that you won't get carbon dioxide or carbon monoxide gas. The vapor pressure and melting point of an element tells you nothing about the vapor pressure and melting point of oxides, sulphates, etc. of that element.
It is also pretty silly to refer to the melting and boiling points of pure lead when you already know that you are dealing with a tin-lead alloy with a melting point lower than tin or lead.
Lead readily oxidises to lead monoxide. This causes the gray color you see. Scrape the lead with a knife and you will see that unoxidised lead is bright and shiny. This oxidisation is purely a surface effect; to get the lead to actually burn into lead monoxide in bulk takes over a thousand degrees F.
Tin-lead solder does not show the same grey lead monoxide surface, because it preferentially forms a *tin* oxide film. This forms as a byproduct a small amount of micron-sized lead monoxide dust (Litharge and Massicot forms) on the surface. That's why washing your hands after soldering is important.
Lead monoxide and water vapor form lead hydroxide and, with the carbonic acid in the water vapor, lead carbonate. I do not know to what exient the lead hydroxide and lead carbonate get into the smoke from the flux. I would geuss not much, but I have no data.
Please note that a "carcinogen" is NOT an agent which "causes" cancer!!! It is only an agent that makes cancer more likely. Hence smoking does NOT "cause" cancer. Smoking only makes it more likely that you may get it.
I know some are laughing, but truth is that mental attitude is a HUGE factor in curing cancer (and contracting it, I presume) There are so many cases of "spontaneous remission" that are clearly related to mental attitude (like the Placebo effect) that mental attitude clearly qualifies as both a "carcinogen" as well as a "cure" for cancer.
"Various psychologic methods are being promoted to cancer patients as cures or adjuncts to other treatment. The techniques include imagery, visualization, meditation, progressive muscle relaxation, and various forms of psychotherapy. These techniques may reduce stress, alleviate depression, help control pain, and enhance patients' feelings of mastery and control. Individual and group support can have a positive impact on quality of life and overall attitude. A positive attitude may increase a patient's chance of surviving cancer by increasing compliance with proven treatment. However, it has not been demonstrated that emotions directly influence the course of the disease.
"Bernie Siegel, M.D., author of Love, Medicine & Miracles and Peace, Love & Healing, claims that "happy people generally don't get sick" and that "one's attitude toward oneself is the single most important factor in healing or staying well." Siegel also states that "a vigorous immune system can overcome cancer if it is not interfered with, and emotional growth toward greater self-acceptance and fulfillment helps keep the immune system strong." However, he has published no scientific study supporting these claims. A 10-year study co-authored by Siegel found that 34 breast cancer patients participating in his program did not live longer after diagnosis than comparable nonparticipants. The program consisted of weekly peer support and family therapy, individual counseling, and the use of positive imagery [52]. In November 1998, Siegel sent a series of email messages to Dr. Barrett in which he said that the study bearing his name had been done by a student and was improperly designed.
"O. Carl Simonton, M.D., claims that cancers can be affected by relaxation and visualization techniques. He claims that this approach can lessen fears and tension, strengthen the patient's will to live, increase optimism, and alter the course of a malignancy by strengthening the immune system. However, he has not published the results of any well- designed study testing his ideas. Simonton theorizes that the brain can stimulate endocrine glands to inspire the immune system to attack cancer cells. He and his wife Stephanie (a psychotherapist) taught cancer patients to imagine their cancer being destroyed by their white blood cells. However, there is no evidence that white cells a ctually attack cancer cells in this manner or that "immune suppression" is a factor in the development of common cancers.
"Simonton's book Getting Well Again included reports on patients who got better after using his methods. However, an analysis of five of the reports that might seem most impressive to laypersons noted that two of the patients had undergone standard treatment, one had a slow-growing tumor, and one probably did not have cancer. The fifth patient's tumor was treatable by standard means.
"Some people suggest that Simonton's program may have positive effects by helping people to relax and to feel that they are "doing something" positive. Although his approach is physically harmless, it can waste people's time and money and encourage some to abandon effective care. It can also cause people to feel ashamed or guilty that some inner inadequacy caused them to develop cancer and is interfering with their recovery. Patients seeking a support program should select one that is based on scientific principles and has competent professional supervision."
REFERENCES:
Friedlander ER. Mental imagery. In Barrett S, Cassileth BR. Dubious cancer treatment. Tampa, Florida: American Cancer Society, Florida Division, 1991, pp 73-78.
Questionable Cancer Therapies, Stephen Barrett, M.D.. Victor Herbert, M.D., J.D.. _Quackwatch_
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