E-Mail Message

From: Lenny Solomon
To: DEAS/Physics Safety Committee
Date: December 1, 2003

Subject: Eye Wash Stations

Several weeks ago an accident occurred that required one of our post docs to use an eyewash station. Although this person has fully recovered, significant eye irritation was experienced that continued for several days after the eyewash was employed. This called into question the safety of our eyewash stations.

Before I go on, I will state the conclusion here, as well as at the end of this message. Our eyewash stations are safe and are to be used if an irritant chemical is accidentally splashed into the eye. Flush for 15 minutes and then go to UHS for an exam. Last but not least, ALWAYS WEAR GOGGLES WHEN USING CHEMICALS. This is the best way to ensure that you will not cause yourself any damage.

When this person’s eye irritation persisted even in the eye that had not been chemically exposed, lab members measured the pH of the water in the station and found it to be above 9. At that point, several members of the group asked whether such a high pH (neutral being 7.0) could cause damage to the eye. This topic has now been researched on several fronts. Below is a summary of the findings.

A few days following this accident, the pH level was measured with a calibrated meter under several different conditions. On 11/4/03, at 3:40 pm, on the 5th floor of McKay, the tap water had a pH of 8.72 while the eyewash water was measured to be 10.11. After flushing the eyewash station for 40 minutes eye wash water measured 9.99. As a comparison, measurements were subsequently made in the Whitesides area in Mallinckrodt. The tap water measured 5.95 and the eyewash water was 10.23.

After these measurements were taken, EH&S spoke to Edward Dowling, Laboratory Manager of Cambridge Water Department. We were told that Cambridge specifically maintains the pH of the water supply between 9.0-9.3, to reduce corrosiveness in order to minimize the levels of lead and copper. In other words, in theory, this should be the baseline we should see This obviously doesn’t explain the acidic reading of the tap water in the Whitesides area or the lower reading in the McKay tap water.

Sam Lipson, Director of Environmental Health for the City of Cambridge said that he has never been involved in a study of eye irritation from pH 9 water. He went on to say that Cambridge has had high pH water for a long time and that Cambridge residents are not shy about complaining. He has never had any complaints about eye irritation from the water.

EH&S also spoke with Dr. Matthew Gardiner. MD, Director of Emergency Ophthalmology Services at the Mass Eye and Ear Institute (MEEI). He stated that eyes are always irritated after eyewash use and he did not have any recommendations pertaining to pH level. He was more concerned with the buffering capacity of the water than the actual pH value. Usually any the irritation goes away overnight. After a chemical splash one wants volumes of water to get out the irritant. The most important thing to do after a splash is to flush material out of one’s eyes.

He went on to say that even water with a pH of 7 is very different from tears. Eyes need the electrolytes provided by tears. Water does not provide this. He noted that ideally one would irrigate with normal saline solution. The ultimate eyewash would be “BSS – Balanced Salt Solution.”

The ionic properties of water are not friendly to the eye – even at pH 7. In the operating room they use “artificial tears” mixture of Na Mg and bicarbonate ions attempting to match the ionic concentration of tears as closely as possible.

He concluded by saying that the eye is a robust organ able to survive most insults and that almost assuredly no permanent damage would occur from flushing with tap water.

In the ANSI Z358.1-1998 Emergency Eyewash and Shower Equipment standard, pH is not specified. The term “flushing fluid” for eyewashes is defined as “potable water, preserved water, preserved buffered saline solution or other medically acceptable solution manufactured and labeled in accordance with acceptable government regulations.” No government regulation is listed. “Potable water” is defined as “water that is suitable for drinking.”

The EPA Revised Guidance Manual for Selecting Lead and Copper Control Strategies (Office of Water EPA-816- R-03-001) states that to comply to Pb and Cu levels, EPA’s Dissolved Inorganic Carbonate Determination Table can be applied to (water) systems up to pH 10.4.

Dr. Joseph Harrington, professor of environmental health engineering in the Division, has served as the president of the Cambridge Water Board for the past 9 years. The only complaint he has heard of the pH being too high was related to difficulty meeting MWRA maximum discharge requirement He said the raised pH allows them to meet their lead and copper requirements.

I posed the pH question to Jean Manoli, of the Massachusetts Department of Occupational Safety. She stated that she had never seen any other specification other than “potable” to define the necessary water quality of an eyewash. She also said that it was her understanding that permanent eye damage cannot occur at a pH level lower than 11.

In an effort to explain the difference of pH level between the tap and eyewash water in Mckay, Ed Poirer from Harvard’s Facilities Maintenance Organization (FMO) was interviewed. He said that the McKay eyewash water is delivered from a water tank in the basement of the building that is approximately 3-4’ in diameter and 7’ tall (~500 gal.) The water in the tank comes from the potable water supply to the building and is heated to provide tempered water. The tank has been flushed semi-annually. (To be more conservative, in the future it will be flushed quarterly).

At a meeting I attended a couple of weeks ago specifically about eyewash stations, I learned several things. There are both OSHA regulations and ANSI standards that govern the design and maintenance of eyewash stations. Between them they specify what should be done for weekly, quarterly, semi-yearly, and yearly maintenance of such facilities. Below is a summary.

WEEKLY- The stations should be flushed for 3 to 5 minutes. I need the Safety Committee members to see that it’s done. A reminder will go out each week, probably with the SAA e-mail that is already sent. Please keep a log sheet near the eyewash that documents when it was done each week and by whom.

QUARTERLY- OSHA states that all stations must be inspected for flow rate (0.5 to 3.0 gallons/min), temperature (18 to 34 C), and operation. These inspections must be recorded and documented. In addition to this requirement , we will also inspect the eye cup filter heads, and clean or replace as necessary. As I said before, we will also drain and refill the storage tanks quarterly.

YEARLY- OSHA calls for a full engineering and operations test.

CONCLUSIONS Any extended irrigation to the eye will irritate the eye. This is to be expected. For most individuals this irritation should go away after 24 hours. However, it can obviously last longer in some cases. There also might be a connection between the length of time it takes to feel normal again and the use of contact lens. If you do have an accident, flush the eye out thoroughly by using the eyewash stations. While you might have some lingering eye irritation, it is the best first aid to try and prevent any permanent damage.

Last but not least, ALWAYS WEAR GOGGLES WHEN USING CHEMICALS. This is the best way to ensure that you will not cause yourself any damage.

Thank you.

Lenny